GB/T 6473-2023 Vertical surface broaching machines - Testing of the accuracy
1 Scope
This document specifies the naming, geometric accuracy inspection, working accuracy inspection and corresponding tolerance requirements of parts and axes of normal- accuracy vertical surface broaching machines.
This document applies to the verification of the accuracy of the broaching machine. It does not apply to the operational testing of the broaching machine (e.g. vibration, abnormal noise, stick-slip motion of components), nor to broaching machine characteristics (e.g. speeds, feeds).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 17421.1-2023 Test code for machine tools - Part 1 : Geometric accuracy of machines operating under no-load or quasi-static conditions (ISO 230-1:2012, IDT)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 17421.1-2023 and the following apply.
Note: ISO and IEC maintain terminological databases for use in standardization at the following addresses:
- ISO Online browsing platform: available at https://www.iso.org/obp
- IEC Electropedia : available at http://www.electropedia.org/
3.1
surface broaching operation
machining process in which a broach is pushed over an external surface to remove material by linear cutting
Note: Principal cutting motion is a relative translation of broach against the non-rotating workpieces and where the cutting energy is brought by the broach or workpiece motion.
3.2
broach
cutting tool that has multiple transverse cutting edges each with progressively increased size
3.3
broaching machine
machine tool in which broaching operation is executed
3.4
vertical surface type broaching machine
vertical broaching machine in which its broach is pushed or pulled over an external surface of the workpiece to remove material
Note: A vertical broaching machine is understood to be a broaching machine whose main cutting axis (Z-axis) is vertical.
4 Designation of parts and axes
The designation of the parts and axes of the vertical external broaching machine are illustrated in the typical example of Figure 1.
5 General
5.1 Measurement units
In this document, all linear dimensions, deviations and corresponding tolerances are expressed in millimetres and angular dimensions are expressed in degrees. Angular deviations and the corresponding tolerances are expressed in ratios as the primary method. However, in some cases, microradians or arcseconds may be used for clarification purposes. Formula (1) is used for conversion of the units of angular deviations or tolerances:
5.2 Standard applied
To apply this document, reference shall be made to GB/T 17421.1-2023, for the installation and levelling of the machine before testing, warming up of the moving components, measuring methods and recommended uncertainty of testing equipment.
In the “Observations” block of the tests described in the following clauses, the instructions are followed by a reference to the corresponding clause in GB/T 17421.1-2023, in cases where the test concerned is in line with the specifications of GB/T 17421.1-2023.
5.3 Testing sequence
The sequence in which the tests are presented in this document does not define the practical order of testing. In order to make the mounting of instruments or gauging easier, tests may be performed in any order:
5.4 Tests to be performed
Prior to conducting tests on a vertical surface type broaching machine, the machine shall be levelled according to the recommendations of the manufacturer/supplier (see GB/T 17421.1-2023, 6.1.2).
When testing a machine tool, it is not always necessary or possible to carry out all the tests described in this document. When the tests are required for acceptance purposes, it is up to the user to choose, in agreement with the manufacturer/supplier, those tests relating to the components and/or the properties of the machine tool which are of interest. These tests are to be clearly stated when ordering a machine tool. A mere reference to this document for the acceptance tests, without specifying the tests to be carried out, and without agreement on the relevant expenses, cannot be considered as binding for any contracting party.
5.5 Tolerances
In this document, all tolerance values are guidelines. When they are used for acceptance purposes, other values can be agreed on between the user and the manufacturer/supplier. The required/agreed tolerance values are to be clearly stated when ordering the machine.
When establishing the tolerance for a measuring length different from that given in this document, it shall be taken into consideration that the minimum value of tolerance is 0.010 mm.
5.6 Measuring instruments
Measuring instruments indicated in the tests described in the following clauses are examples only. Other instruments capable of measuring the same quantities and having the same or a smaller measurement uncertainty may be used. Reference shall be made to GB/T 17421.1-2023, Clause 5, which indicates the relationship between measurement uncertainties and the tolerances.
When a “dial gauge” is referred to, it can mean not only dial test indicators (DTI) but any type of linear displacement sensor such as analogue or digital dial gauges, linear variable differential transformer (LVDTs), linear scale displacement gauges, or non-contact sensors, when applicable to the test concerned
See GB/T 17421.1-2023, Clause 4.
When a "straightedge" is referred to, it can mean any type of straightness reference artefact, such as a granite or ceramic or steel or cast iron straightedge, one arm of a square, one generating line on a cylindrical square, any straight path on a reference cube, or a special, dedicated artefact manufactured to fit in the T-slots or other references.
In the same way, when a “square” is mentioned, it can mean any type of squareness reference artefact, such as a granite or ceramic or steel or cast-iron square, a cylindrical square, a reference cube, or, again, a special, dedicated artefact.
5.7 Diagrams
For reasons of simplicity, diagrams in this document illustrate only one type of machine.
5.8 Axes not under test
During the execution of some geometric tests on one axis of motion, the position of the other axes, not under test, may affect the results. Therefore, the positions of these axes, as well as the offsets on the tool side and on the workpiece side, are to be recorded in the test report.
