Rationing of adjustment work on CNC machines. Rationing of work performed on CNC machines. Time spent on setting up the machine

2.2 Rationing of work of the main personnel of the organization

Let's consider the rationing of the work of the main personnel using specific examples.
1. Organization, regulation and remuneration of machine tool work.
Multi-line service- this is a type of service in which one worker serves several machines. Multi-line service can be individual and team-based. The division of labor in multi-station brigades is either qualifying or functional; in some cases, the so-called pair service is used, when, for example, two workers of the same profession and qualifications serve several machines. Multi-station service is most beneficial if the non-overlapping machine time is longer than the time of manual operations, active observation and transitions. However, often multi-station service is economically feasible even if this balance of time is violated, in particular, when there is a shortage work force when there is free equipment.
To establish time norms for each element of a production operation, regardless of the form of labor organization, analytical and computational work is carried out separately. In this case, they are guided by the provision that the time norm for an operation must satisfy the following basic conditions:
1) the technological process provides for the rational and full use of technical means: equipment, fixtures, tools and mechanisms involved in the work;
2) The processing mode is established based on best practices;
3) provides for the full workload of the working day with productive work.
Consider the order of rationing of the main and auxiliary times.
The processing modes on the machine are selected by the technologist depending on the material, tool and equipment. The main time is determined by the formulas depending on the type of work (turning, milling) for each transition separately.
When working on metal-working machines, the cost rate of the main machine time can be determined by the formula (9):

to = li / n * S, (9)

where to is the normal time, min; l is the estimated length of processing, mm; i is the number of passes; n is the number of revolutions or double strokes available on the machine, per minute; S is the feed rate of the cutting tool per revolution or double stroke , mm.
The rationing of auxiliary time is carried out using standards that are established depending on the type of production: more differential - in mass production, the most enlarged - in single production. At the same time, complexes of labor auxiliary techniques are first determined. So, in mass production, the auxiliary time for the operation is normalized according to the following sets of techniques:
1) Time for installation and removal of the part. The time standards for the installation and removal of a part in the general machine-building standards for auxiliary time are given for typical methods of installation and fastening, taking into account their location when manually installed at a distance of 0.5-1 m from the machine.
2) The time associated with the transition consists of the time for approaching the tool to the workpiece or the workpiece surface, setting the tool to size, turning on the feed and rotating the spindle to take a test chip, measuring when taking a test chip, turning on the spindle rotation and feeding, retracting the tool, etc. etc.
3) Time associated with mode change machine operation and changing the tool, consists of the time of receptions for changing the frequency of rotation of the spindle or table strokes, the amount of feed, changing the tool, moving parts of the machine and accessories.
4) The time for control operations includes the time spent on control measurements, which are made after the end of surface treatment.
The peculiarities of the wages of a multi-machine worker are determined, first of all, by the need to take into account the degree of his employment during the work shift and to establish the appropriate additional payments to tariff rates. They are established depending on the ratio between the normative and project employment of the worker. The maximum level of surcharges, as a rule, should not exceed 30% of the tariff rate. This level corresponds to the equality of the project and normative levels of employment, that is, the additional payments increase as the project employment increases, but only as long as the worker has time to rest during the shift.
2. Organization, regulation of stamping and foundry works.
When standardizing forging and stamping works, which include hot stamping under hammers and presses, upsetting on horizontal forging machines and free forging, the following features of this type of metal processing should be taken into account:
1) The presence of two parallel processes - heating of workpieces, metal deformation and the need for separate determination of the time for heating of workpieces, stamping (forging) and trimming of parts.
2) The brigade nature of the work and the need to ensure an even load of each member of the brigade.
3) An insignificant specific gravity of the metal deformation time in the standard of piece time.
4) The need to determine the auxiliary time for individual operations and techniques.
5) The need to apply a differentiated rate setting method for calculating manual and machine time.
6) Establishing the time norm for forging and stamping work at the greatest operational time of all members of the team, since when the process of heating the blanks with the metal deformation process is carried out in parallel, the work is organized in such a way that the heating time of the blanks overlaps with the forging time and partly with the maintenance time of the workplace, therefore, the heating time is usually not included in the standards.
The unit time rate for forging on hammers and presses, depending on the scale of production of blanks, is calculated by the formula (10):

tsht = (∑ (to * Ky + tv) * (1 + (αobs + αdetl) / 100) * Km + tnshtv) * Кn, (10)

where to is the main time of one hammer blow; Ky is the number of blows required for deformation of the metal; Km is the correction factor for forging of various grades of steel; tnstv is the auxiliary time for free forging associated with the product; Кn is a correction factor that takes into account the change in the rate of work depending on the batch size.
The values ​​of the correction factor are given in table 28.

Table 28

Values ​​of the correction factor Kn

In the "General machine-building standards for forging on hammers and presses" auxiliary time is given taking into account the time of rest breaks and personal needs and the time of breaks associated with the organization of the technological process.
3. Organization, rationing of fitter-assembly and welding works.
Locksmith work on the processing of blanks is a cold metal cutting, performed by hand or power tools. Such processing aims to give the parts the required shape, dimensions and surface roughness by cutting with a hacksaw, chopping off, filing, scraping, drilling, threading and chamfering, burrs
etc.
The technological features of the listed processes are characterized by the tools and equipment used for this work. In assembly work, operations can be performed directly at assembly sites without placing the product in a vice or on a workbench.
The standardization of fitting and assembly work is carried out in the following sequence:
1) establishment of the object, purpose and method of rationing;
2) analysis of the actual operations of locksmithing and assembly, identification of the compliance of the organization of labor in the workplace with the requirements of the ITU, the choice of a rational option for its technological content, which ensures the least expenditure of working time while observing the technical requirements for processing;
3) the choice of standards for rationing in accordance with the type of production, the nature of the work;
4) designing the content of work according to work methods and identifying the compliance of the actual working conditions with the normative ones;
5) calculation of operational time for an operation based on the determination of the duration of individual elements of work according to normative materials. The operational time is determined by the formula (11):

Top = ∑topi * k, (11)

where topi is the operational time of the i-th computational complex of works, min; k is the total correction factor for changing the working conditions when the i-th computational complex is performed.
In the conditions of small-scale and one-off production, operational time is not allocated when standardizing fitter and assembly work, and the calculation is carried out in aggregate by piece time for each i-th computational complex.
6) Calculation of time for servicing the workplace, rest and personal needs.
Locksmith and assembly work is mostly manual, so it is difficult to allocate auxiliary time. There are two types of tables in the collections of standards for plumbing and assembly work (when standardizing by operational time).
In the first type of tables, the main and auxiliary time is included in the standard time, in addition to the preparatory and final time, time for servicing the workplace and time for rest and personal needs. The time rate is set per unit of measurement.
In the second kind of tables, the operational time is given with the inclusion of auxiliary times related only to the tool or workpiece material, but not including the time associated with the entire part or assembly.
As for the rationing of welding, we can say that electric welding, gas, contact and electron beam welding are used in mechanical engineering.
Here, the main time is the time during which the formation takes place weld by melting the base and filler material (electrode, electrode or filler wire).
The main time for welding 1 m of a seam is determined by the formula (12):

to1I = (60 * F * Þ) / (J * αн), (12)

where F is the cross-sectional area of ​​the seam, mm2; Þ - specific gravity of the deposited metal, g / cm3; J - welding current, a; αн - deposition coefficient, g / a * h.
The most common elements of auxiliary time, depending on the product and the type of equipment for all types of arc welding, include the time for installation, rotation, removal of the product, fastening and unfastening of parts, and movement of the welder. For all types of arc welding, it is set according to the standards.
In automatic and semi-automatic (cassette) welding, the time required for refueling one cassette is separately allocated. The list of costs is shown in table 29.

Table 29

Time for one refueling of the cassette

4. Features of the regulation of automated production operations.
Automated manufacturing process shows that when organizing labor, its forms are influenced by the presence automatic systems and devices.
The main way to automate the processes of mechanical processing of parts of small-scale and one-off production is the use of machine tools with numerical control (CNC). CNC machines are semi-automatic machines or automatic machines, all movable parts of which perform working and auxiliary movements automatically according to a predetermined program. The structure of such a program includes technological commands and numerical values ​​of the displacements of the working bodies of the machine. Changeover of a CNC machine, including a program change, requires little time, therefore these machines are most suitable for automating small-scale production.
A feature of the standardization of the operations of mechanical processing of parts on CNC machines is that the main time (machine) and the time associated with the transition make up a single value Ta - the time of automatic operation of the machine according to the program compiled by the technologist-programmer, which consists of the main time of the automatic operation of the Toa machine and the auxiliary time of the machine according to the program Tva, that is (13), (14), (15):

Ta = Toa + Tva, (13)

Toa = ∑ (Li / smi), (14)

Tva = Tvha + Toast, (15)
where Li is the length of the path traversed by the tool or part in the direction of feed when processing the i-th technological section (taking into account the penetration and overrun); smin-minute feed in this area; i = 1, 2, ..., n- the number of technological processing areas; Tvha - time for the execution of automatic auxiliary moves (supply of the part or tools from the starting points to the processing zones and retraction, setting the tool to size, changing the numerical value and direction of feed); Toast is the time of technological pauses-stops of feeding and rotation of the spindle to check the dimensions, inspect or change the tool.
Flexible automated system(GPS) is a system of machines and mechanisms designed for processing various structurally and technologically similar parts in small batches, one by one, without direct human participation. The constituent parts GPS are subsystems: technological, transport, storage, instrumental service and computer-aided control.
The central element of GPS is flexible technological system(GTS), which is a set of multi-operation CNC machines (such as a machining center) that directly process items.
Depending on the number of machines in the FMS there are: flexible production module (FMP); flexible production line(GPL); flexible production area (GPU); flexible production of a workshop (GPP) and a plant (GPP).
A flexible production module is a technological piece of equipment (CNC machine) equipped with manipulators or robots for loading and unloading parts and a tool magazine. The main feature of the PMG is the ability to work without human participation and the ability to integrate into a higher-ranked system. The flexible line consists of several modules equipped with transport and instrumental systems and controlled by a microcomputer. Flexible section - a type of GPL; it differs in the composition and interchangeability of technological equipment and mode of transport.
Transport and accumulation subsystem is a set of automated warehouses for workpieces and parts, accumulators at machine tools with automatic loading and unloading and automatic Vehicle, serving to move the processed items from the warehouse to the machines and vice versa (robotic trolleys, conveyors, roller tables, etc.).
The subsystem of instrumental service includes warehouses of tools and devices, a department for preparing tools for work (sharpening, assembling, assembling stores, etc.) and a flexible automated system for installing, removing and moving tools from warehouses and vice versa.
Subsystem automated control is a complex of technological means with computers capable of receiving information from automated systems enterprises: ACS ( scheduling schedules), CAD (drawing of a part), ASTPP (technological process of processing and control of a part), transform it using control programs, transmit commands directly executive bodies equipment of all GPS subsystems.
Thus, there are two streams of resources functioning in the GPS: material and informational. The material flow ensures the implementation of all the main and auxiliary operations of the processing of objects: supply of blanks, tools and their installation on machines; mechanical processing of parts; removing finished parts and moving them to the warehouse; tool change and movement; control of processing and tool condition; cleaning of shavings and supply of cutting fluid. The information flow provides: the sequence, timing and number of processed items, provided for by the work plans of the State Fire Service; transfer of processing programs directly to the executive bodies of machine tools, work programs of robots, installation and transfer mechanisms, programs for providing blanks, tools, auxiliary materials, control programs for the entire complex and accounting for its work, as well as group control of machines, transport storage mechanisms, system of instrumental service.
The main features of flexible manufacturing systems are as follows:
1) Employees of the State Border Service are not directly involved in the impact on the subject of labor. Their main task is to ensure the efficient operation of the equipment. With the change in the functions of workers, the structure of the costs of their working time changes. Its main part is spent on adjustment, preventive maintenance and equipment repair.
2) The number of units of FPS technological equipment exceeds the number of employees in each group: adjusters, mechanics, repairmen, electronics engineers, etc. Therefore, it is necessary to establish optimal relationships between the number of units of equipment and the number of employees in each group, to normalize the time spent in two sections : in relation to equipment and workers.
3) To increase the level of reliability of the functioning of the GPS, it is necessary to create complex end-to-end brigades with labor remuneration for the final product. It should be borne in mind that the downtime of equipment during and while waiting for service is the less, the wider the profile of each employee in relation to the functions performed and the service areas of the equipment.
The theory and experience of operating the operating FPS show that at present the norms of the duration of operations in relation to equipment (norms of machine-tool intensity of operations), norms of labor intensity, norms of number and maintenance are of the greatest practical importance.
For practical calculations of duration norms, it is necessary to proceed from the division of the normalized time consumption into direct and indirect ones. The former can be fairly accurately calculated directly for a unit of production of a given type. The latter refer to all products manufactured at a given workplace or site, and therefore are included in the normalized duration of the operation in proportion to the value of direct costs.
The procedure for calculating labor standards in the State Border Service is as follows:
1) the coefficient of equipment utilization by the time of automatic operation is found, which is necessary to perform production program;
2) the standards for the employment rate of employees of each group are determined;
3) based on the relevant standards, a preliminary version of the labor intensity of each type of work and the number of norms for each group of workers is calculated;
4) the coefficients of the workload of employees of each group are determined, corresponding to the adopted version of the number of norms;
5) the coefficient of the time of automatic work corresponding to the adopted variant of the norms of the number is set;
6) the load factors of employees of each group and the time of automatic work are compared with their specified values;
7) the amount of costs for employees of all groups is determined;
8) for the variant of the norms of the number, recognized as optimal, the values ​​of the norms of the duration of the performance of technological operations for each detail are found;
9) based on the norms of the number and duration, the norms of labor intensity (time) are established for each detail, each group of workers and for the brigade as a whole.
In conditions automated production, including flexible production systems, to direct, as a rule, refer only to the time spent in the automatic operation of equipment. It is advisable to include indirect costs of time in the composition of the norm for the duration of operations, based on the following formula (16):

Нд = tа * (Тпл / (Тпл - Тнп)), (16)

where t is the operating time of the machine in automatic mode during the manufacture of a unit of production for a given operation; Tpl is the planned daily fund of operating time of the GPS; Tnp is the duration of normalized interruptions in the operation of technological equipment associated with maintenance and waiting for service by workers of all groups during Tpl.
The value of Тнп should include only those real interruptions in the operation of the equipment, which are objectively inevitable in the conditions of a particular GPS, based on the optimal maintenance schedule for the equipment, the established work schedule and rest of workers. The composition of the consumer goods is determined by the design features of the analyzed system and the operating conditions. As a rule, the value of Тнп includes the duration of commissioning, adjustment, testing works, which cannot be covered by machine time, the time of equipment downtime associated with the regulated maintenance of mechanical, electrical, electronic and other subsystems, the time of manufacture and control of test parts, etc. When establishing the composition of the Type, one should strive to overlap some work with others as much as possible, to perform them in parallel, to combine the functions of employees of the State Border Service, to use the advantages of the brigade organization of labor, collective contracting.
In all GPS equipment, the equipment is not turned off during the rest of the workers, which should be installed on a sliding schedule. Therefore, time for rest and personal needs is not included in the consumer goods. It is taken into account when calculating the optimal standards of service and the number, which are set at a level that makes it possible to realize the standard time for rest due to mutual substitutions of workers.
The second factor can be expressed in terms of the equipment utilization rate in terms of the time of automatic operation (17):

Tm / (Tm - Tnp) = Tm / Ta = 1 / Ka, (17)

where Ta is the time of automatic operation of the equipment for the planned period of its operation Tpl.
The average normalized production time (duration rate) is determined by the formula (18):

Нд = tа / Cap, (18)

where Cap is the planned utilization factor of the equipment by the time of automatic operation.
Formula (18) is most convenient for practical standardization of the duration of operations, since it includes two parameters used in all basic technological and organizational planning calculations of the FMS.
For practical calculations, the following formula for the complexity of operations is convenient (19):

Нт = (Нч / N * C * Ki) * Нд, (19)

where N is the total number of GPS modules; C is the number of shifts of equipment operation; Ki is the planned utilization factor of equipment.
When calculating the total employment of SBS workers, it is advisable to separately take into account their employment with the main functions - performing production work and additional - performing supporting work (20):

Ks (X) = Kp (X) + Ko (X), (20)

where Kp (X) and Co (X) is the employment rate of workers in this group by performing the corresponding production and supporting work.
The optimal headcount of the FPS is established on the basis of the relations (21), (22):

Кз (Х) ≤ Кзн, ​​(21)

Ka (X) ≥ Kahn, (22)

Coefficient Ka (X) is determined for each variant of the norms of the number of employees according to the formula (23):

Ka (Nch) = Tpl - Tnp (Nch), (23)

where Тнп (Нч) is the duration of standardized interruptions in the operation of the equipment, depending on the adopted option for the number of employees, the form of division and cooperation of labor, equipment maintenance regulations, and the mode of work and rest.

In the conditions of automatic lines (including rotary and rotary-conveyor lines) for labor rationing, the following are used: norms for the number of personnel; norms for the duration of production operations; time norms (labor intensity of operations) for individual groups workers and in general for the brigade serving the line; production rates; standardized tasks.
The main role is played by the norms of the number of personnel (adjusters, mechanics, repairmen, electricians, electronics technicians) who service the line in accordance with the established regulations and ensure the implementation of the production program.
The basis for calculating the rate of time and production in the conditions of automatic lines is the technical (passport) productivity of the line rm, which determines the number of units of production that can be obtained from this equipment per hour or in another unit of time when operating in automatic mode.
The production rate is set based on the technical performance of the unit and the utilization rate of the line according to the time of automatic operation (24):

Нв = rm * Can, (24)
After determining the production rate, the labor intensity (time) rate for i-th group(professions) workers (25):

Нтi = Тпл * (Нчi / Нв), (25)

On the basis of the norm of the number, time and production, a standardized task is established. It indicates the scope of work for the regulated maintenance of the line in the planned period, the time for performing these works, the standard number of workers, the planned volume of line production.
If on an automatic line, products of several names are manufactured, then the calculations of the norms of time and production can be carried out for sets of products. Along with this, for multidisciplinary lines, it may be more expedient to calculate the norms of duration Нд and labor intensity Нт according to the method for GPS. In this case, calculations are performed according to formulas (26), (27):

Ndk = tak / Kan, (26)

Нтk = Нч * (Ндк / But), (27)

where tak is the time of automatic operation of the equipment in the manufacture of parts of the k-th type.

METHODOLOGICAL DEVELOPMENT FOR THE DISCIPLINE

"TECHNOLOGY OF ENGINEERING"

Compiled by teacher: Fazlova Z.M.

Introduction

The intensification of production, the successful introduction of the latest technology and technology requires improving the organization of labor, production and management, which is possible only on the basis of technical regulation.

Labor rationing is the establishment of a measure of labor costs, mf of the total socially necessary expenditures of working time for the production of products of a certain consumer value for a given period of production and technical conditions. The most important tasks of labor rationing are the consistent improvement of the organization of labor and production, a decrease in the labor intensity of products, the maintenance of economically sound relationships between the growth of labor productivity and wages... Labor rationing should contribute to the active introduction of advanced experience, achievements of science and technology.

The methodological development "Rationing of work performed on machines with PE U" allows you to acquire the necessary skills to establish a reasonable rate of time for performing a technological operation. It outlines the theoretical foundations for establishing the norms of time for a technological operation with CNC. The appendix contains the basic engineering labor standards.

REGULATION OF WORKS, PERFORMED ON CNC MACHINES

The main way to automate the processes of mechanical processing of parts of small-scale and one-off production is the use of machine tools with numerical control (CNC). CNC machines are semi-automatic or automatic machines, all moving parts of which are made and working and auxiliary movements automatically according to a predetermined program. It includes technological commands and numerical values ​​of the displacements of the working bodies of the machine.

Changeover of a CNC machine, including a program change, requires little time, so these machines are most suitable for automating small-scale production.

Time to complete operations on CNC machines, N bp consists of the preparatory-final time T pz and the unit time T pcs:

(1)

T pc = (T c.a + T in K TV)
(2)

where n - the number of parts in the manufactured batch;

Т Ц.а - cycle time of automatic operation of the machine according to the program, min;

T in - auxiliary time, min;

K TV - a correction factor for the time of performing manual auxiliary work, depending on the batch of processed parts;

and those, and org, and ex - time for technological and organizational maintenance of the workplace, for rest and personal needs with one-way service,% of the operational time.

The cycle time of automatic operation of the machine according to the program is calculated by the formula

T c.a = T about + T mv (3)

where T about is the main (technological) time for processing one part, min:

T about = (4)

L i is the length of the path traversed by the tool or part in the direction of feed during processing of the technological section (taking into account the penetration and overrun);

s m - minute feed at a given technological section, mm / min;

T mv - machine-auxiliary time according to the program (for the approach and withdrawal of a part or tool from the starting points into the processing zones, setting the tool to size, changing the tool, changing the value and direction of feed, the time of technological pauses (stops), etc.) , min.

Auxiliary time is defined as follows:

T in = T in.y + T in.op + T in.meas (5)

where T v.y - time for installation and removal of the part, min;

T v.op - auxiliary time associated with the operation (not included in the control program), min;

T in. rev - auxiliary non-overlapping time for measurement, min.

Time standards for installation and removal of a part are determined by the types of fixtures depending on the types of machines and provide for the most common methods of installation, alignment and fastening of parts in universal and special clamps and fixtures.

The auxiliary time associated with the operation subdivided into:

a) for the auxiliary time associated with the operation, not included during the cycle of automatic operation of the machine according to the program;

b) the machine-auxiliary time associated with the transition included in the program related to the automatic auxiliary operation of the machine.

The required dimensions of parts processed on CNC machines are provided by the design of the machine or cutting tool and the accuracy of their adjustment. Concerning time for control measurements should be included in the unit time rate only if it is provided for by the technological process, and it cannot be overridden by the cycle time of the automatic operation of the machine according to the program.

Time to service the workplace is determined according to the standards and standard sizes of equipment, taking into account single-station and multi-station service as a percentage of operating time.

Time for rest and personal needs when servicing one worker, one machine is not separately allocated and taken into account in time for servicing the workplace.

Preparatory and final time standards are designed for setting up CNC machines for processing parts according to embedded control programs and do not include additional programming actions directly at the workplace (except for machines equipped with operational software control systems).

Rates of piece time for dimensional adjustment of the cutting tool outside the machine are intended for the standardization of work on adjusting the cutting tool for CNC machines, which is performed by toolmakers outside the machine in a specially equipped room with the help of special devices.

TYPICAL PROBLEM WITH SOLUTION

Initial data: part - shaft (Fig. 1); material - steel 30G; precision surface treatment 1,2,3 - IT10; roughness of surface treatment 1, 2 Ra5; 3 - Ra10.

Blank: production method - stamping (normal precision IT sixteen); surface condition - crusty; weight 4.5 kg; surface treatment allowance: 1 - 6 mm; 2 - 4 mm; 3 - 5 mm.

Machine: model 16K20FZ. Passport data:

spindle speed P(rpm): 10; eighteen; 25; 35.5; 50; 71; one hundred; 140; 180; 200; 250; 280; 355; 500; 560; 630; 710; 800; 1000; 1400; 2000;

feed range s m (mm / min)

along the coordinate axis X- 0,05...2800;

along the coordinate axis z - 0,1...5600;

the greatest force allowed by the longitudinal feed mechanism - 8000 N, by the transverse feed mechanism - 3600 N;

main drive power - 11 kW;

the range of regulation of the frequency of rotation of the electric motor of constant power - 1500 ... 4500 rpm.

Operation: basing in the centers, with the installation of the leash on the surface.

1. Selection of processing stages.

The necessary processing stages are determined. To obtain the dimensions of the part corresponding to the quality of 10, from the workpiece of the quality 16, it is necessary to carry out processing in three stages: roughing, semi-finishing and finishing.

2. Choice of cutting depth.

Determine the minimum required depth of cut for the semi-finishing and finishing stages of processing (Appendix 5).

In the finishing stage for the surface 1, the diameter of which corresponds to the size interval 8 ... 30 mm, the depth of cut is recommended t = 0.6 mm; for surface 2, the diameter of which corresponds to the size interval 30 ... 50 mm, t= 0.7 mm; for surface 3, the diameter of which corresponds to the size interval 50 ... 80 mm, t = 0.8 mm.

Likewise, at semi-finishing stage for the surface / it is recommended t = 1.0 mm; for surface 2 - t - 1.3 mm; for surface 3 - t = 1.5 mm.

Figure 1 - Sketch of the shaft and the trajectory of the movement of tools

The depth of cut for the roughing stage of machining is determined based on the total machining allowance and the sum of the depths of cut for the finishing and semi-finishing stages: for surface 1 - t = 4.4 mm; for surface 2 - t = 2.0 mm; for surface 3 - t = 2.7 mm. The selected values ​​are entered in table 1.

Table 1 - Determination of cutting conditions

3. Tool selection.

On the 16K20FZ machine, cutters with a holder section of 25 x 25 mm, a plate thickness of 6.4 mm, are used.

Based on the processing conditions, a triangular shape of an insert with a corner at the top is adopted
° of hard alloy T15K6 for roughing and semi-finishing stages of processing and T30K4 - for finishing stage (Appendix 3).

Standard durability period: T = 30 minutes.

4. Choice of feed.

4.1. For the roughing stage of processing, the feed is selected according to the adj. 3.

For surface 1 when turning parts with a diameter of up to 50 mm and a depth of cut t = 4.4 mm feed s from = 0.35 mm / rev is recommended. For surfaces 2 and 3, respectively, it is recommended to feed s from = 0.45 mm / rev. and s from = 0.73 mm / rev.

By adj. 3 determine the correction factors for the feed depending on the tool material TO s and = 1.1 and the way of fixing the plate K sp = 1,0.

4.2. For the semi-finishing stage of processing, the feed values ​​are determined according to App. 3 in the same way: for surfaces 1 and 2 s from = 0.27 mm / rev., Surfaces 3 s from = 0.49 mm / rev.

Correction factors for the feed depending on the tool material K s and = 1.1, the method of fixing the platinum K sp = 1.0.

By adj. 3 we determine the correction factors for the supply of rough and semi-finishing stages of machining for changed processing conditions: depending on the section of the tool holder TO s d = 1.0; cutting strength K s l = 1.05; mechanical properties of the processed material TO s and = 1.0; workpiece installation diagrams TO at = 0.90; workpiece surface conditions K s n = 0.85; geometric parameters of the cutter K sp = 0.95; rigidity of the machine K sj = 1,0.

The final feed of the roughing stage is determined by:

For surface 1

s pr1 = 0.35 1.1 1.0 1.0 1.05 1.0 0.9 0.85 0.95 1.0 = 0.29 mm / rev. ;

For surface 2

s pr2 = 0.45 1.1 1.0 1.0 1.05 1.0 0.9 0.85 0.95 1.0 = 0.38 mm / rev. ;

For surface 3

s pr3 = 0.73 1.1 1.0 1.0 1.05 1.0 0.9 0.85 0.95 1.0 = 0.61 mm / rev.

The feed of the semi-finishing stage of processing is calculated similarly:

for surfaces 1 and 2 s pr1,2 = 0.23 mm / rev .;

for a surface 3 s pr3 = 0.41 mm / rev.

for surface 1 s from1 = 0.14 mm / rev.,

for surface 2 s from2 = 0.12 mm / rev.,

for a surface of 3 s from 3 = 0.22 mm / rev.

By adj. 3, correction factors are determined for the feed of the finishing stage of processing for changed conditions: depending on the mechanical properties of the material being processed TO s = 1.0; workpiece installation diagrams TO at= 0.9; cutter radius K st = 1.0; quality of workpiece accuracy l 4 = 1.0. The final feed of the finishing stage is determined by:

for surface 1 s pr = 0.14 · 1.0 · 0.9 · 1.0 · 1.0 = 0.13 mm / rev.,

for surface 2 s p p = 0.12 · 1.0 · 0.9 · 1.0 · 1.0 = 0.11 mm / rev.,

For surface 3 s p p = 0.22 1.0 0.9 1.0 1.0 = 0.20 mm / rev

The calculated values ​​of the feeds of the finishing stage of surface treatment are entered in table. one.

5. Choice of cutting speed.

When roughing alloy steel with a crust with a depth of cut t = 4.4 mm and feed s pr = 0.29 mm / rev. cutting speed for the surface 1 V t = 149 m / min; with depth of cut t = 2.0 mm and feed s p p = 0.38 mm / rev. cutting speed for surface 2 V t = 159 m / min; with depth of cut t = 2.7 mm and feed s pr = 0.61 mm / rev. cutting speed for a surface of 3 V t = 136 m / min.

By adj. 8, 9, correction factors for the roughing stage of machining are selected depending on the tool material: for the surface 1 TO in = 1.0, for surfaces 2 and 3 TO in =0,95.

The final cutting speed for the roughing stage will be:

for surface 1 V 1 = 149 0.85 = 127 m / min;

for surface 2 V 2 = 159 0.81 = 129 m / min;

for surface 3 V 3 = 136 0.98 = 133 m / min.

5.2. At the semi-finishing stage of machining, alloy steel without a crust with a depth of cut t up to 3.0 mm and feed s p p = 0.23 mm / rev. cutting speed for surfaces 1 and 2 - V T = 228m / min; with depth of cut t = 1.5 mm and feed s pr = 0.41 mm / rev. cutting speed for surface 3 - V t = 185 m / min.

Correction factor for the semi-finishing stage depending on the tool material K v = 0,95.

By adj. 8, 9, the rest of the correction factors for the cutting speed are selected for roughing and semi-finishing stages of processing for the changed conditions:

depending on the machinability group of the material TO v With = 0,9;

type of processing K vo = 1,0;

rigidity of the machine K vo = 1,0;

mechanical properties of the processed material TO v m = 1.0; geometric parameters of the cutter:

for surfaces 1 and 2 C v f = 0.95, for the surface 3 C v f = 1.15; period of life of the cutting part TO v T = 1,0;

availability of cooling TO v f = 1,0.

Finally, the cutting speed at the roughing stage is determined by:

for surface 1 and 2 V 1,2 = 228 0.81 = 185 m / min;

for surface 3 V 3 = 185 0.98 = 181 m / min.

5.3. The cutting speed for the finishing stage of processing is determined by the app. 8, 9:

at t = 0.6 mm and s p p = 0.13 mm / rev. for surface 1 V T = 380 m / min;

at t = 0.7mm and s p p = 0.11 mm / rev. for surface 2 V T = 327 m / min;

at t = 0.8 mm and s p p = 0.2 mm / rev. V T = 300 m / min.

By adj. 8, 9, the correction factor for the cutting speed for the finishing stage is determined, depending on the tool material; K V n = 0.8. The correction factors for the finishing stage are numerically the same as those for the roughing and semi-finishing stages.

General correction factor for cutting speed at finishing stage: K v = 0.68 - for surfaces 1 and 2; K v = 0.80 - for the surface 3.

The final cutting speed in the finishing stage is:

for surface 1 V 1 = 380 0.68 = 258 m / min;

for surface 2 V 2 = 327 0.68 = 222 m / min;

for surface 3 V 3 = 300 0.80 = 240 m / min.

Tabular and corrected values ​​of cutting speed are entered in table. one.

5.4. Spindle speed according to the formula

During the roughing stage of surface treatment 1

n = = 1263 rpm

The rotational speed available on the machine is taken n f = = 1000 rpm. Then the actual cutting speed is determined by the formula:

V f = = 97.4 m / min.

The calculation of the spindle speed, its correction according to the machine passport and the calculation of the actual cutting speed for the remaining surfaces and processing stages are carried out in the same way. The calculation results are summarized in table. one.

Since the 16K20FZ machine is equipped with an automatic gearbox, the accepted values ​​of the spindle speeds are set directly in the control program. If the machine in use has manual switching of the spindle speed, the control program must provide technological stops for switching or set the lowest of the calculated speed for all surfaces and machining stages.

5.5. After calculating the actual cutting speed for the finishing stage, the feed is adjusted according to the roughness of the machined surface.

By adj. 8, 9 to obtain a roughness no more Ra5 when processing structural steel with a cutting speed V f = 100 m / min with a cutter with a nose radius r in = 1.0 mm, it is recommended to feed s from = 0.47 mm / rev.

By adj. 8, 9 determine the correction factors for the feed, the roughness of the processed surface for the changed conditions: depending on:

mechanical properties of the processed material K s = 1.0;

instrumental material K s and = 1.0;

type of processing K s about = 1.0;

the presence of cooling K s w = 1.0.

Finally, the maximum allowable roughness feed for the finishing stage of surface treatment 1 and 2 is determined by the formula

s about = 0.47 * 1.0 * 1.0 * 1.0 * 1.0 = 0.47 mm / rev.

The feed rates for the finishing stage 1 and 2, calculated above, do not exceed this value.

None of the calculated values ​​exceed the drive power of the main drive of the machine. Consequently, the established cutting mode for power is feasible (calculation is not given).

6. Definition of minute feed.

Minute feed according to the formula

s m = n f s about

In the roughing stage for surface 1

s m = 1000 0.28 = 280 mm / min.

The values ​​of the minute feed for the remaining surfaces and processing stages are calculated in the same way and are applied in table. one.

7. Determination of the time of automatic operation of the machine to the program.

The time of automatic operation of the machine according to the program for the general part.

For the I6VT2OFZ machine, the fixing time of the turret is T if = 2 s and the time of turning the turret by one position is T un = 1.

The calculation results are shown in table. 2.

8. Determination of the rate of piece time.

8.1. The piece time rate is determined by the formula (2)

8.2. The auxiliary time consists of the components, the choice of which is carried out according to the 1st part of the standards (formula (5)). Auxiliary time for the installation and removal of the part T v.y = 0.37 min (Appendix 12).

The auxiliary time associated with the operation, T v.op, contains the time for turning the machine on and off, for checking the return of the tool to a given point after processing, for installing and removing a shield that protects against splashing with an emulsion (App. 12, 13):

T v.op = 0.15 + 0.03 = 0.15 min.

Auxiliary time and control measurements contains the time for two measurements with a one-sided limit bracket, four measurements with a caliper and one measurement with a simple shaped template (Appendix 18):

T in. from = (0.045 + 0.05) + (0.11 + 0.13 + 0.18 + 0.21) + 0.13 = 0.855 min.

8.3. The time of automatic operation of the machine according to the program is calculated at each section of the tool path and is summarized in table. 2.

Table 2 - Time of automatic operation of the machine according to the program

Continuation of table 2

8.4. The final cycle time of automatic machine operation according to the program

T c.a = 2.743 + 0.645 = 3.39 min.

8.5. Accumulated auxiliary time

B = 0.37 + 0.18 + 0.855 = 1.405 min.

8.6. Time for organizational and technical maintenance of the workplace, rest and personal needs is 8% of the operational time (Appendix 16).

8.7. Finally the piece time rate:

T PC = (3.39+ 1.405) (1 + 0.08) = 5.18 min.

9. Preparatory and final time.

The preparatory and final time is determined by the formula

T pz = T pz1 + T pz2 + T pz3 + T p.obr.

Time for organizational preparation: T pz1 = 13 min,

time for setting up the machine, fixtures, numerical control devices

T pz2 = 4.0 + 1.2 + 0.4 + 0.8 + 0.8 + 1.0 + 1.2 + 1.2 + 2.5 + 0.3 = 13.4 min;

time for trial processing of a part

T pr. Sample = 2.2 + 0.945 = 3.145 min.

General preparatory and final time

T pz = 13 + 13.4 + 3.145 = 29.545 min.

10. Lot size of parts

n= N / S,

where S is the number of launches per year.

For medium batch production S = 12, therefore

n = 5000/12=417.

11. Piece-calculation time

T pcs to = T PC + T pz / n= 5.18 + 29.545 / 417 = 5.25min.

The main way to automate the processes of mechanical processing of parts of small-scale and one-off production is the use of machine tools with numerical control (CNC). CNC machines are semi-automatic or automatic machines, all moving parts of which perform working and auxiliary movements automatically according to a predetermined program. The structure of such a program includes technological commands and numerical values ​​of the displacements of the working bodies of the machine. Changeover of a CNC machine, including a program change, requires little time, so these machines are most suitable for automating small-scale production.

A feature of the standardization of the operations of machining parts on CNC machines is that the main time (machine) and the time associated with the transition make up a single value T a - the time of automatic operation of the machine according to the program compiled by the technologist-programmer, which consists of the main time automatic operation of the machine T o.a and auxiliary operating time of the machine according to the program T in., i.e.,

T a = T o.a + T in.a;

T v.a = T v.kh.a + T oc t

where Li is the length of the path traversed by the tool or part in the direction of feed when processing the 1st technological section (taking into account the penetration and overrun); s m - minute feed in this area; i == 1, 2, ..., n is the number of processing sections; Т в.х.а - time for the execution of automatic auxiliary moves (approach of the part or tools from the starting points to the processing zones and retraction, setting the tool to the size, changing the numerical value and direction of the feed); T rest - the time of technological pauses - stops of feeding and rotation of the spindle to check the dimensions, inspect or change the tool.

Subsidiary time self made T in not overlapped by the time of automatic operation of the machine,

T in = t mouth + t in.op + t counter,

where t mouth - auxiliary time for the installation and removal of the part; t c.op - auxiliary time associated with the operation; t counter - non-overlapping auxiliary time for control measurements of the part ..

Auxiliary time for installation and removal of parts weighing up to 3 kg on lathes and drilling machines in a self-centering chuck or mandrel. is determined by the formula

t mouth = aQ x

to determine auxiliary time for installation and removal of parts in centers or on a center mandrel lathe

t mouth = aQ x

to determine the auxiliary time for the installation and removal of parts in a self-centering or collet chuck on lathes and drilling machines

t set = aD in x l y in s l

to determine the auxiliary time for the installation and removal of parts on the table or square of the drilling and milling machine

t mouth = aQ x N y det + 0.4 (n b -2)

Coefficients and exponents for determining the auxiliary time for the installation and removal of parts in the vice of a drilling and milling machine

t mouth = aQ x

Auxiliary time machine control. (turning, drilling and milling machines)

t c.op = a + bSX o, Y o, Z o + cK + dl pl + aT a

Auxiliary time for control intentions.

t counter = SkD z meas L u

Preparatory and final time is determined

T p-z = a + bn n + cP p + dP pp

After calculating T in, it is adjusted depending on the serial production. Correction factor

k c ep = 4.17 [(Ta + Tv) n p + T p-z] -0.216,

where n p is the number of processed parts in the batch.

Preparatory and final time is determined as the amount of time: for organizational preparation; installation, preparation and removal of devices; adjustment of the machine and tool; trial run according to the program. The main characteristics that determine the preparatory and final time are the type and main parameter of the machine, the number of tools used in the program, offsets used in the operation, the type of fixture, the number of initial modes of the machine.

The rate of piece time per operation

T w = (T a + T ser) (1 + (a obs + a ex.l) / 100].

Time for organizational and Maintenance workplace, rest and personal needs,% of the operational time, are set depending on the basic parameters of the machine and the part, the worker's employment and the intensity of labor. It can partially overlap with the time of automatic operation of the machine; piece time in this case should decrease by 3%.

Automation of the processing and auxiliary work on CNC machines creates the prerequisites for the simultaneous maintenance of several machines by the operator. Carrying out of the operator's functions of servicing the workplace on one of the machines usually leads to interruptions in the operation of other machines being serviced. The time for rest increases due to the higher intensity of work in the conditions of multi-station service. The time of operational work in the norm of piece time increases due to the auxiliary time for transitions from machine tool to machine tool.

The time norm for performing operations on CNC machines when working on one machine (N BP) consists of the preparatory and final time norm (T PZ) and the piece time norm (T W)

where: Т ЦА - cycle time of automatic operation of the machine according to the program, min;

T B - auxiliary time for the operation, min;

and those, and org, and ex - time for technical and organizational maintenance of the workplace, for rest and personal needs with one-way service,% of the operational time;

K t in - a correction factor for the time of performing manual auxiliary work, depending on the batch of workpieces.

The cycle time of automatic operation of the machine according to the program is determined by the formula:

where: T O - main (technological) time for processing one part, min;

T MV - machine-auxiliary processing time according to the program (for the approach and withdrawal of the part or tool from the starting points to the processing zones; setting the tool to size, changing the tool, changing the value and direction of feed, the time of technological pauses, etc.), min ...

The main processing time is:

where: L i is the length of the path traversed by the tool or part in the direction of feed when processing the i-th technological section (taking into account the penetration and overrun), mm;

S mi - minute feed at a given technological section, mm / min.

The auxiliary time for an operation is defined as the sum of times:

where: T V.U - time for installation and removal of the part manually or with a lift, min;

T V.OP - auxiliary time associated with the operation (not included in the control program), min;

T V.IZM - auxiliary non-overlapping time for measurements, min;

Machine-auxiliary time associated with the transition, included in the program and related to the automatic auxiliary work of the machine, providing for the approach of a part or tool from the starting point to the processing zone and retraction; setting the tool to the size of the treatment; automatic tool change; turning the feed on and off; idle strokes during the transition from the processing of some surfaces to others; technological pauses provided for a sharp change in the direction of feed, checking dimensions, for inspecting the tool and reinstalling or re-fixing the part, is included as constituent elements during the automatic operation of the machine and is not separately taken into account.

The standards of the preparatory and final time are designed for setting up CNC machines for processing parts according to the embedded control programs and do not include additional programming actions directly at the workplace (except for machines equipped with operational software control systems).

The time rate for setting up the machine is represented as the time for preparatory and final work on the processing of a batch of identical parts, regardless of the batch, and is determined by the formula:

where: Т ПЗ - standard time for setting up and tuning the machine, min;

Т ПЗ 1 - the norm of time for organizational training, min;

Т ПЗ 2 - the norm of time for setting up a machine, a device, a tool, software devices, etc., min;

T PR.OBR - time norm for trial processing.

The time for receptions of preparatory and final work is set depending on the type and size group of equipment, as well as taking into account the features of the program control system and is subdivided into the time for organizational preparation; for setting up a machine tool, tool attachments, software devices; for a trial run through the program or trial processing of a part.

The composition of work on organizational training is common for all CNC machines, regardless of their group and model. Time for organizational preparation includes:

receiving an order, drawing, technological documentation, software carrier, cutting, auxiliary and control and measuring tools, devices, blanks before starting and handing them over after finishing processing a batch of parts at the workplace or in the tool store;

familiarization with the work, drawing, technological documentation, inspection of the workpiece;

instructing the master.

The composition of work on setting up a machine tool, tools and accessories includes methods of setting-up work, depending on the purpose of the machine and its design features:

installation and removal of the fastening device;

installation and removal of a block or individual cutting tools;

setting the initial operating modes of the machine;

installing the software carrier into the reader and removing it;

zero position adjustment, etc.