JP3208871B2 - Material testing machine - Google Patents

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 having a universal joint.

[0002]

2. Description of the Related Art A table to which a lower grip is attached and a crosshead to which an upper grip is attached are provided. For example, the crosshead is raised with respect to the table, and a tensile load is applied to a test piece gripped by both grips. Is known. For example, Japanese Patent Application Laid-Open No. 2-2
No. 03241 discloses a material testing machine in which the crosshead and the upper grip are connected via a universal joint consisting of a ball seat and a ball seat receiver. If a universal joint is used in this way, even if the axes of the upper and lower grips are misaligned,
When loading, the upper grip will tilt according to the deviation,
No eccentric load is applied to the test piece.

[0003]

However, in the universal joint composed of the ball seat and the ball seat surface as described above, the sliding friction force acts because the contact area between the ball seat and the ball seat surface is large.
If the amount of axis deviation of the upper and lower grips is large, the eccentric load cannot be sufficiently removed in some cases.

An object of the present invention is to provide a material testing machine provided with a universal joint capable of completely removing an eccentric load even if the amount of axial deviation of a vertical grip is large by reducing sliding frictional force. .

[0005]

SUMMARY OF THE INVENTION The present invention is applied to a material testing machine for gripping and loading a test piece with a pair of upper and lower grips provided detachably from each other via a universal joint, and The above object is to provide a support means for elastically supporting the lower gripper on the lower universal joint,
This is achieved by providing a bearing that supports the lower gripper and that allows the axis of the inner ring to tilt relative to the outer ring.

[0006]

The bearing pivotally supports the lower grip so that the axis of the lower grip can be relatively tilted. The bearing means resiliently supports the lower grip and reduces the rate at which its own weight acts on the bearing, resulting in smooth operation of the bearing.

[0007]

FIG. 4 is a view showing one embodiment of a material testing machine according to the present invention, and is a schematic front view showing the entire structure thereof. In FIG. 4, a table 2 is held at a lower portion between a pair of columns 1, and a cross yoke 3 is suspended on an upper portion. Reference numeral 4 denotes a crosshead whose both ends are screwed to a screw rod inside the column 1, and the crosshead 4 moves up and down with respect to the table 2 by rotation of the screw rod. A lower grip 6 is connected to an upper portion of the table 2 via a universal joint 10 and a fixed rod 5, and an upper grip is mounted to a lower surface of the crosshead 4 via a load cell 7, a universal joint 20 and a load rod 8. A tool 9 is coaxially connected to the lower grip 6. The test piece TP is gripped by these two gripping tools 6 and 9.

FIG. 1 is a sectional view showing a lower universal joint 10. In FIG. 1, reference numeral 11 denotes a bearing holder fixed to the table 2 via bolts 12. As shown in FIGS. 2 and 3, the bearing holder 11 has a disk-shaped flange portion 11b that protrudes inward at an upper end opening of a cylindrical main body 11a, and is spaced apart in the circumferential direction of the main body 11a. And a bolt hole 11c is formed. In the bearing holder 11, the outer ring 13b is
A thrust self-aligning roller bearing 13 is housed in a state in which it is in contact with the lower surface of 1b, and a fixed rod mounting member 18 is supported and held via the bearing 13.

The thrust self-aligning roller bearing 13 has an annular inner ring 13a and an outer ring 13b which can be separated from each other, and the outer ring 13b is formed by a substantially frusto-conical roller 13c rotatably supported on the inner ring 13a side. 13a is rotatably supported with respect to the rotation. More specifically, Roller 1
3c is formed so that its central portion is slightly outwardly swollen, and the axis of the inner ring 13a is tiltable relative to the axis of the outer ring 13b over the entire circumference. Thus, the fixed rod 5 can be tilted in any direction within 360 °, and the bearing 13 functions as a universal joint.

The fixed rod mounting member 18 has an upper portion 18a formed in a flange shape and a lower portion 18b formed in a stepped round bar shape.
The fixed rod 5 is attached to the upper part 18a. The inner ring 13a is tightly fitted to the small diameter round bar portion 18c, and its axial position is fixed by a nut 14 screwed to the lower end of the fixed rod mounting member 18 so that the inner ring 13a does not come off from the round bar portion 18c. I have. Also, fixed rod mounting member 1
The lock nut 15 screwed to the large-diameter round bar portion 18d of FIG. 8 engages with the upper surface of the bearing holder 11 so that the rod mounting member 18 does not fall down when it is set.

The lower end of the fixed rod mounting member 18 is formed with a recess 18e extending in the axial direction. The adjustment plate 16 is stored in the bearing holder 11 in a state of being placed on the table 2, and a spring 17 is interposed between the concave portion 18 e and the adjustment plate 16. The spring 17 applies an urging force to the fixed rod mounting member 18 to balance the own weight of the fixed rod mounting member 18 and its upper parts (the fixing rod 5, the gripper 6, the test piece TP, and the like), and applies the mounting member 18 thereto. Floating from table 2 and bearing 1
3 is operated smoothly, and the adjustment of the biasing force is performed by the thickness of the adjusting plate 16. Therefore, bearing 1
In order to minimize the contact pressure between the inner ring 13a and the outer ring 13b, when the fixed rod mounting member 18 is set, the screwing position of the lock nut 15 is set to such an extent that the lock nut 15 comes into loose contact with the upper surface of the bearing holder 11. . As the upper universal joint 20, a universal joint of a known type is used.

Next, the operation of the embodiment will be described. After appropriately adjusting the plate thickness of the adjusting plate 16 in consideration of the weight of the part above the fixed rod mounting member 18, the ends of the test piece TP are applied to the upper and lower grips 6, 9 with the lock nut 15 loosened. Let it be gripped. Gravity acts on the attachment member 18 and the nut 14 due to the weight of the attachment member 18 and the components above the attachment member 18, and a force acts in a direction in which the clamping force of the bearing 13 by the nut 14 is weakened. Applies a biasing force to the mounting member 18 to balance the weight of the mounting member 18 and its upper part.
The roller 13c and the outer ring 13b contact with an appropriate contact force and operate smoothly. Therefore, the upper and lower grips 6,
Even if the axis of 9 is displaced, the fixed rod 5 and, consequently, the lower grip 9 are inclined in accordance with the amount of displacement by the tilting of the inner ring 13a. Similarly, the upper grip 6 also tilts in accordance with the amount of displacement of the axis by the action of the upper universal joint 20.

Then, when the cross head 4 is raised by rotating the screw rod, the upper grip 9 rises with respect to the lower grip 6, and a tensile load is applied to the test piece TP. At this time, the tensile load acting on the fixed rod 5 is
8, the nut 14, the thrust spherical roller bearing 13 and the bearing holder 11 are transmitted to the table 2
The fixed rod 5 is securely supported, and the inner ring 13a of the bearing 13 tilts in the direction in which the tensile load acts, so that only the axial force acts on the fixed rod 5. Similarly, the upper gripper 6 is also tilted in accordance with the amount of displacement of the axis by the action of the upper universal joint 20.
Undesirable eccentric loads do not act on the test piece TP due to 0 and 20.

Therefore, according to this embodiment, the fixed rod 5 is pivotally supported by the thrust self-aligning roller bearing 13 so as to be tiltable, and the fixed rod 5 is floated by the spring 17 so that the bearing 13 always operates smoothly. So,
The sliding frictional resistance can be reduced as compared with the conventional case using a universal joint consisting of a ball seat and a ball seat surface, and the eccentric load on the test piece TP can be obtained even if the amount of axial deviation of the upper and lower grips 6, 9 is large. Can be completely removed, and in particular, the testing accuracy of brittle materials such as ceramics and composite materials can be improved.

In the correspondence between the embodiment described above and the claims, the spring 17 constitutes a bearing means, and the thrust self-aligning roller bearing 13 constitutes a bearing. The details of the material testing machine of the present invention are not limited to the above-described embodiment, and various modifications are possible. As an example,
In the above embodiment, the thrust self-aligning roller bearing is used. However, any bearing can be used as long as the axis of the inner ring can be tilted relative to the axis of the outer ring. If the tensile load is not large, a radial type bearing is also used. It is possible. Further, the fixed rod may be supported by the outer ring of the bearing, and the inner ring may be fixed to the table. Further, in one embodiment, the adjustment of the biasing force of the spring is performed by the thickness of the adjusting plate, but the biasing force may be externally adjusted by a screw or the like. The present invention is also applicable to a material testing machine of a type in which a test piece is loaded by moving a table while fixing a crosshead.

[0016]

As described above in detail, according to the present invention, the lower grip is pivotally supported by the bearing so as to be tiltable, and the lower grip is elastically supported by the support means to reduce its own weight. Since the ratio acting on the bearing is reduced, the sliding frictional resistance can be reduced compared to the conventional case where a universal joint consisting of a ball seat and a ball seat surface is used, and the amount of axial displacement of the upper and lower grips is reduced. The eccentric load on the test piece can be completely removed even if the value is large.

[Brief description of the drawings]

FIG. 1 is a view showing a material testing machine according to one embodiment of the present invention, and is a cross-sectional view showing a lower universal joint.

FIG. 2 is a perspective view of a bearing holder.

FIG. 3 is a sectional view taken along the line AA ′ of FIG. 2;

FIG. 4 is a schematic front view showing the overall configuration of a material testing machine according to one embodiment.

[Explanation of symbols]

 TP test piece 5 Fixed rod 6 Upper grip 9 Lower grip 10, 20 Universal joint 11 Bearing holder 13 Thrust self-aligning roller bearing 13a Inner ring 13b Outer ring 13c Roller 17 Spring 18 Fixed rod mounting member

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 3/00-3/62 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A material testing machine in which a test piece is gripped and loaded by a pair of upper and lower grips provided to be detachable from each other via a universal joint, wherein the lower universal joint comprises a lower grip. A material testing machine comprising: a bearing means for elastically supporting a tool; and a bearing for supporting the lower gripping tool and allowing an axis of an inner ring to tilt relative to an outer ring.