This standard specifies the tolerances for the inspection of the positioning accuracy of the linear and rotary axes of machining centers. This standard applies to machining centers with linear axis travel up to 2000 mm and ordinary precision of rotary axes. JB/T 8771.4-1998 Inspection conditions for machining centers Part 4: Inspection of positioning accuracy and repeatability of linear and rotary axes JB/T8771.4-1998 Standard download decompression password: www.bzxz.net

JB/T 8771. 4—1998
This standard is formulated based on the draft international standard ISO/DIS10791-4.2 "Test conditions for machining centers Part 4 Positioning accuracy and repeatability of linear and rotary axes". It is equivalent to the draft international standard in terms of technical content. This standard has the following differences from ISO/DIS10791-4.2: According to my country's national conditions, Chapter 6 of ISO/DIS10791-4.2 "Recorded information" is changed to "Recommended recorded information". This standard is one of the series of standards for inspection conditions of machining centers. This series of standards includes the following 13 parts, which can be used simultaneously or separately:
Part 1: Geometric accuracy inspection of horizontal and attached spindle heads (horizontal B axis) Part 2: Geometric accuracy inspection of vertical machining centers Part 3: Geometric accuracy inspection of integral universal spindle heads with horizontal main rotary axes (vertical Z axis) (to be formulated) Part 4: Positioning accuracy and repeatability inspection of linear and rotary axes Part 5: Positioning accuracy and repeatability inspection of workpiece holding pallets Part 6: Test of feed rate, speed and interpolation accuracy (to be formulated) Part 7: Test of precision of finished test piece
Part 8: Evaluation of spherical shape by circular test method (to be formulated) Part 9: Evaluation of tool change and pallet change action time (to be formulated) Part 10: Evaluation of thermal deformation (to be formulated) Part 11: Evaluation of noise emission (to be formulated) Part 12: Evaluation of vibration intensity (to be formulated) Part 13: Evaluation of safety measures (to be formulated) This standard is proposed and managed by the National Technical Committee for Standardization of Metal Cutting Machine Tools. The drafting units of this standard are Changzheng Machine Tool Co., Ltd., Beijing Machine Tool Research Institute, Beijing Milling Machine Research Institute, and Shenyang Boring and Drilling Machine Research Institute. The main drafters of this standard are Wang Xiaohui, Cheng Jinjiang, Hu Ruilin, and Liu Chunhe. 558
JB/T8771.4-1998
ISOForeword
ISO (International Organization for Standardization) is a federation of national standardization organizations (ISO members) around the world. The development of international standards is usually done by ISO's technical committees. Each ISO member interested in a topic established by a technical committee has the right to express its opinion in the technical committee. International organizations, official or non-official organizations associated with ISO may also participate in this work. ISO works closely with the International Electrotechnical Commission (IEC), which is responsible for electrical standards. Draft international standards accepted by the technical committee are sent to each member for comments and then voted on. The publication of international standards requires at least 75% of the members to vote.
ISO 10791-4 was developed by ISO/TC 39
Machine Tools Technical Committee.
1 Scope
Machinery Industry Standard of the People's Republic of China
Test conditions of machining centresPart 4 : Accuracy and repeatabilityof positioning of linear and rotary axesThis standard specifies the tolerances for positioning accuracy inspection of linear and rotary axes of machining centres. JB/T8771.4—1998
This standard is applicable to machining centres with linear axis stroke up to 2000mm and ordinary accuracy of rotary axis. 2 Referenced standards
The clauses contained in the following standards constitute the clauses of this standard by reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T17421.1--1998 General Rules for Inspection of Machine Tools Part 1: Geometrical Accuracy of Machine Tools under No-load or Finishing Conditions ISO230-2:1997 General Rules for Inspection of Machine Tools Part 2: Determination of Positioning Accuracy and Repeated Positioning Accuracy of Axis of CNC Machine Tools 3 General Requirements
3.1 In this standard, all linear dimensions and corresponding tolerances are expressed in millimeters (mm); angular dimensions and corresponding tolerances are expressed in degrees (), microradians μrad) and seconds (\). The conversion relationship is as follows: 0.010/1000-10×10°=10 μrad~2\3.2 When using this standard, reference must be made to the provisions of ISO230-2, especially the inspection conditions, inspection procedures and evaluation of results. 3.3 The order of inspection items in this standard does not represent the actual inspection order. In order to facilitate the assembly and disassembly of inspection tools and inspection, inspections can be carried out in any order.
3.4 ​​When inspecting machine tools, not all items in this standard must be inspected due to structural characteristics. When inspection is required for acceptance purposes, the user may obtain the manufacturer's consent to select some inspection items of interest, but these inspection items must be clearly stated when ordering the machine tool. 3.5 The inspection tools specified in this standard are only examples. Other inspection tools with the same indication and at least the same accuracy can be used. The indicator should have a resolution of 0.001mm or higher. 3.6 Moving parts on non-detection axes are placed in the middle of their stroke. Sliding spindles, slides, etc., when they are auxiliary axes, should be kept in the retracted position.
3.7 Each linear and rotary axis must be inspected. 4 Positioning of linear axes
4.1 Tolerances
As defined in Chapter 2 of ISO230-2:1997, Table 1 gives the positioning tolerances for different measuring strokes of machining centers with a stroke up to 2000 mm. Approved by the State Machinery Industry Bureau on July 17, 1998 560
Implementation on December 1, 1998

Inspection Items
Bidirectional Positioning Accuracy
Unidirectional Positioning Accuracy
Bidirectional Repeat Positioning Accuracy
Unidirectional Repeat Positioning Accuracy
Reverse Difference of Axis
Average Reverse Difference
Bidirectional Positioning System Deviation
Unidirectional Positioning System Deviation
JB/T 8771. 4—1998
Table 1 Tolerance of Positioning Accuracy of Linear Axis
Ａ和Ａ+
R和Ｒ+
E+和Ｅ+
Average Bidirectional Positioning Deviation Range of Axis
Note: The symbol indicates positive approach, and the symbol indicates negative approach. Inspection Tools
Laser interferometer, or other measuring systems with similar accuracy can be used. Refer to ISO230-2 and notes
Axis measurement travel
>500～~800
>800～1 250>1 250~2 000
When using laser interferometer, appropriate protective measures should be taken in accordance with A13 of GB/T17421.1--1998. Regarding the execution of the inspection, the process specified in 4.3.2 of ISO230-2:1997 should be followed. 4.4 See Table 2 for an example of the calculated deviation table. Tabular form of inspection results
Measurement name
Bidirectional positioning accuracy A
Positioning accuracy (positive) A
Positioning accuracy (negative)
Bidirectional repeat positioning accuracy R
Repeat positioning accuracy (positive)
Repeat positioning accuracy (negative)
Reverse difference of axis B
Average reverse difference B
Bidirectional positioning system deviation E
Fixed Positioning system deviation (positive) E
Positioning system deviation (negative) E
Average bidirectional position deviation range of the axis M
Measurement stroke and results
Positioning of rotary axis
5.1 Tolerance
JB/T8771.4—1998
As defined in Chapter 2 of ISO230-2:1997, Table 3 gives the positioning tolerances of the machining centre with a measuring stroke of up to 360°. Table 3 Positioning tolerance of rotary axis
5.2 Inspection tools
Inspection items
Bidirectional positioning accuracy
Unidirectional positioning accuracy
Bidirectional repeat positioning accuracy
Unidirectional repeat positioning accuracy
Maximum reverse difference
Average reverse difference
Bidirectional positioning system deviation
Unidirectional positioning system deviation
Average bidirectional position deviation range of axis
Code and symbol
A* and A
RI and R
E+ and E+
Laser angle interferometer with indexing table, autocollimator with polyhedron, or other measuring system with similar accuracy can be used.
5.3 Refer to ISO230-2 and remarks
When using a self-propelled straightener, appropriate protective measures should be taken in accordance with A11 of GB/T17421.1-1998. Regarding the execution of the inspection, the process specified in 4.3.4 of ISO230-2:1997 should be followed. 5.4 An example of a table of calculated deviations is shown in Table 4. Table 4
Tabular form of inspection results
Measurement name
Bidirectional positioning accuracy A
Positioning accuracy (positive) A↑
Positioning accuracy (negative)
Bidirectional repeat positioning accuracy R
Repeat positioning accuracy (positive)
Repeat positioning accuracy (negative)
Reverse difference B of the axis
Average reverse difference B
Bidirectional positioning system deviation E
Positioning system deviation (positive)
Positioning system deviation Difference (negative)
Average two-way position deviation range of axis
Measurement stroke (°) and result (\)
Recommended information to be recorded
6.1 Information to identify the machine tool
a) Manufacturer’s name;
b) Design year (if available); c) Model and serial number;
JB/T8771.4—1998
d) Machine tool structure type in accordance with JB/T8771.1 and JB/T8771.2 (if possible). 6.2 Information to identify the inspection
a) Inspection date and place;
b) Name of company and inspector;wwW.bzxz.Net
c) List of inspection equipment used, including manufacturer’s name, model and serial number of components (e.g. laser head, optical components, temperature sensor).
6.3 Information on the test conditions
a) machine tool parts moving along or around the axis during the test; b) feed rate;
c) location of the measuring line;
d) number and location of temperature sensors;
e) temperature sensor readings immediately before and after the test; f) expansion coefficient used for material compensation;
g) air temperature, pressure and humidity (if relevant) immediately before and after the test; h) type of compensation applied to the machine tool axis; i) type of compensation applied to the measured data. 563
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