GB/T 23567.2-2018Reliability evaluation for numerical control machine tools—Part 2: Machining centres (English PDF)

3.1 Machining center

It is a CNC machine tool. The spindle is usually horizontal or vertical and has two or more machining methods (such as milling, boring, Drilling), through the machining program, automatic tool change from a magazine or similar storage unit. The machine can also be artificial within a certain range. control. [GB/T 6477-2008, definition 2.1.28]

3.2 Failure

The ability of the product to complete the required function is interrupted.

Note 1. After failure, the product is in a fault state.

Note 2. The difference between "failure" and "fault" is that the failure is an event and the failure is a state.

Note 3. The "failure" defined here does not apply to products consisting only of software. [GB/T 2900.13-2008, definition 191-04-01]

3.3 Design failure

Failure caused by improper product design. [GB/T 2900.13-2008, definition 191-05-09]

3.4 Manufacturing fault

Failure due to failure to manufacture the product in accordance with the design or specified process. [GB/T 2900.13-2008, definition 191-05-10]

3.5 Intermittent fault

Appears for a limited period of time, and subsequent failure of the product to restore the required function without any repairs.

Note: This type of fault is often reproduced. [GB/T 2900.13-2008, definition 191-05-17]

3.6 Failure mode

One of the possible states of a faulty product for a given requested function. [GB/T 2900.13-2008, definition 191-05-22]

3.7 Fault recognition

Identify faulty events. [GB/T 2900.13-2008, definition 191-07-20]

3.8 Failure cause

Factors that cause failure during design, manufacture, or use. [GB/T 2900.13-2008, definition 191-04-17]

3.9 Failure mechanism

A physical, chemical, or other process that causes failure. [GB/T 2900.13-2008, definition 191-04-18]

3.10 Conformity test

A test indicating whether a certain characteristic or a certain property of a product meets the stated requirements. [GB/T 2900.13-2008, definition 191-14-02]

3.11 Simulation field test

Compliance tests or test tests performed under specified and controlled conditions (with or without simulating actual field conditions).

Note: Rewrite GB/T 2900.13-2008, definition 191-14-04.

3.12 Tracking statistics field test

Compliance testing or testing conducted by tracking and statistical methods at the user site where work, environment, maintenance and measurement conditions are recorded Test.

Note: Rewrite GB/T 2900.13-2008, define 191-14-05.

3.13 Quick test

In order to shorten the controllability test process, under the working mechanism of the machine tool and the safety margin, the applied load level exceeds the normal work of the machine tool. Do a horizontal test.

4.1 Test plan

4.1.1 Test selection

The machine reliability test method, the simulation field test and the tracking and field test are optional.

4.1.2 Simulation field test

For newly developed and newer machine tools, a simulated field test with no replacement timing censoring test should be used. Simulated field test Should be a continuous reliability test.

4.1.3 Tracking Statistics Field Test

For mass-produced machine tools, time-crunting or fixed-crunch tracking statistical field tests should be used.

4.1.4 Retesting

If the test is stopped midway through various reasons, the test should be repeated.

4.2 Timing Censoring Test Time

4.2.1 Simulated field test in a fast mode, the cumulative test time of each sample machine is T>=200h.

Note: For non-quick tests, the cut-off time can be determined based on the machine's daily work shift and the purpose of the test.

4.2.2 The tracking and statistical field test is adopted, and the cumulative test time of each sample machine is T>=2000h.

4.3 Censoring test

The requirements for the end of the test using the censored method are in accordance with relevant regulations.

5.1 Test environment

Room temperature.

5.2 Pre-test

5.2.1 Before the test, the machine tool shall be pre-inspected according to the requirements of the instruction manual or technical documents. After the machine has passed the pre-inspection, it can be carried out. Rely on sex test.

5.2.2 Prior to the test, special handling of any quality aspects of the machine tool is not permitted.

5.3 Test equipment and instruments

5.3.1 The reliability test device used shall be safe and reliable and shall meet the test requirements.

5.3.2 The measuring instrument used shall be calibrated and within the calibration period.

5.4 Simulated field test

5.4.1 The actual working conditions of the machine tool should be simulated as much as possible.

5.4.2 The lubrication, cooling and other systems of the machine tool should be in normal working condition.

5.4.3 The test device should be placed in the middle of the workbench as much as possible and should be firm and reliable.

5.4.4 The toolies with the heaviest, longest and largest diameters should be installed in the tool magazine.

5.4.5 The test load spectrum and working condition spectrum shall be prepared according to the characteristics of the test machine.

5.4.6 When using a rapid test, the working principle of the machine tool, as well as the failure and failure mechanism should not be changed.

5.5 Tracking Statistics Field Test

5.5.1 The operating conditions of the machine tool shall be representative and conform to the product design or specification.

5.5.2 The selected prototype should be as similar as possible under similar operating conditions.

5.5.3 The machine tool shall be subjected to an early failure screening test.

5.5.4 All test machines shall have identification numbers.

5.6 Preventive maintenance

Normal preventive maintenance (if necessary replacement, adjustment, lubrication, etc.) is permitted during the test.

5.7 Failure Determination and Counting Principles

5.7.1 The principle of fault determination shall be in accordance with 4.1 of GB/T 23567.1-2009.

5.7.2 The counting principle of faults shall be in accordance with 4.2 of GB/T 23567.1-2009.

5.8 Sampling

5.8.1 The sampling principle shall be in accordance with 5.1 of GB/T 23567.1-2009.

5.8.2 The number of samples is randomly sampled in the product according to the sampling principle. The number of samples is as specified in Table 1.

6.1 Simulated field test

6.1.1 Test content

The test contents of the machine tool simulation field test are shown in Table 2.

6.1.2 Test procedure

6.1.2.1 Dry running test

6.1.2.1.1 CNC machine program according to GB/T 21012-2007, JB/T 8801-2017, JB/T 10793.3-2017 or enterprise Conduct a dry run test.

6.1.2.1.2 The test time for the dry running of the machine tool shall be at least 24h.

6.1.2.1.3 During the test, the coolant should be turned on.

6.1.2.2 Axis loading test

6.1.2.2.1 Under the simulated working state, load tests are performed on the machine X axis, Y axis and Z axis respectively.

6.1.2.2.2 The loading force, loading time and loading frequency shall be in accordance with the provisions of the load spectrum.

6.1.2.2.3 Operating parameters such as spindle speed and feed rate shall be as specified in the operating spectrum.

6.1.2.2.4 The loading time for each axis shall be at least 40h.

6.1.2.3 Static stiffness test of spindle system

6.1.2.3.1 After each axis is loaded, the static stiffness test of the spindle system is carried out.

6.1.2.3.2 Under the simulated working condition, the static stiffness loading test shall be carried out on the machine tool spindle in the three directions of X, Y and Z respectively (see Figure 1).

6.1.2.3.3 The loading force shall not exceed the maximum load specified in the design.

6.1.2.3.4 The loading force in each direction shall be loaded in three gears (light load, medium load, heavy load), and the loading force of each gear shall be repeated three times.

6.1.2.3.5 Record the elastic displacement values of the main shaft in the X-axis, Y-axis and Z-axis directions, draw the corresponding elastic displacement curve, and calculate the main The static stiffness of the shaft at maximum static load.

6.1.2.4 Spindle torque and power loading test

6.1.2.4.1 In the simulated working state, the torque loading test is carried out under the low speed operation of the machine; the power loading is performed under the high speed operation of the machine tool. test.

6.1.2.4.2 Loading force, loading time and loading frequency shall be as specified in the load spectrum.

6.1.2.4.3 Operating parameters such as spindle speed shall be as specified in the operating spectrum.

6.1.2.4.4 Torque loading and power loading time shall be at least 24h respectively.

6.1.2.5 Typical test piece cutting test

6.1.2.5.1 Test piece cutting test. The general machining center shall be in accordance with the provisions of GB/T 18400.7-2010, and the precision machining center shall be in accordance with GB/T 20957.7- According to the regulations of 2007, the high-precision machining center is in accordance with JB/T 10793.1-2007 or JB/T 10793.2-2007, or according to enterprise standards.

According to the provisions of the technical specifications, the precision test of the typical test piece is performed on the prototype.

6.1.2.5.2 The number of processed test pieces shall be determined by the tester and the manufacturer in consultation.

6.1.2.6 Enhanced air run test

6.1.2.6.1 Intensify measures based on the content of the dry run test, the setting of the NC program shall include. the spindle adopts medium speed and high speed Turn, increase the rapid movement of components and the high-speed running time of the spindle, increase the injection volume of the cooling liquid, increase the simulated cutting motion, and so on.

6.1.2.6.2 The idle test acceleration test time shall be at least 24h.

6.1.2.7 Safety test

6.1.2.7.1 Carry out relevant safety tests in accordance with the provisions of GB 5226.1-2008 and GB 18568-2001. Generally should include safety equipment Tests such as setting, interlocking devices, control devices, moving parts, tool magazines, automatic exchange devices, and chip removal devices.

6.1.2.7.2 The number of machine tool safety tests shall be at least 20 times, and the functional safety test shall be at least 10 times. The regulations are carried out.

6.1.2.8 Machine tool accuracy test

6.1.2.8.1 Geometric accuracy, positioning accuracy and repeat positioning shall be performed before the test, after each loading test phase, and after the end of the test. Accuracy test.

6.1.2.8.2 Geometric accuracy test. Ordinary machining center according to GB/T 18400.1-2010 or GB/T 18400.2-2010, precision According to GB/T 20957.1-2007 or GB/T 20957.2-2007, the high-precision machining center is according to JB/T 10793.1- The provisions of 2007 or JB/T 10793.2-2007, or according to the standards of enterprises and technical specifications.

6.1.2.8.3 Positioning accuracy and repeat positioning accuracy test. Ordinary machining center according to GB/T 18400.4-2010, precision machining According to the provisions of GB/T 20957.4-2007, the high-precision machining center is in accordance with JB/T 10793.1-2007 or JB/T 10793.2-2007. Set, or according to corporate standards, technical specifications.

6.2 Tracking Statistics Field Test

6.2.1 Generally, on-site tracking should be carried out when the product is put into use.

6.2.2 After the test is stopped, the performance of the prototype and the main safety functions shall be checked.

7.1 Simulation field test

7.1.1 The operation of the machine should be checked at any time during the test and recorded (see Table A.1 in Appendix A). Records should be accurate, where changes are made Wherever, there should be a record of the person's signature and a reason.

7.1.2 In the event of a fault, immediately stop the inspection, the inspector immediately records each fault and fills in the "fault record form" (see Table A.2) and the "Reliability Test Report" (see A.3).

7.1.3 During the test, the replacement of consumables and accessories that have reached the end of their life is not counted, but should be recorded.

7.2 Tracking statistics field test

7.2.1 Machine reliability field tracking test should have at least 2 data collection points.

7.2.2 Data collection may be performed by the tester or the organization user. When collecting data by users, the user should be trained to make the user clear Meaning of meaning, master the method of fault recording, and provide the user with the fault record table and fault analysis report of the machine tool.

7.2.3 The tester should regularly visit the user's site to understand the situation and provide guidance on specific issues, and should record and report the user on a regular or one-time basis. Responsible for recycling and responsible for saving.

8.1 Mean Time Between Failure MTBF Estimation

8.1.1 Mean time between failures The MTBF estimation is calculated as specified in equation (1).

In the formula:

k --- reliability factor;

Tj --- The cumulative working time of the jth machine in the assessment period, in hours (h);

Rgj --- The number of effective cumulative function failures of the jth machine tool in the evaluation period, in units;

Rsj --- The cumulative failure of the jth machine tool in the assessment period, in units of one;

n --- The number of prototypes, the unit is Taiwan.

8.1.2 The reliability factor k shall comply with the provisions of B.1 of Appendix B.

8.1.3 The number of failures rsj shall comply with the provisions of B.2.

8.2 Evaluation of reliability test results

It shall be carried out in accordance with the provisions of Chapter 12 of GB/T 23567.1-2009.

A.1 Reliability test operation record

The machine reliability test operation record is shown in Table A.1.

Note: Fill out a form for each product and the form can be continued.

A.2 Reliability test failure record

The machine reliability test failure record is shown in Table A.2.

Note: Fill out a form for each product and the form can be continued.

A.3 Reliability Test Report

The model of the machine reliability test report is shown in Table A.3.

B.1 Reliability coefficient k

B.1.1 Calculation of reliability coefficient k

The reliability coefficient k is calculated as specified in equation (B.1).

k=kz·ks·kq (B.1)

In the formula:

Kz---manufacturing coefficient;

Ks---test coefficient;

Kq---enhancement coefficient.

B.1.2 Reliability Manufacturing Factor kz

B.1.2.1 The reliability manufacturing factor kz is calculated according to the formula (B.2).

Kz=kz1·kz2·kz3 (B.2)

In the formula:

Kz1---CNC axis coefficient;

Kz2---assembly coefficient;

Kz3---assembly environment factor.

B.1.2.2 The reliability manufacturing factor kz is selected in accordance with Table B.1.

B.1.3 Reliability test coefficient ks

B.1.3.1 The calculation of ks is as specified in equation (B.3).

Ks=ks1·ks2·ks3·ks4·ks5·ks6 (B.3)

In the formula:

Ks1---force load factor;

Ks2---torque load factor;

Ks3---loading time factor;

Ks4---spindle speed coefficient;

Ks5---spindle start and stop coefficient;

Ks6---Changing frequency factor.

B.1.3.2 The reliability test coefficient ks is selected in accordance with Table B.2.

B.1.4 Reliability enhancement coefficient kq

The reliability enhancement coefficient kq is set to 5.3.

B.2 Failure number rs

B.2.1 Calculation of the number of failures rs

The calculation of the number of failures rs is as specified in equation (B.4).

In the formula:

Rs1--- geometric accuracy failure; […]