JP2000314690A - Gripper device for plywood - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gripper device for plywood capable of applying always accurate tensile load to a test piece without allowing eccentric load to act on the test piece even if the test piece of plywood of which the part to be tested is not present on the center in the thickness direction of the plywood is gripped by simple operation. SOLUTION: The mutually parallelly extending guide plates 3a, 3b on the side of one gripper 1 among a pair of grippers 1, 2 are fixed to the other gripper 2 and a plurality of rollers (rolling bearings) 41-48 coming into rolling contact with the guide plates 3a, 3b are supported on the gripper 1 in a freely revolvable manner. By this constitution, even if the eccentric force caused by the form of a test piece T acts on the gripper 1 or 2 when the grippers 1, 2 approach each other/separate from each other, the movement of the gripper 1 or 2 by the eccentric force is prevented by the presence of the rollers 41-48 being in rolling contact with the guide plates 3a, 3b and no eccentric load acts on the test piece T.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gripping device for gripping both ends of a plywood for performing a tensile test or the like.

[0002]

2. Description of the Related Art In an adhesive strength test of a wood plywood by a shearing method, as shown in a perspective view of FIG. By injecting, the intensity measurement target portion Tt
Only the both ends of the test piece T are connected by only the both ends, and the both ends of the test piece T are respectively gripped by grips to apply a tensile load (for example, JIS W1101, ASTM)
D906). In this test, the measurement target portion Tt of the strength may not be located on the thickness center line of the test piece T as illustrated.

Conventionally, a gripping device used for such a test is, as shown in a front view in FIG.
1 and the lower grip 52 are opposed to each other, and parallel guide plates 53a and 53b extending toward the upper grip 51 are fixed to both side surfaces of the lower grip 52, respectively, and the respective guide plates 53a, 53b and the upper grip are fixed. Tool 51
A structure in which a slight gap G is provided between both side surfaces of the lens is adopted. In this gripper device, each gripper 5
1, 52 are gripping teeth 511a, 511b, 521a, 5 for gripping the test piece T by approaching / separating from each other on the gripper bodies 510, 520, respectively.
21b, each gripping tooth 511a, 5
11b, and 521a and 521b are the gripper body 51.
It can be moved individually by bolts B screwed into 0,520. Each of the bolts B of the upper grip 51 passes through a slit-shaped notch S formed in each of the guide plates 53a and 53b so that its head reaches the outside.

[0004] Guide plates 53a and 53b respectively hold both ends of a test piece T as shown in FIG.
When a tensile load is applied to the test piece T by gripping the lower grip 52 and moving the upper grip 51 upward, for example, in a state of being gripped at the center of the 52 (the center in the opening and closing direction of each gripping tooth), This is for preventing the gripper 51 from being displaced in the left-right direction in the figure.

That is, when the test piece T is gripped at the center of the upper and lower grips 51, 52, and the grips 51, 52 are separated from each other to apply a tensile load to the test piece T, the load center C
Is located on the center of the thickness of the test piece T, but when a load is applied to the test piece T having the test portion Tt deviating from the center of the thickness as shown in FIG. Test target portion T that connects upper and lower grips of test piece T
Since t deviates, the eccentric force acts on the upper gripping tool 51 and shifts in the left-right direction in FIG. 5. As a result, an eccentric load acts on the test piece T, so that an accurate tensile load cannot be applied. Therefore, the guide plates 5 are provided on both left and right sides of the upper grip 51.
When the upper grip 51 is displaced in the left-right direction due to the eccentric force acting on the upper grip 51, the upper grip 51 is brought into contact with one of the guide plates 53a, 53b by providing the upper grip 51 with the guide plate 53a. Or, it moves upward along 53b to prevent the displacement in the left-right direction.

[0006]

According to the above-described conventional plywood gripping device, when the test piece T as shown in FIG. 4 is tested, the upper grip 51 is moved to the left and right guide plates 53a, 53b. Although the displacement in the left-right direction is suppressed by being guided by the guide, the gap G exists between the side surface of the upper grip 51 and the guide plates 53a and 53b. There is a problem that the gripper 51 shifts in the left-right direction, and an eccentric load acts on the test piece W, so that a tensile load cannot be applied accurately.

Here, when the test of the test piece T illustrated in FIG. 4 is performed by the conventional gripping device illustrated in FIG. 5, the upper and lower gripping members 51 are set so that the test target portion Tt and the load center C coincide with each other. , 52, or the test piece T and the upper and lower gripping teeth 511a so that the test target portion Tt and the load center C also coincide, as shown in FIG. By interposing the spacer 54 between the test piece T and 521a, it is possible to prevent the eccentric load from acting on the test piece T. However, in any case, the operability of the gripping work is inferior and the work efficiency is reduced. is there.

The present invention has been made in view of such circumstances, and even if the test object portion Tt shown in FIG. 4 is a plywood test piece T deviating from the center of thickness, it can be easily operated. An object of the present invention is to provide a gripping device for plywood that can always apply an accurate tensile load without being subjected to an eccentric load.

[0009]

In order to achieve the above-mentioned object, a gripping device for plywood according to the present invention comprises a pair of gripping tools each having openable / closable gripping teeth for gripping an end of a test piece. However, in a plywood gripping device which is disposed so as to be able to approach / separate from each other, a gripping device for one of a pair of gripping devices is provided with a predetermined interval in a gripping direction of the test piece by the gripping device. A pair of guide plates extending in parallel to the other gripping tool are fixed, and the other gripping tool has at least two rollers that are in rolling contact with the respective guide plates. It is characterized by being rotatably supported at predetermined intervals in the longitudinal direction.

According to the present invention, a plurality of rollers rotatably supported by the other gripping member are brought into rolling contact with a pair of guide plates fixed to one of the grippers, so that a gap between the guide plate and the rollers is increased. It is an object of the present invention to eliminate the need for intervening a gap in the device and achieve the intended purpose.

That is, in the present invention, a roller rotatably supported on the other gripper side is provided on each guide plate with respect to a pair of guide plates fixed to one gripper and extending on the other gripper side. On the other hand, at least two rolling contacts are made at predetermined intervals in the longitudinal direction. Accordingly, when the pair of grips are moved toward / away from each other, each gripper relatively moves while at least two rollers each contact each guide plate without a gap, and each gripping tooth is moved. Will not move in the gripping direction of the test piece. Therefore, even if the test portion Tt shown in FIG. 4 is a test piece deviating from the center of thickness, an eccentric load is not applied to the test piece, and an accurate test can always be performed. At the same time, there is no need to use a spacer as shown in FIG. 6 or adjust the gripping position in the thickness direction of the test piece by individually moving the gripping teeth of each gripping tool. As the gripping teeth, it is possible to select the type that is commonly used for ordinary gripping tools that move in the opposite direction in synchronization with each other with the center in the gripping direction sandwiched. Operability can also be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA of FIG.
Is a BB sectional view of the same.

The upper gripper 1 and the lower gripper 2 facing each other include a gripper body 10 and 20, respectively, and a pair of gripping teeth supported slidably and displaceably with respect to the gripper bodies 10 and 20, respectively. 11a, 11b, 21a, 21b
And gripper holding parts 12a, 12b for holding the gripping teeth 11a, 11b, 21a, 21b against the gripper bodies 10, 20 in a direction perpendicular to the paper surface.
22a, 22b and each gripping tooth 11a, 11b, 21
Opening / closing mechanisms 13 and 23 for opening and closing a and 21b are main components. On the upper surface of the gripper main body 10 of the upper gripper 1, for example, a connection portion 14 for connecting to a universal joint mounted on a crosshead of a material testing machine, and a gripper body 20 of the lower gripper 2. Are provided on the lower surface thereof for connection to a universal joint similarly mounted on the table of the material testing machine.

Each of the gripper bodies 10 and 20 is formed with a wedge surface W which becomes narrower on the mating side, and each of the pair of gripping teeth 11a and 11b and 21a and 21b slides on the wedge surface W. By contact, they approach / separate in synchronization with each other.

That is, the opening and closing mechanisms 13 and 23 are connected to the horizontal fulcrum pins 13 attached to the gripper bodies 10 and 20.
a, 23a, operating levers 13b, 23b one end of which is rotatably supported by the fulcrum pins 13a, 23a, and brackets 13c, 13d, 23c fixed to the respective gripping teeth 11a, 11b, 21a, 21b. , 23d
And between the respective brackets 13c and 13d, and 23c
Pins 13e and 23e inserted between the pins 13e and 23d so as to be rotatable and slidable in the axial direction, respectively.
3e has one end rotatably supported and the other end has an operation lever 1
Links 13f, 2 pin-joined to 3b, 23b
3f. In this configuration, by operating the operation levers 13b, 23b in the direction of arrow D shown in FIG. 2, each of the gripping teeth 11a, 11b, 21a, 2
1b moves up and down along the wedge surface W, and the gripping teeth 11a and 11b and 21a and 21b approach / separate, respectively, depending on the inclination angle of the wedge surface W. Therefore,
By operating the operation levers 13b and 23b, the gripping teeth 11a and 11b, and 21a and 21b can move in opposite directions with respect to their respective center lines, and can always hold the test piece T on the center lines. .

The gripper body 20 of the lower gripper 2 will now be described.
Guide plates 3a and 3b are fixed to both side surfaces of the upper grip 1, respectively, and the guide plates 3a and 3b extend upward in parallel with each other.
0 is opposed to both side surfaces of the “0” through a slight gap.
On the other hand, on both sides of the gripper body 10 of the upper gripper 1, two in the thickness direction near the upper and lower ends, respectively.
That is, a total of four rolling bearings 41 to 48 (4
2, 46 are not shown), but are each supported rotatably about a horizontal axis. Each of these rolling bearings 41 to 48 has an outer peripheral surface of an outer ring of the guide plate 3.
Rolling contacts a and 3b with a gap of 0 or a slight negative gap.

According to the above embodiment of the present invention, for example, when a test of a plywood test piece T as shown in FIG. 4 is performed, both ends of the test piece T are gripped by the upper and lower jaws 1 and 2. However, in gripping, each operation lever 13b,
By operating 23b, the upper and lower ends are gripped at the centers of the gripping teeth 11a and 11b and the centers of the gripping teeth 21a and 21b, respectively. In this state, when the cross head of the material testing machine is driven to separate the upper grip 1 from the lower grip to apply a tensile load to the test piece T, the center of the load is the test target portion Tt of the test piece T. Therefore, the eccentric force acts on the upper grip 1 so that the upper grip 1 is shifted in either the left or right direction.
To 48 are in rolling contact with the left and right guide plates 3a and 3b without any gap, so that the movement to the left and right is prevented, and the upper grip 1 moves only in the moving direction of the crosshead, that is, in the load direction. Therefore, an eccentric load does not act on the test piece T, and an accurate test can be performed.

During the test, each of the rolling bearings 41 to 48 of the upper grip 1 is attached to the guide plate 3a or 3b.
, But there is no frictional resistance due to the rolling contact, and there is no particular effect on the test.

In the above embodiment, the guide plates 3a and 3b are fixed to the lower grip 2 and the rolling bearings 41 to 48 are supported on the upper grip 1, but the upper grip is used. Even when adopting a configuration in which the guide plates 3a and 3b are fixed to one side and the rolling bearings 41 to 48 are supported on the lower grip 2 side, the same operation and effect as described above can be achieved.

In the above-described embodiment, the rolling bearings 41 to 41 are used as members that make rolling contact with the left and right guide plates to prevent the upper grip 1 from moving in the left-right direction.
Although 48 is used, it is a matter of course that these may be rotatable rollers.

Further, according to the present invention, the lower grip 2 is fixed when a tensile load is applied as in the above embodiment.
It goes without saying that a use method of fixing the upper grip 1 and separating the lower grip 2 in addition to separating the upper grip 1 can be adopted.

[0022]

As described above, according to the present invention, the guide plates extending to the other side in parallel with each other at a predetermined interval in the gripping direction of the test piece are fixed to one side of the upper and lower grips. Since the other gripper has at least two rollers in rolling contact with each guide plate in the longitudinal direction for each guide plate, both ends of the test piece are gripped by the upper and lower grippers. When a tensile load is applied to a test piece by separating one of them from the other, even if the load center and the test target portion of the test piece are shifted and an eccentric force acts on the gripper on the moving side, The movement of the gripping tool due to the eccentric force is prevented by the rolling contact of the roller with the guide plate, so that an eccentric load does not act on the test piece, and an accurate test can always be performed. At the same time, since the eccentric load does not act on the test piece due to the adoption of such a configuration, even if the plywood does not have the portion to be tested at the center position in the thickness direction, the plywood can be used without taking measures such as using a spacer. It is possible to employ a center-grip type gripper in which the gripping teeth move synchronously, thereby facilitating a gripping operation of a test piece in a plywood adhesive strength test or the like.

[Brief description of the drawings]

FIG. 1 is a front view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along the line BB of FIG. 1;

FIG. 4 is a perspective view showing a form example of a test piece used for an adhesion test of plywood.

5 is a front view showing an example of a conventional plywood gripping device for gripping the test piece T shown in FIG.

FIG. 6 is a diagram illustrating a load center and a test target portion Tt when gripping the test piece T of FIG. 4 using a conventional plywood gripping device.
FIG. 9 is an explanatory diagram of an example of a countermeasure for matching.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper gripping tool 2 Lower gripping tool 10, 20 Gripping tool main body 11a, 11b, 21a, 21b Gripping tooth 13, 23 Opening / closing mechanism 3a, 3b Guide plate 41-48 Rolling bearing T Test piece Tt Test target portion

Claims (1)

[Claims] 1. A plywood gripping device in which a pair of grippers each having openable and closable gripping teeth for gripping an end portion of a test piece are opposed to each other so as to approach / separate from each other. A pair of guide plates extending to the other gripper side in parallel with each other at a predetermined interval in the gripping direction of the test piece by the gripper is fixed to one of the grippers, and The gripper is characterized in that at least two rollers each in rolling contact with each guide plate are rotatably supported at a predetermined interval in the longitudinal direction of each guide plate. Gripper device for plywood.