JPH1019752A - Material testing machine - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To grasp a test piece by effectively utilizing a gripping surface of a gripping tooth without confirming an actual gripping state of the test piece. SOLUTION: A pair of three gripping teeth for gripping a test piece TP are provided inside the crosshead 1 in a state where they are not visible from the outside. The test piece TP is inserted and arranged between the pair of grip teeth 3, and the test piece TP reaches the upper end of the grip tooth 3 along the load axis, and the light emitted from the light emitting element 9 is blocked. The light is not detected by the light receiving element 8. After confirming this, a load is applied to the test piece TP.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material testing machine provided with a pair of gripping teeth for holding a test piece inside a crosshead.

[0002]

2. Description of the Related Art Conventionally, after a test piece is arranged between a pair of gripping teeth opened at a predetermined interval, the gripping teeth are opened and closed, the test piece is sandwiched between these gripping teeth, and the test piece is held. Grasping.

For example, as shown in FIG. 3, a pair of gripping teeth 101 are respectively held by holders 102, are built in a crosshead 103, and are arranged between liners 105 on a tapered surface 104. Grab tooth 101 is liner 1
It is openably guided by 05. Drive shaft 106
Has a helical pinion 108 meshed with a rack 107 of the holder 102, and is rotatably supported. In the opening / closing mechanism of the gripping teeth 101 configured as described above, in order to grip a test piece between the gripping teeth 101, a drive motor (not shown) is driven to rotate the drive shaft 106 by a predetermined angle, so that the rack 107 is rotated. And the helical pinion 108 grasps the rotational movement of the drive shaft 106 and
1 linear motion. Thereby, the gripping teeth 10
1 linearly moves integrally with the holder 102. And
The holder 102 slides along the liner 105, the gripping teeth 101 are closed by the wedge action of the taper 104 surface, the test piece is gripped between the gripping teeth 101, and the drive shaft 1
When 06 is reversed, the grip 101 is opened and the test piece is opened.

[0004]

By the way, in such a material testing machine, the gripping teeth are provided inside the crosshead and have a structure which cannot be seen from the outside, so that the mounting state of the test piece cannot be confirmed.

Therefore, the test piece holding surface of the gripping teeth may not be used effectively, and the test may be started without sufficiently holding the test piece, which may cause chuck slip. In addition, since the gripping force is concentrated on a part of the test piece, the test piece may be broken in the chuck. Furthermore, since the gripping force acts locally on the gripping surfaces of the gripping teeth, wear and damage are concentrated, and the durability is significantly reduced.

The present invention has been devised to solve the above-mentioned problems in a material testing machine, and provides a material testing machine capable of gripping a test piece by effectively using a gripping surface of a gripping tooth. The purpose is to:

[0007]

In the material testing machine according to the present invention, a pair of gripping teeth for gripping a test piece are provided inside a crosshead in a state where they are not visible from the outside.
These gripping teeth are provided with sensors for detecting the gripping state of the test piece, that is, detecting that the upper gripping tooth has reached the upper end and the lower gripping tooth has reached the lower end, in the vicinity of the gripping teeth, respectively. . As a sensor for detecting such a test piece, a sensor that includes a light emitting element and a light receiving element and detects light blocking, a sensor that detects reflected light, and a limit switch that detects by contact may be used. .

[0008]

FIG. 1 is a schematic configuration diagram of a material testing machine according to the present invention. Reference numeral 1 denotes a crosshead, which is configured to slide up and down on the column 2. The support 2 is a screw rod, and a screw mechanism meshed with a nut provided on the crosshead 1 rotates the screw rod or the nut to rotate the crosshead 1.
There is something that moves up and down.

Further, inside the crosshead 1, a pair of gripping teeth 3 are provided with a holder 4 and a gripping tooth pressing plate 7 respectively.
The holders 4 are disposed between the liners 6 on the surface of the taper 5, and are guided by the liners 6 so as to be openable and closable. As in FIG. 3, a drive shaft (not shown) having a helical pinion (not shown) engaged with a rack (not shown) provided on the holder 4 is rotatably supported. When the rack and helical pinion rotate at a certain angle, the rotation of the drive shaft
, The gripping teeth 3 linearly move integrally with the holder 4, the holder 4 slides along the liner 6, and the wedge action of the tapered surface 5 closes the gripping teeth 3, and the gripping teeth 3 The test piece TP is gripped in between. Also,
When the drive shaft is reversed, the gripping teeth 3 are opened and the test piece TP
Is released. The rotation of the drive shaft may be performed by using a human power by providing a handle or the like, or may be performed by using a hydraulic motor and an electric motor.

Further, a light emitting element 9 is provided on an upper end face of one of the gripping teeth 1 and a light receiving element 8 is provided on an upper end face of the other gripping tooth 1.
Are provided in a space provided in the middle of the grasping tooth presser plate 7 and are arranged so that the light emitted from the light emitting element 9 is received by the light receiving element 8 in a direction orthogonal to the longitudinal direction of the test piece TP. The light emitting element 9 and the light receiving element 8 constitute a sensor for detecting the test piece TP. If the light from the light emitting element 9 is not blocked and the light receiving element 8 is receiving light, a message indicating that the test start is not permitted is displayed on a monitor or the like. In addition, as a detection sensor of the test piece TP,
A sensor that detects reflected light of light applied to the test piece TP may be used, or a mechanical limit switch may be used. In the present embodiment, the light emitting element 9 and the light receiving element 8 are provided on the upper end surface of the gripping tooth 1. A light receiving element may be provided.

Next, the operation of the material testing machine shown in FIGS. 1 and 2 will be described. First, before mounting the test piece TP, the pair of gripping teeth 3 are opened so that the test piece TP can be inserted between the gripping teeth 3. Then, the test piece TP is inserted from the lower end side of the gripping teeth 3 and lifted while holding the test piece TP along the load axis, and the drive shaft is rotated by rotating the drive shaft while maintaining the test piece TP at a predetermined position. Twin grip teeth 3
Is closed and the test piece TP is gripped. In addition, the test piece TP is similarly gripped by the lower gripping teeth not shown.

After the test piece TP is mounted on the material testing machine, the load is applied to the test piece TP by, for example, raising the crosshead 1. Check the gripping status on a monitor or the like.
That is, along the load axis, the test piece TP is
If the light is not gripped from end to end, the light emitted from the light emitting element 9 is not blocked, and a message indicating that the test cannot be started is displayed on the monitor based on the light detection state of the light receiving element 8. Further, when the test piece TP is not detected by the sensor, the driving of the crosshead 1 is forcibly forced to O.
A switch for performing FF may be provided so that a load on the test piece TP cannot be applied. Then, when the test piece TP is not normally gripped, the drive shaft is reversed, the gripping teeth 3 are opened to open the test piece TP, and then the test piece TP is gripped again. Thereafter, the test is started again after confirming that the test start permission is displayed on the monitor again.

In addition, it is possible to determine whether or not to grip the test piece TP based on the detection status of the detection sensor of the test piece TP. That is, in the case of a mechanism in which the drive shaft that opens and closes the gripping teeth 3 is rotated by a drive motor, when a sensor does not detect the test piece TP, a switch for forcibly turning off the drive of the drive motor is provided to provide a test piece TP. May not be held when the test piece TP is not at the predetermined position.

That is, the following aspects are also included as modifications of the present invention.

(1) In a material testing machine provided with a pair of gripping teeth inside a crosshead, it is detected that a test piece has reached an end of the pair of gripping teeth along a load axis. A material testing machine comprising: a sensor at this end; and means for preventing movement of the crosshead so as not to apply a load to the test piece when the test piece is not detected by the sensor.

(2) In a material testing machine provided with a pair of gripping teeth inside the crosshead, it is detected that the test piece has reached the end of the pair of gripping teeth along the load axis. A material testing machine comprising a sensor at this end and means for preventing the pair of gripping teeth from being closed so as not to grip the test piece when the test piece is not detected by the sensor. .

[0017]

As described above, according to the present invention,
Even if the gripping teeth are inside the crosshead and the actual gripping state of the test piece is unknown, the test piece must be gripped by effectively using the predetermined range of the gripping surface of the gripping tooth. That is, since it can be confirmed that the test piece reaches the end of the gripping tooth along the load axis, chuck slip of the test piece is reduced. Further, the gripping force is not concentrated on a part of the test piece, and the occurrence of the chuck breakage of the test piece is reduced. Further, the gripping surface of the gripping teeth no longer acts on the gripping force locally, and wear and damage are reduced, and the durability of the gripping teeth is significantly improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration near a crosshead in a material testing machine according to the present invention.

FIG. 2 is a cross-sectional view of the vicinity of the crosshead viewed from the AA direction in FIG.

FIG. 3 is a diagram showing a schematic configuration of a conventional gripping tooth opening / closing mechanism.

[Explanation of symbols]

 1 ··· Cross head 3 ··· Gripping teeth 4 ··· Holder 8 ··· Light receiving element 9 ··· Light emitting element

Claims (1)

[Claims] 1. A material testing machine having a pair of gripping teeth inside a crosshead, wherein a sensor for detecting a gripping state of the test piece by the pair of gripping teeth is arranged near the pair of gripping teeth. Material testing machine characterized by the following.