Material testing machine

When a crosshead descends after a specimen is loaded, pins attached to link members contact seat surfaces formed on seat members, and then contact side walls of the seat surfaces. As the crosshead descends further, the pins contacting the seat surfaces press the seat members 31. This pressing force moves a pair of first slide members away from each other as guided by a first rail, and moves a pair of second slide members away from each other as guided by a second rail 24. Consequently, tension loads in biaxial directions perpendicular to each other are applied to the specimen gripped by four chucks 25.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a material testing machine for testing specimens by applying thereto tensile forces in biaxial directions perpendicular to each other.

2. Description of the Prior Art

Such material test is also called a biaxial tensile test, which is conducted when measuring the strength of a metal plate, for example. Japanese Unexamined Patent Publication No. 2012-32218 discloses, as such a material testing machine, a biaxial tensile testing machine which includes a pair of specimen chucks movably arranged on each of two rails extending in directions perpendicular to each other.

FIG. 11is a perspective view showing a biaxial tension mechanism for applying testing forces to a specimen100in such conventional material testing machine.

The biaxial tension mechanism in this material testing machine includes a first rail91and a second rail92arranged on the surface of a base plate90to extend in directions perpendicular to each other. The first rail91has a pair of first moving members93slidably arranged thereon. These first moving members93, by being guided by the first rail91, are movable toward and away from each other along the first rail91. Each of these first moving members93has a chuck95for gripping the specimen100. On the other hand, the second rail92has a pair of second moving members94(only one of them appearing inFIG. 11) slidably arranged thereon. These second moving members94, by being guided by the second rail92, are movable toward and away from each other along the second rail92. Each of these second moving members94has a chuck96for gripping the specimen100. The base plate90which supports the first rail91and second rail92is disposed on a base block in a material testing machine body.

This biaxial tension mechanism includes a load member80connected to a crosshead in the material testing machine, for receiving a load applied from the crosshead. The pair of first moving members93are connected to the load member80by link members83each formed of a link81and a link82. The link81forming part of each link member83is rockably connected to the first moving member93by a pivot97. The link82forming part of each link member83is rockably connected to the load member80by a pivot85. The pair of second moving members94are connected to the load member80by link members84. One end of each link member84is rockably connected to the second moving member94by a pivot98. The other end of each link member84is rockably connected to the load member80by a pivot86.

With the biaxial tension mechanism in this material testing machine, when the load member80is pressed in a state of the specimen100gripped by the two pairs of chucks95and96, the pair of first moving members93are moved, by action of the link members83, away from each other along the first rail91, and the pair of second moving members94are moved, by action of the link members84, away from each other along the second rail92. Consequently, tension loads in the biaxial directions perpendicular to each other are applied to the specimen100gripped by the two pairs of chucks95and96.

As noted above, the biaxial tension mechanism of the material testing machine described in Japanese Unexamined Patent Publication No. 2012-32218 has a construction in which the pair of first moving members93and the load member80are connected by the link members83, and the pair of second moving members94and the load member80are connected by the link members84. With this construction, when placing the specimen100in a state gripped by the chucks95and96or detaching the specimen100, the operator needs to put in their hands through gaps between the link members83and84to carry out an attaching or detaching operation, which constitutes bad working efficiency. Particularly when a tool such as a spanner needs to be used in attaching or detaching the specimen100to/from the chucks95and96, there arises a problem of requiring a very long time for attaching or detaching the specimen100, which is due to interference between the tool and the link members83and84.

SUMMARY OF THE INVENTION

The object of this invention, therefore, is to provide a material testing machine which allows a specimen to be attached and detached easily to/from chucks, which material testing machine tests the specimen by applying thereto tensile forces in biaxial directions perpendicular to each other.

The above object is fulfilled, according to this invention, by a material testing machine comprising a pair of first moving members each having a chuck for gripping a specimen, the first moving members being movable toward and away from each other along a first axis by being guided by a guide member; a pair of second moving members each having a chuck for gripping the specimen, the second moving members being movable toward and away from each other along a second axis by being guided by a guide member; a load member for receiving a load applied by a loading mechanism; and four link members for connecting the pair of first moving members and the pair of second moving members to the load member, respectively; the load applied to the load member being transmitted through the four link members to the pair of first moving members and the pair of second moving members, thereby synchronously to move the pair of first moving members away from each other along the first axis, and to move the pair of second moving members away from each other along the second axis; wherein either the first moving members and the second moving members or the link members have seat surfaces formed thereon, while the other have contact portions formed thereon and shaped to correspond to the seat surfaces; and the seat surfaces and the contact portions are movable into contact with each other, respectively, thereby to connect the pair of first moving members and the pair of second moving members to the load member through the four link members.

According to such material testing machine, in the material testing machine which conducts a test by applying to a specimen tensile forces in biaxial directions perpendicular to each other, the seat surfaces and the contact portions are moved away from each other, whereby the unit having the chucks and the first and second moving members and the unit having the load member and link members can be separated easily. The specimen can therefore be easily attached to and detached from the chucks.

In one preferred embodiment, the contact portions comprise pins for contacting the seat surfaces, and each of the seat surfaces has an opening area formed in at least one of directions other than a direction of load transfer between the pin and the seat surface.

In another preferred embodiment, the seat surfaces are formed on the first moving members and the second moving members, while the pins are arranged on the link members.

According to such material testing machine, the first moving members and the second moving members can be moved by applying pressing forces between the pins and the seat surfaces. By moving the pins away from the seat surfaces through the opening areas formed around the seat surfaces, the unit having the chucks and the first and second moving members and the unit having the load member and link members can be separated easily. The specimen can therefore be easily attached to and detached from the chucks.

In a further preferred embodiment, the four link members are rockably attached to the load member connected to a crosshead, and the guide member for guiding the first moving members and the guide member for guiding the second moving members are fixed on a base portion disposed on a base block.

According to such material testing machine, tensile forces in the biaxial directions perpendicular to each other can be applied to the specimen by using the movement of the cross-head relative to the base block.

Other features and advantages of the invention will be apparent from the following detailed description of the embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of this invention will be described hereinafter with reference to the drawings.FIG. 1is a schematic view of a material testing machine according to this invention.

This material testing machine includes a base block11, a pair of right and left screw poles12erected on the base block11, and a crosshead13having nuts meshed with the right and left screw poles12and movable up and down relative to the screw poles12. The crosshead13has, attached thereto, an upper unit2of a biaxial tension mechanism1described hereinafter. The base block11has, attached thereto, a lower unit3of the biaxial tension mechanism1described hereinafter.

The pair of screw poles12have, mounted on bottom ends thereof, respectively, synchronization pulleys15engaged with a synchronous belt14. This synchronous belt14engages also a synchronization pulley17rotatable by drive of a motor16. The pair of screw poles12are therefore synchronously rotatable by drive of the motor16. With synchronous rotation of the pair of screw poles12, the crosshead13moves up and down axially of the screw poles12.

FIG. 2is a perspective view of the biaxial tension mechanism1noted above.FIG. 2shows a state of the upper unit2and lower unit3of the biaxial tension mechanism1connected to each other.

This biaxial tension mechanism1includes a first rail23and a second rail24arranged on the surface of a base portion26to extend in directions perpendicular to each other. The base portion26which supports the first rail23and second rail24is disposed on the base block11in a material testing machine body shown inFIG. 1.

The first rail23has a pair of first slide members21slidably arranged thereon. These first slide members21, by being guided by the first rail23, are movable toward and away from each other along a first axis parallel to the first rail23. One of these first slide members21is connected through a load cell27to a chuck25for gripping a specimen100. The other of the first slide members21is connected directly to a chuck25. Each of the first slide members21holds a seat member31having seat surfaces29formed thereon as described hereinafter. The first slide members21and seat members31constitute the first moving members in this invention.

On the other hand, the second rail24has a pair of second slide members22slidably arranged thereon. These second slide members22, by being guided by the second rail24, are movable toward and away from each other along a second axis parallel to the second rail24. One of these second slide members22is connected through a load cell27to a chuck25. The other of the second slide members22is connected directly to a chuck25. Each of the second slide members22holds a seat member31, as does each first slide member21. The second slide members22and seat members31constitute the second moving members in this invention.

The first and second rails23and24, first and second slide members21and22, seat members31, load cells27and chucks25arranged on the base portion26constitute the lower unit3of the biaxial tension mechanism1.

The biaxial tension mechanism1includes a support41connected by a connecting member42to the crosshead13in the material testing machine shown inFIG. 1. A load is applied from the crosshead13to the support41at the time of a biaxial tensile test described hereinafter. The support41has, attached thereto, a pair of lift members43used when the biaxial tension mechanism1or its upper unit2is transported by a forklift or the like. This support41acts as the load member according to this invention, to which a load is applied by the crosshead13acting as the loading mechanism.

The support41has, attached thereto, four link members44each pinched between a pair of joint members47. These link members44are attached to be rockable about pivots46relative to the joint members47. The support41and the four link members44attached to the support41by the joint members47and pivots46constitute the upper unit2of the biaxial tension mechanism1.

Of the joint members47supporting the four link members44, the joint members47corresponding to the first slide members21have, formed therein, bores49separately from the bores for receiving the pivots46. These bores49are used when changing a ratio between testing forces applied to the specimen100in the directions perpendicular to each other. In this case, two of the four link members44will be rock about the pivots46attached to the bores49.

FIG. 3is an explanatory view showing a state of a link member44attached to the support41.

As shown inFIGS. 2 and 3, each link member44is attached by the joint members47and pivot46to be rockable relative to the support41. With a projection48formed at the upper end of each link member44contacting a lower surface of the support41, rocking of the link member44is restricted to a position shown in a solid line inFIG. 3. Consequently, when the upper unit2and lower unit3are separated as described hereinafter, each link member44can be prevented from hanging down. The projection48formed on each link member44for contacting the lower surface of the support41acts as a restricting member for restricting a rocking range of each link member44.

FIG. 4is an explanatory view showing a state of a link member44attached to the support41according to another embodiment.

This embodiment omits the projection48formed at the upper end of each link member44in the embodiment described above, and provides a restricting pin55for restricting rocking of the link member44to a position shown in a solid line inFIG. 4. In this embodiment also, when the upper unit2and lower unit3are separated, each link member44can be prevented from hanging down. This restricting pin55acts as the restricting member for restricting the rocking range of each link member44.

Referring toFIG. 2again, each link member44has pins45arranged adjacent a lower end thereof. When the upper unit2and lower unit3are connected as described hereinafter, the pins45will contact the seat surfaces29formed on each seat member31.

Next, an operation for performing a biaxial tensile test on the specimen100using this biaxial tension mechanism1will be described.

As noted hereinbefore, the upper unit2of the biaxial tension mechanism1is attached to the crosshead13of the material testing machine. The lower unit3of the biaxial tension mechanism1is attached to the base block11of the material testing machine. In this state, the upper unit2is not located over the lower unit3of the biaxial tension mechanism1, and therefore an area over each chuck25in the lower unit3is open. The specimen100can therefore be loaded on these chucks25easily. Even if it is necessary to use a tool such as a spanner at the time of loading the specimen100, the operation can be carried out easily. In this state, in the upper unit2of the biaxial tension mechanism1, as shown inFIG. 3, the projection48formed at the upper end of each link member44is in contact with the lower surface of the support41, whereby each link member44is located in the position shown in the solid line inFIG. 3.

When the specimen100has been loaded on the chucks25and a biaxial tensile test is carried out on the specimen100, the crosshead13is lowered along with the upper unit2of the biaxial tension mechanism1by drive of the motor16shown inFIG. 1. This moves the pins45in the upper unit2into contact with the seat members31in the lower unit3.

FIG. 5is a perspective view showing a state of pins45and a seat member31coming into contact.FIG. 6is schematic side view of this state.

Each of the seat members31held by the first and second slide members21and22in the lower unit3has the seat surfaces29formed thereon for contacting the pins45disposed on the link member44in the upper unit2. The seat surfaces29and pins45have corresponding shapes.

When, after the specimen100is loaded, the crosshead13descends from the state shown inFIG. 1, the pins45attached to each link member44move into contact with the seat surfaces29formed on the seat member31as shown inFIGS. 5 and 6. When the crosshead13descends further from this state, the pins45slide on the seat surfaces29and contact side walls of the seat surfaces29as shown in solid lines inFIG. 6. At this time, the link member44rocks about the pivot46as shown in a phantom line inFIG. 3.

When the crosshead13descends further, the pins45in contact with the seat surfaces29press the seat member31. Such pressing forces move the pair of first slide members21away from each other as guided by the first rail23, and the pair of second slide members22away from each other as guided by the second rail24. At this time, outer circumferential surfaces of the pins45and the seat surfaces29of each seat member31make sliding movement. Consequently, tension loads are applied in the biaxial directions perpendicular to each other, to the specimen100gripped by the four chucks25. Values of the tension loads, i.e. testing forces, occurring at this time are measured by the pair of load cells27.

When the biaxial tensile test has been completed, the crosshead13is raised again along with the upper unit2of the biaxial tension mechanism1. When the upper unit2moves up, each link member44will rock under its own weight, which moves the pins45away from the side walls of the seat surfaces29. The seat surfaces29formed on each seat member31are open in other areas than in the direction in which the pins45make contact and apply the load. Thus, as the crosshead13moves further upward, the ascent of the link member44will result in the pins45separating from the seat surfaces29. At this time, as shown in the solid line inFIG. 3, the rocking of each link member44will stop in the position where the projection48formed at the upper end of the link member44contacts the lower surface of the support41. Thus, the rocking of the link member44can be maintained within a fixed range, thereby to prevent the link member44from hanging down.

When the crosshead13is again placed in a raised position as shown inFIG. 1, the specimen100will be removed from the chucks25. At this time also, the area over each chuck25in the lower unit3of the biaxial tension mechanism1is open, and therefore the specimen100can be removed from the chucks25easily.

This material testing machine has such a construction that enables not only the biaxial tensile test but an ordinary material test.FIG. 7is an explanatory view schematically showing a state of carrying out an ordinary tensile test with this material testing machine.

As shown inFIG. 7, an upper adapter61for attaching an upper gripper63is detachably attachable by a screw mechanism to the support41connected to the crosshead13. The upper gripper63is attached to the upper adapter61using pins62. On the other hand, a lower adapter64for attaching a lower gripper66is detachably attachable by screws69to the base portion26and base block11. As shown in this figure, the upper adapter61for attaching the upper gripper63is attachable to the crosshead13through the support41, and the lower adapter64for attaching the lower gripper66is attachable to the base block11through the base portion26. This construction enables the material testing machine to perform both the ordinary material test and the biaxial tensile test.

In the foregoing embodiment, as shown inFIGS. 5 and 6, each seat member31has the seat surfaces29which are open in all directions other than the direction in which the pins45make contact and apply the load. However, the seat surfaces29of each seat member31are not limited to such shape.

FIG. 8is a schematic side view showing, along with a pin45, a seat member32according to a second embodiment.

This seat member32has a configuration having a V-shaped opening formed in an upper part thereof, and a U-shaped opening formed in a lower part and corresponding to the shape of the pins45. This seat member32is shaped to be open upward, which is a direction other than the direction of load application between the pins45and the seat member32. Also when such seat members32are used, the upper unit2and lower unit3of the biaxial tension mechanism1are easily separable by moving the pins45away from the seat members32. It is also possible to connect the upper unit2and lower unit3for applying the testing force to the specimen100.

FIG. 9is a schematic side view showing, along with a link member51, a seat member33according to a third embodiment.

This seat member33has a similar shape to the seat member31in the first embodiment. On the other hand, the link member51in this embodiment has a forward end thereof acting as a contact portion shaped to correspond to a seat surface of the seat member33. Also when such seat members33and link members51are used, the upper unit2and lower unit3of the biaxial tension mechanism1are easily separable by moving the link members51away from the seat members33. It is also possible to apply the testing force to the specimen100with the contact portions at the forward ends of the link members51pressing the seat surfaces of the seat members33.

FIG. 10is a schematic side view showing, along with a link member52, a pin34used in place of each of the seat members31,32and33described hereinbefore.

In this embodiment, the pin34used in place of each of the seat members31,32and33described hereinbefore. Such pins34are supported by the first slide members21and second slide members22. On the other hand, in this embodiment, each link member52has a seat surface formed at a forward end thereof and shaped to correspond to each pin34. Also when such pins34and link members52are used, the upper unit2and lower unit3of the biaxial tension mechanism1are easily separable by moving the link members52away from the pins34. It is also possible to apply the testing force to the specimen100with the seat surfaces at the forward ends of the link members52pressing the pins34.

As described above, the seat surfaces and contact portions in this invention have a characteristic construction for contacting each other to transmit forces in a situation of performing a material test. In a different situation, the seat surfaces and contact portions can easily be moved out of contact and separated from each other.

The foregoing embodiments have been described taking the case of performing a biaxial tensile test, for example, which applies to the specimen100tensile forces in the directions perpendicular to each other by using the first rail23and second rail24arranged on the surface of the base portion26to expend perpendicular to each other, and moving the pair of first slide members21and the pair of second slide members22in the directions perpendicular to each other. This invention may be applied to a material testing machine for performing a triaxial tensile test, which machine includes the first rail23and second rail24arranged to cross each other, and further includes a third rail arranged to cross the first and second rails. Tensile forces are applied to the specimen tensile forces in triaxial directions by sliding third slide members connected to chucks along this third rail. It is also possible to apply this invention to a machine for performing a material test by applying to the specimen tensile forces in quadraxial or more directions.

This application claims priority benefit under 35 U.S.C. Section 119 of Japanese Patent Application No. 2014-099496 filed in the Japanese Patent Office on May 13, 2014, the entire disclosure of which is incorporated herein by reference.