JPH0562845U - Material testing machine - Google Patents

Abstract

(57) [Summary] (Corrected) [Purpose] Having a gripper that does not apply an initial load when gripping a test piece and that can give a greater tightening force than the conventional wedge-positioning gripper. Provide a material testing machine. [Composition] Between the slopes 71c and 71d of the wedge teeth 71 of the wedge positioning type grip and the slope of the grip body 72,
By providing a plurality of rollers R ... R and a retainer 74 for holding them, respectively, and providing a mechanism for moving the retainer 74 or the grip body 72 up and down, the test piece can be efficiently produced under the wedge effect of rolling contact. Get the tightening force of.

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material testing machine capable of applying at least a tensile load to a test piece while holding both ends of the test piece.

[0002]

2. Description of the Related Art When performing a tensile test on a test piece, generally, both ends of the test piece are grasped by grasping tools, and a force is applied in a direction in which both grasping tools are relatively separated by a load mechanism. Conventionally, there has been a wedge tooth localization type gripping tool.

As shown in the central longitudinal cross-sectional view of FIG. 5, the wedge positioning type gripping device is configured by a wedge tooth 51, a gripping body 52, and a vertical movement mechanism 53 of the gripping body 52. Has been done.

The wedge tooth 51 is composed of a pair of blocks 51a and 51b arranged so that the gripping tooth surfaces T for gripping the test piece face each other, and the back surface of the gripping tooth surface T of each of the blocks 51a and 51b. Are formed by inclined surfaces 51c and 51d that approach each other at an angle α. The blocks 51a and 51b can be displaced in the directions in which the respective tooth flanks T, T approach and separate from each other.

The grip body 52 is formed with a taper groove 52 a that encloses the wedge tooth 51 inside, and both inner surfaces of the taper groove 52 a face the slopes 51 c and 51 d of the wedge tooth 51. And is formed by inclined surfaces 52b and 52c that are respectively inclined at the same angle α.

The vertical movement mechanism 53 is composed of a screw 53a fixed to the tester and a nut 53c screwed into the screw 53a and rotated by a handle 53b. The nut 53c has a grip body. There is formed a groove 53d into which the protrusion 52d formed on the upper end portion of 52 is fitted, and the nut 53c can be moved up and down along the screw 53a by rotating this so that the grip body 52 can be moved up and down. It is composed of

In such a structure, when the nut 53c is rotated to move the grip body 52 upward, the wedge effect based on the contact between the slopes 51c and 52b and 51d and 52c causes both of the wedge teeth 51 to move. The gripping tooth surfaces T, T approach each other and tighten the test piece. At this time, since the wedge tooth 51 does not move up and down, no initial load is applied to the test piece, which is the reason why it is referred to as the "wedge tooth localization method".

Further, according to such a structure, when a tensile load is applied while the test piece is gripped, a downward force (toward the tip side) is applied to the wedge tooth 51, so that a so-called automatic tightening force acts during the test. There is also an advantage.

[0009]

By the way, in the pinching operation of the test piece in the wedge tooth localization type gripping tool as described above, the manual torque T applied to the handle 53b is applied to the screw by the wedge effect of the angle α. 53a and nut 53c are used to convert the upward movement force V of the grip body 52 into the tightening force F ₃ of the test piece. The efficiency at the time of conversion is the slopes 51c and 52b, and It is affected by the coefficient of friction between 51d and 52c. Here, since this friction is sliding friction, the value of the friction coefficient is large, and therefore the loss is large. As a result, the tightening force F ₃ becomes smaller, and for the same reason, the above-mentioned automatic tightening force does not become so large, and a so-called “chuck slip” phenomenon occurs during the test, and there is a problem that an accurate test may not be possible. .

The present invention has been made in view of such a point, and like the conventional wedge tooth positioning type gripping tool, an initial load is not applied to the test piece and a large tightening force can be obtained. The purpose is to provide a material testing machine equipped with a grip.

[0011]

[Means for Solving the Problems] To achieve the above object, the material testing machine of the present invention has a gripping tooth for gripping a test piece as shown in FIG. It is composed of a pair of blocks 71a and 71b which are arranged so that the surfaces T face each other, and the rear surfaces of the respective gripping tooth surfaces T are close to each other at the tip end side and which can be moved toward and away from each other. A wedge-shaped tooth 71, a grip body 72 in which two inner wall surfaces 72b and 72c facing each other are formed on the outer sides of both slopes 71c and 71d of the wedge tooth 71, and the wedge tooth 71. A plurality of rollers R..R arranged between the slopes 71c, 71d of the and the wall surfaces 72b, 72c of the grip body 72, and a retainer 74 for connecting and holding the plurality of rollers R..R. , A pair of gripping tools 7 and 8 configured by a vertical movement mechanism 73 for vertically moving either the cage 74 or the gripping tool main body 72 with respect to the wedge teeth 71 (see FIG. 1). ) Is characterized by.

[0012]

[Operation] When the rollers R, ... R arranged between the inclined surface 1c and the wall surface 2b and between 1d and 2c are moved upward (FIG. 3) or the grip body 2 is moved upward (FIG. 2) By the wedge effect, a force for approaching each other acts on both blocks 1a and 1b of the wedge tooth 1. At this time, since the rollers R ... R intervene between the wedge teeth 1 and the grip body 2 and the contact therebetween is rolling contact, the upward moving force V to the tightening force F ₁ Alternatively, the conversion efficiency to F ₂ can be improved by the difference between the sliding friction coefficient and the sliding friction coefficient as compared with the conventional wedge orientation type gripping tool, and the intended purpose can be achieved.

[0013]

Embodiment FIG. 1 is a front view showing the overall configuration of an embodiment of the present invention. Lower ends of a pair of left and right screw rods 2, 2 are rotatably supported on the table 1, and upper ends of the screw rods 2, 2 are supported by a yoke 3.

Nuts 4 a, 4 a are fixed to both ends of the crosshead 4, and the nuts 4 a, 4 a are screwed into the left and right screw rods 2, 2. Each of the screw rods 2 and 2 is adapted to be synchronously rotated by a servomotor, a deceleration and a transmission mechanism disposed in the table 1, and the rotation of the screw rods 2 and 2 causes the crosshead to rotate. 4 is configured to move up and down.

A load cell 5 is arranged on the crosshead 4, and an upper grip 7 is provided on a sensitive portion of the load cell 5 via a universal joint 6, and a lower grip 8 is provided on the upper surface of the table 1. The tensile test piece TP is held between the upper and lower grips 7 and 8.

FIG. 2 is a central longitudinal sectional view showing the structure of the upper grip 7. In this example, the gripper 7 includes a wedge tooth 71, a gripper body 72, a vertical movement mechanism 73 of the gripper body 72, a plurality of rollers R, ... R interposed between the wedge tooth 71 and the gripper body 72, and each. It is composed of a holder 74 for holding the rollers R.

The wedge tooth 71 is substantially the same as a conventional wedge tooth positioning type gripping tool, and is constituted by a pair of blocks 71 a and 71 b arranged so that gripping tooth surfaces T for gripping a test piece face each other. The rear surface of the gripping tooth surface T of each of the blocks 71a and 71b is formed by inclined surfaces 71c and 71d which approach downwardly at an angle α with respect to the vertical line. The blocks 71a and 71b can be displaced in a direction in which the tooth surfaces T 1 and T 2 approach and separate from each other.

The grip body 72 is formed with a taper groove 72 a that encloses the wedge tooth 71 inside, and the left and right inner wall surfaces 72 b and 72 c of the taper groove 72 a are formed on the inclined surfaces 71 c of the wedge tooth 71. And 71d, respectively, and are inclined at the same angle α.

A plurality of rollers R ... R having the same outer diameter dimension are inserted between the inner wall surface 72b of the grip body 72, the slope 71c of the wedge tooth 71, and 72c and 71d. There is. The rollers R, ... R inserted between the respective surfaces are held by a retainer 74 so as to be rotatable about their respective rotation centers.

The up-and-down moving mechanism 73 also has a structure similar to that of a conventional wedge-positioning type grip, and includes a screw 73a fixed to the tester side, a screw 73a screwed into the screw 73a, and a handle. The nut 73c is formed by a nut 73c which is rotated by 73b. The nut 73c is formed with a groove 73d into which a protrusion 72d formed on the upper end of the grip body 72 is fitted. The grip body 72 can be moved up and down along with 73a. Note that a fixed position 73e is formed at the tip of the screw 73a to prevent the wedge tooth 71 from moving upward.

The structure of the lower gripping tool 8 is exactly the same as that of the upper gripping tool 7 described above except that the gripping tool 8 is turned upside down. In the above-described embodiment of the present invention, when the nut 73c is rotated to move the grip body 72 upward, the wedge effect of the angle α causes the two blocks 71a and 71b of the wedge teeth 71 to approach each other and the respective grip teeth 72c. The test piece TP is tightened by the surfaces T, T. At this time, since the rotatable rollers R, ... R are interposed between the inclined surface 71c and the inner wall surface 72b, and between 71d and 72c, The frictional force acting on each of the surfaces 71c and 72b and 71d and 72c is based on the rolling friction coefficient.

The relationship between the upward moving force V of the grip body 72 and the force N ₁ acting on the slopes 71c and 71d of the blocks 71a and 71b of the wedge teeth 71 at right angles is as shown in the equation (1). Therefore, the relationship between the tightening force 2F and the transfer force V of the test piece TP by the gripping tooth surfaces T, T is as shown in the equation (2).

[0023]

[Equation 1] In each of these equations, μ is a rolling friction coefficient, and in the conventional wedge localization type grip, when the wedge angle is the same α, this rolling friction coefficient μ becomes a sliding friction coefficient μ ′. Since μ <μ ', the above-described embodiment of the present invention uses the upward moving force V 1 of the grip body 72, and hence the torque applied to the handle 73b, as compared with the case of using the conventional wedge positioning type grip. Even if they are the same, the tightening force is improved by the difference between the rolling friction coefficient μ and the sliding friction coefficient μ ′. This means that the automatic tightening force when a tensile load is applied to the test piece W is also larger than in the conventional case, and the chuck slip phenomenon is less likely to occur.

FIG. 3 is a central longitudinal sectional view of a gripping tool according to another embodiment of the present invention, and FIG. 4 is an ABCD sectional view thereof. This embodiment is different from the embodiment described above in that the rollers R ... R inserted between the inclined surfaces 71a and 71b of the wedge teeth 71 and the inner wall surfaces 72b and 72c of the grip body 72 are located at the tips of the grips. The point is that the diameter becomes larger as it goes, and the vertical mechanism 73 is configured to vertically move the rollers R ,.

That is, in this example, if the angle of each slope of the wedge tooth 71 with respect to the vertical line is α, the angles of the inner wall surfaces 72b, 72c of the groove 72a of the grip body 72 are β (<α), respectively. The diameters of the rollers R, ... R interposed between the respective surfaces are such that all the rollers R ,. That is, while being held by the retainer 74, the rollers R..R are in contact with both surfaces facing each other at an angle .gamma. (= .Alpha .-. Beta.).

The vertical movement mechanism 73 is composed of a screw 73a fixed to the testing machine side and a nut 73c screwed into the screw 73a and rotated by a handle 73b as in the above-described example. However, the projection 73a formed on the upper end of the retainer 74 is fitted in the groove 73d formed in the nut 73c, and the nut 73c moves up and down along the screw 73a by turning the nut 73c. , All the rollers R ... R can be moved up and down via the cage 74.

In this example, since the grip body 72 is not moved up and down, a proper jig (not shown) is attached to a fixed portion such as a fixed position 73e formed at the tip of the screw 73a of the up-and-down moving mechanism 73. Fixed through.

In this example, when the handle 73b is rotated and moved upward, the rollers R, ... R move upward via the retainer 74, and the wedge tooth 71 causes the wedge effect. The two blocks 71a, 71b come close to each other to generate the tightening force F ₂ of the test piece TP, and this tightening force F ₂ is as shown in the following formula (3).

[0029]

[Equation 2] As is clear from this formula, the tightening force F ₂ in this example is μ <1 when the inclination angle α of the wedge teeth 71 is the same as in the previous example and the torque applied to the handle 73b is the same. ₂ > F ₁ and the tightening force can be improved more effectively.

[0030]

As described above, according to the present invention, the retainer is provided between the slope of the back surface of the wedge tooth composed of the pair of blocks and the inner wall surface of the grip body containing the wedge tooth. Since there is a plurality of rollers that are rotatably held by the interlocking mechanism and a mechanism that moves the grip body or the retainer vertically with respect to the wedge teeth is provided, Material with wedge-positioning type grip As with the tester, the desired load is not applied to the test piece when the test piece is tightened, and the wedge surface is different from the conventional wedge-positioning type grip when tightening. Since rolling contact is made instead of sliding contact, the efficiency of force conversion during tightening is greatly improved, and a large tightening force can be obtained with a small amount of force, and a tensile load is applied to the test piece. The automatic tightening force when it is pulled is also increased, and problems such as the chuck slip phenomenon do not occur.

[Brief description of drawings]

FIG. 1 is a partial sectional front view showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a central vertical cross-sectional view showing the structure of the grip 7 above it.

FIG. 3 is a central longitudinal sectional view showing the structure of an upper grip according to another embodiment of the present invention.

4 is an ABCD cross-sectional view of FIG.

FIG. 5 is a central longitudinal cross-sectional view showing a structural example of a conventional wedge positioning type grip.

[Explanation of symbols]

 1 ... ・ Table 2 ・ ・ ・ ・ Screw rod 3 ・ ・ ・ ・ ・ ・ Yoke 4 ・ ・ ・ ・ Crosshead 5 ・ ・ ・ ・ Load cell 7 ・ ・ ・ ・ Upper grip 71 ・ ・ ・ ・ Wedge 71a, 71b ... Blocks 71c, 71d ... Slope T ... Gripping teeth 72 ... Gripping tool main body 72a ... Grooves 72b, 72c ... Inner wall surface 72d ... 72e ... ・ Per fixed position 73 ・ ・ ・ ・ Vertical movement mechanism 73a ・ ・ ・ ・ Screw 73b ・ ・ ・ ・ Handle 73c ・ ・ ・ ・ Nut 73d ・ ・ ・ ・ Groove 74 ・ ・ ・ ・ Cage 74a ・ ・..Protrusions R ... R ... Roller 8 ... Lower grip

Claims (1)

[Scope of utility model registration request] 1. A material testing machine comprising a pair of grips for gripping both ends of a test piece, and a load mechanism for applying a tensile load to the test piece gripped by both grips, wherein each of the grips is tested. The gripping tooth surfaces for gripping the pieces are arranged so as to face each other, and each of the gripping tooth surfaces is formed of a pair of blocks which can be moved toward and away from each other and are formed by inclined surfaces such that the back surfaces of the gripping tooth surfaces approach each other on the tip side. A wedge-shaped wedge tooth as opposed to the outside of the above-mentioned both slopes of the wedge tooth.
Grip body having two wall surfaces, a plurality of rollers arranged between each slope of the wedge tooth and each wall surface of the grip body, a retainer for connecting and holding the plurality of rollers, and the retainer. Alternatively, a material testing machine characterized in that it is configured by an up-and-down moving mechanism that moves one of the gripping tool bodies up and down with respect to the wedge teeth.