GB/T 3808-2018Verification of pendulum-type impact testing machines (English PDF)

3.1 Terms relating to testing machines

3.1.1 Anvil

The portion of the test machine that is used to properly position the sample relative to the impact blade and the sample holder and support the sample under impact.

3.1.2 Base

The portion of the test machine frame below the horizontal support surface of the sample holder.

3.1.3 Strike center

a point on the pendulum, the effect of striking the specimen at that point and the total mass of the pendulum if concentrated at that point The effects of the strike are the same (see Figure 4).

Note: When the single pendulum strikes through the strike center along the horizontal line, the pendulum axis does not produce a horizontal reaction force.

3.1.4 Blow point

Place a specimen or equivalent gauge with a height of half the standard height (ie 5 mm) on the specimen holder, and punch the pendulum in the free suspension position.

The point on the blade that is in contact with the upper level of the specimen or gauge (see Figure 4).

3.1.5 Work test machine

Testing machines for metal materials testing in industrial, general laboratories or most research laboratories.

Note 1. These test machines are not used to establish standard values.

Note 2. The working test machine is tested using the method specified in this standard.

3.1.6 Standard test machine

A testing machine for determining the energy absorption calibration value of each batch of standard samples.

3.1.7 Impact blade

The portion of the pendulum that contacts the specimen (see Figure 2).

Note: The impact blade of the actual contact sample can have a 2mm radius (2mm impact edge) or a 8mm radius (8mm impact edge).

3.1.8 Sample holder

The part of the test machine used to position the specimen correctly with respect to the pendulum strike center, the impact edge and the anvil (see Figures 2 and 3).

3.2 Terms related to energy

3.2.1 Total absorbed energy

The total absorbed energy required to break the specimen using a test machine that has not been corrected for any energy loss.

Note: This energy is equal to the difference between the potential energy of the pendulum at the initial position and the potential energy at the end of the first half-swing period after the pendulum swings (see 6.3).

3.2.2 Initial potential energy

Potential energy. The difference between the potential energy of the initial position before the pendulum is released and the potential energy of the pendulum at the impact position measured by the direct test method.

Note: See 6.4.2.

3.2.3 Absorbing energy

The energy required to break the specimen using a test machine that has been corrected for frictional energy loss.

Note: The letters V and U are used to indicate the geometry of the gap, such as KV or KU. The number under the corner 2 or 8 is used to indicate the radius of the impact blade. Such as KV2.

3.2.4 Calculating energy

Kcalc. The value of the energy calculated from the angle, length and force values measured by the direct test method.

3.2.5 Initial potential energy nominal value

Energy nominal. The energy value given by the test machine manufacturer.

3.2.6 Absorption energy indication

The test machine indicates the energy value indicated by the device. The indication value may be that the friction energy loss of the measured absorption energy value K is required to be repaired.

A positive value can also be a value that does not need to be corrected.

3.2.7 Standard absorbed energy

The calibration value of the absorbed energy given to the standard sample for testing the performance of the test machine.

3.3 Terminology related to the sample

3.3.1 Height

The distance between the face with the notch and the face opposite it.

3.3.2 Width

A dimension parallel to the notch and perpendicular to the height direction.

3.3.3 Length

The largest dimension perpendicular to the direction of the notch.

3.3.4 Standard sample

By comparing the measured value of the absorbed energy measured by the testing machine with the standard absorbed energy value indicated by the impacted standard sample, for testing Suitable for impact test specimens.

Note: Standard samples are prepared in accordance with the requirements of GB/T 18658.

6.1 General requirements

The items directly tested by the testing machine are as follows:

a) foundation and/or installation;

b) the rack;

c) pendulum, including the hammer and the impact blade;

d) anvil and support;

e) indicating device.

6.2 Basic and/or installation

6.2.1 The basis for fixing the test machine and the method of fixing the test machine to the foundation are very important.

6.2.2 After the test machine is installed, the foundation cannot usually be inspected. Therefore, technical documents should be provided during installation to ensure that the quality of the foundation is not less than 40 times the mass of the pendulum.

6.2.3 Testing of test machine installation shall include the following:

a) Ensure that the bolts are tightened to the torque values specified by the manufacturer. This torque value should be given in the technical documentation provided by the manufacturer (see 6.2.1). If the user uses or chooses other methods to install, it should be guaranteed to achieve the effect of installation according to the above torque value;

b) When performing the impact test, ensure that the test machine is not subject to external vibrations from the foundation.

Note: For example, placing a small container filled with water in the proper position of the rack indicates that this requirement is met if the surface of the water does not fluctuate.

6.3 Rack

6.3.1 The inspection of the rack (see Figure 1) shall include the following items:

a) the free hanging position of the pendulum;

b) the position of the pendulum relative to the support;

c) axial clearance and radial clearance of the pendulum bearing;

d) The distance between the hammer and the frame.

The test machine manufactured after the publication of this standard shall have a reference surface as a reference point for measurement. Appendix C gives an angle gauge A direct test method for detecting the geometrical characteristics of the test machine.

6.3.2 The parallelism between the axis of the pendulum shaft and the reference plane should be within 2/1000. The manufacturer shall give the test results of the project in the certificate.

6.3.3 When installing the test machine, the level of the datum should be within 2/1000. For test machines without a reference plane, the pendulum shaft should be directly The level of the axis is adjusted to within 4/1000, or a reference plane capable of verifying the level of the axis of the pendulum shaft is specified as described above.

6.3.4 When the pendulum is freely suspended, the clearance between the impact blade and the specimen shall be within 0.5 mm.

Note: The gap between the impact edge and the gauge can be measured using a rectangular cross-section gauge of approximately 55 mm in length, 10.5 mm in height 1) and approximately 10 mm in width (see Figure 3).

6.3.5 The angle of the pendulum swing plane relative to the axis of the pendulum shaft shall be 90 ° ± 0.1 °.

6.3.6 The impact blade should be completely in contact with the entire width of the specimen.

Test method for this article. The sample of size 55mm × 10mm × 10mm is tightly wrapped with thin paper (such as tape) and placed on the sample holder. The impact blade is also tightly wrapped with carbon paper with the carbon side facing outward (ie, the carbon surface does not face the impact edge). lift The oscillating weight is placed at a small angle of a few degrees from the free hanging position, then released and brought into contact with the specimen only once. Carbon paper in parcel A completely cross-cut impression should be left on the paper of the sample. This test can simultaneously detect the angle between the impact blade and the sample (see 6.4.8).

6.3.7 When installing the pendulum, the center of the impact blade should coincide with the center of the span of the two anvils, and the maximum allowable phase difference is 0.5mm.

6.3.8 When the position of the pendulum strike point shown in Fig. 4b) is applied to a lateral force equal to 4% of the effective gravity Fg of the pendulum, it is measured at the impact edge. The axial clearance of the pendulum bearing should not exceed 0.25 mm.

6.3.9 Radial clearance of the shaft at the pendulum shaft bearing when a force of 150 N ± 10 N is applied in a direction of distance l and perpendicular to the plane of the pendulum oscillation Should not be greater than 0.08mm.

Note: For example, when a pendulum is applied with a force of approximately 150 N in a direction perpendicular to the plane of the yaw, the dial indicator fixed to the pedestal housing can be used to indicate the shaft The amount of movement of the end (on the bearing) to measure the radial clearance.

6.3.10 For newly manufactured test machines, it is recommended that the mass of the frame base be at least 12 times the mass of the pendulum.

Note: The base of the test machine refers to the part of the frame below the horizontal support surface of the sample holder.

1) The value of the international standard ISO 148-2:2008 is 9.5mm, which is not convenient for testing. […]