JPH0355092Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Field of industrial application] This invention is particularly useful for the chuck that holds the test piece of a universal testing machine that can perform not only tensile tests but also compression tests, transverse bending tests, bending tests, etc. This invention relates to a chuck for a universal testing machine that can reliably and safely obtain test data when a tensile test is performed up to the breaking point by combining a breaking extensometer with the test.

[Prior art]

Conventionally, the chuck for gripping a test piece in a universal testing machine has a grip built into a square hole with a taper provided in the crosshead, and a pinion is rotated against the rack formed in the grip to align the grip along the tapered surface. By moving the test piece up and down, the test piece is held between the opening of the square hole on the tensile test space side.

[Problem that the invention attempts to solve]

When a test piece is held between the conventional chucks configured as described above and a tensile test is performed up to the breaking point,
At the moment the test piece breaks, the reaction of the tensile load applied to the test piece acts on the chuck side. As a result, the chuck, which was being held between the upper crossheads, was pushed up a little by the reaction force, and the holding force weakened, causing it to fall.
In particular, since only short specimens can be taken from castings,
There are few clamping parts in the chuck, and if it breaks, there is a very high chance that it will fall.

Therefore, when not only measuring stress using a universal testing machine but also measuring elongation between the gauges of a test piece in combination with a fracture extensometer, the fractured test specimen may fall and cause damage to the fracture extensometer. Since the arm would be struck and damaged, such elongation measurements could not be carried out reliably and safely.

In addition, the shock when the tube breaks is transmitted to the chuck as well as to the main body of the tester, which adversely affects stable measurements.

The chuck for a universal testing machine according to this invention can prevent the danger of the clamping force being reduced by the chuck at the moment of rupture, and the definite test piece falling, when a conventional chuck performs a tensile test up to the breaking point. ,
It can also absorb shock and eliminate its effect on the testing machine itself, improving test safety, efficiency, and measurement accuracy. It can also be used for short test pieces such as castings. The purpose is to provide a chuck for a universal testing machine that can increase the versatility of the testing machine.

[Means for solving problems]

The chuck for a universal testing machine according to this invention is installed in each of the upper and lower crossheads of the universal testing machine, and is housed in a square hole whose inner surface is tapered so that the opening on the tensile test space side is narrow. A pair of grips that can be moved vertically along the inner circumferential surface of a square hole by a combination of a rack and a pinion, a pressing tool that presses the grips with the elastic force of a compression spring, and an end of the compression spring. and a fastener that tightens and fixes the grip with the compression spring pressed against the grip.

[Effect]

Therefore, the gripping tool is narrowed along the tapered surface of the square hole of the crosshead using the rack and pinion, and after gripping the test piece located in the tensile test space, the compression spring and the pressing tool are tightened with the fastener. For example, the pressing tool continues to apply pressure to the grip due to the elastic force of the spring compressed by the fastener, so even if the test piece breaks during a tensile test, the shock will prevent the grip from loosening toward the open side. . In addition, the shock of the breakage is absorbed by the compression spring and is not transmitted to the testing machine body.

〔Example〕

FIG. 1 is a perspective view showing the overall appearance of a universal testing machine incorporating a chuck, which is an embodiment of this invention, and FIG. 2 is a sectional view showing the configuration when incorporated into the universal testing machine. In Figure 2, the upper diagram shows the upper crosshead 2 of the universal testing machine, and the crosshead is installed in a square hole with a tapered inner surface so that the opening on the tensile test space 4 side is narrow. The lower figure shows a cross section of the lower crosshead 3 including the chuck, the left figure shows the chuck when it is open, and the right figure shows the chuck when it is closed. In the same figure, each crosshead 2,
The opening/closing operation of the grip 7, which moves up and down along the tapered surface of the square hole provided in 3, is performed by a pinion connected to the handles 5 and 6 shown in FIG. This is done by rotating.

A mounting plate 8 is fixed to the wide openings of the square holes of the crossheads 2 and 3, and a nut 9 is inserted into the center hole of the mounting plate 8 and fixed to the mounting plate 8. The tip side of the bolt 10 with a hole that is screwed into the nut 9 has a built-in pressing tool 12 that comes into contact with the grip 7 and a compression spring 13 that comes into contact with this.
The end of the compression spring 13 comes into contact with the tip of the bolt 10 with a hole, and the bolt 10 with a hole is tightened by a rotating rod 11 attached to its head, thereby compressing the spring 13. Due to the elastic force of the compression spring 13, the pressing tool 12 presses the gripping tool 7 that comes into contact with it. In addition, a hole is also formed in the center of the pressing tool 12, and a bolt with a hole 10 and a compression spring 1 are formed.
3. A communication hole communicating with the tensile test space 4 through the pressing tool 12 and the gripping tool 7 is formed.

In the universal testing machine chuck configured as above, when gripping a test piece, use the hole bolt 1
0, the pressing tool 12 presses the gripping tool 7, so even if the test piece breaks during the tensile test, especially on the upper crosshead 2 side,
The gripping tool 7 does not retreat due to the shock of breakage as in the conventional case, and the specimen remains gripped without falling. Therefore, even when an elongation test is performed in combination with an automatic extensometer as shown in FIG. 3, the risk of the test piece falling and damaging the extensometer arm 14, which is conventional, can be prevented. Furthermore, after the rupture test is completed, if the rupture test piece held by the lower crosshead 3 is unfastened by the socket bolt 10 and the chuck force of the grip 7 is weakened, the communicating hole formed as described above can be removed. It can be collected by falling through. Further, the shock of the test piece breaking is absorbed by the compression spring 13, thereby preventing any adverse effects on the main body of the tester.

(Effects) The chuck for a universal testing machine according to this invention is configured and operates as described above, so it can be used for tests such as tensile tests as a universal testing machine, and when combined with an automatic extensometer, it can be used to prevent falling test pieces. It is possible to perform safe and reliable testing by preventing this, and expand the applicability of the testing machine.
In particular, the test can be performed reliably even on short test pieces such as castings, and there is no need to configure a special testing machine, making it possible to provide a testing machine that is not only versatile but also economical. In addition, there is no need to pay attention to the handling of the fracture test piece, and testing efficiency can be improved. Furthermore, since the fracture shock is not transmitted to the testing machine itself, it has the effect of improving testing accuracy.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the appearance of the universal testing machine main body. FIG. 2 is a sectional view showing the structure of a chuck for a universal testing machine, which is an embodiment of this invention, which is incorporated into the crosshead of a universal testing machine. FIG. 3 is a diagram showing a state in which a universal testing machine is combined with an automatic extensometer to perform a tensile test. 2, 3...Crosshead, 3...Tensile test space, 7...Gripper, 9...Nut, 10...Bolt with hole, 12...Press tool, 13...Compression spring.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. The tester is installed in each of the upper and lower crossheads of a universal testing machine, and is housed in a square hole whose inner surface is tapered so that the opening on the tensile test space side is narrow. A set of grips that can be moved vertically along the inner circumferential surface of the hole by a combination of a rack and a pinion, a pressing tool that presses the grips with the elastic force of a compression spring, and an end of the compression spring. A chuck for a universal testing machine consisting of a fastener that abuts against the grip and tightens and fixes the compression spring in a state where it is pushed into the grip. 2. The chuck for a universal testing machine according to claim 1 of the utility model registration claim, in which a communication hole communicating with the tensile test space is formed in the center of the pressing tool and the fastening tool.