Damage-free clamp

Abstract

This invention provides a non-damaging clamp that prevents serious risks leading to workpiece slippage accidents by providing a means to easily check for wear at the connection point between the crank cam and the telescopic rod without disassembling the clamp. [Solution] In the non-damaging clamp 10, a wear confirmation hole 40 is formed in the clamp body, allowing the wear condition of the connection between the crank cam 19 and the telescopic rod 24 to be visually inspected from the outside of the clamp body. The crank cam and the telescopic rod are connected by a connecting pin that protrudes from a screw thread 42 fixed to the upper end of the telescopic rod and is rotatably inserted into a pin insertion hole formed in the crank cam. The wear confirmation hole is formed in a position that is substantially aligned with the connecting pin and the pin insertion hole when the crank cam takes a position that holds the wedge body 17 in a standby position.

Description

Technical Field

[0001] The present invention relates to a non-destructive clamp configured to be able to lift a workpiece without damaging it, and particularly to a non-destructive clamp having a novel configuration provided with means for easily and constantly checking the wear state of the connection portion between specific parts.

Background Art

[0002] Non-destructive clamps by the present applicant are disclosed in Patent Documents 1 to 3. These non-destructive clamps are configured such that a pressing metal is provided on one of a pair of opposing legs sandwiching a slot, and a wedge body having a substantially triangular shape in plan view is provided on the other leg. With the vertical surface of the pressing metal abutting on one side surface of the workpiece inserted into the slot and the vertical surface of the wedge body abutting on the other side surface of the workpiece, the workpiece is lifted. Since the workpiece is lifted in a state of contacting the side surface of the workpiece with a surface without biting into protrusions such as teeth or claws, it not only prevents a decrease in the commercial value due to damage to the side surface of the workpiece, but also prevents a decrease in strength due to adversely affecting the internal structure of the metal material forming the workpiece.

[0003] The wedge has an inclined surface that is tilted at a predetermined angle with respect to a vertical gripping surface, and rack teeth (wedge rack teeth) are formed on this inclined surface. A guide plate having an inclined surface parallel to the inclined surface of the wedge is fixed to the other leg, and rack teeth (guide plate rack teeth) that can engage with the wedge rack teeth are formed on the inclined surface of this guide plate. When lifting a workpiece, when a predetermined operation is performed with the workpiece inserted into the slot, the tension of the coil spring causes the wedge to slide out into the slot along the inclined surface of the guide plate, and it contacts the side of the workpiece at a position corresponding to the thickness of the workpiece, and at this position the rack teeth engage with each other and hold it immovably. In this manner, when the workpiece is lifted with the vertical surfaces of the wedge and the clamp in contact with both sides of the workpiece, the wedge will attempt to move downward due to the load of the workpiece. However, since the wedge rack teeth are firmly engaged with the guide plate rack teeth, the reaction force from the workpiece prevents the wedge from moving backward upward, thus allowing the workpiece to be lifted safely without reducing the gripping force. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 61-27892 [Patent Document 2] Japanese Patent Publication No. 2007-076806 [Patent Document 3] Japanese Patent Publication No. 2024-124708 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The wedge body employs the configuration shown in Figures 5 and 6. Specifically, a screw thread 42 is fixed to the upper end of a telescopic rod 24, which is fitted with a coil spring 25. Connecting pins 42a protruding from both sides of the screw thread 42 are inserted into connecting holes 19a of the crank cam 19, thereby connecting the crank cam 19 to the telescopic rod 24. The lower end of the telescopic rod 24 is connected to the wedge body 17 by a connecting pin 36. When the crank cam 19 is moved from the standby position (Figures 2 and 5) to the operating position (Figure 4), which is approximately reversed, by operating the handle 22, the tension of the coil spring 25 acts, allowing the wedge body to slide along the inclined surface of the guide plate into the slot.

[0006] As is clear from the above explanation, in this non-damaging clamp, when attempting to lift a workpiece, it is necessary to reverse the crank cam from the standby position to the operating position, and after lowering the workpiece to the predetermined location, it is necessary to reverse the crank cam from the operating position to the standby position. Each time this happens, the connecting pin 42a of the screw thread 42 rotates within the connecting hole 41 of the crank cam 19, and repeated use causes wear on the connection, making it easy for the connecting pin 42a to come loose from the connecting hole 19a. If the telescopic rod 24 comes loose from the crank cam 19, the tension of the coil spring 25 attached to the telescopic rod 24 cannot be transmitted to the wedge body 17, and the wedge body 17 may move backward upward due to the reaction force received from the workpiece during lifting, potentially leading to a serious accident such as the workpiece sliding down.

[0007] To prevent such problems, conventionally, the undamaged clamps were periodically disassembled to check for wear on the connecting pin of the screw thread and / or the connecting hole of the crank cam at the connection point between the crank cam and the telescopic rod. However, this disassembly process was time-consuming and cumbersome, resulting in the disadvantage of shortening the usable time of the undamaged clamps.

[0008] Therefore, the problem that this invention aims to solve is to provide a means for easily confirming, without disassembly, that wear has occurred at the connection point between the crank cam and the telescopic rod in the intact clamp, thereby preventing serious risks that could lead to workpiece slippage accidents. [Means for solving the problem]

[0009] To solve this problem, the present invention according to claim 1 is a non-damaging clamp comprising: a clamp body formed in a substantially inverted U shape with a slot between a pair of legs; a suspension ring connected to the clamp body; a retaining plate provided on one leg of the clamp body; a wedge provided on the other leg of the clamp body; a guide plate fixed to the clamp body and having rack teeth that can mesh with the rack teeth of the wedge; a crank cam provided on the clamp body so as to be rotatable between a first position and a second position about a fixed axis; an extendable rod connecting the wedge and the crank cam; and a spring wound around the extendable rod and biasing the wedge in a direction to move it downward relative to the guide plate, wherein when the crank cam is in the first position, the wedge is made movable downward relative to the guide plate by the biasing force of the spring, and when the crank cam is in the second position, the wedge is held in a standby position without the biasing force of the spring, characterized in that a wear confirmation hole is formed in the clamp body so as to be able to visually check the wear state of the connection part between the crank cam and the extendable rod from the outside of the clamp body.

[0010] The present invention according to claim 2 is characterized in that, in the non-damaging clamp according to claim 1, the crank cam and the telescopic rod are connected by a connecting pin that protrudes from a screw thread fixed to the upper end of the telescopic rod being rotatably inserted into a pin insertion hole formed in the crank cam, and the wear confirmation hole is formed at a position that substantially aligns with the connecting pin and the pin insertion hole when the crank cam is in the second position. [Effects of the Invention]

[0011] According to the present invention as described in claim 1, a wear confirmation hole is formed in the clamp body, which allows the wear condition of the connection between the crank cam and the telescopic rod to be visually inspected from the outside of the clamp body. This makes it possible to easily check the wear condition of the connection without disassembling the clamp, thereby preventing serious risks that could lead to workpiece slippage accidents.

[0012] According to the present invention as described in claim 2, a wear confirmation hole is formed at a position substantially aligned with the connection portion when the crank cam is in the standby position. Therefore, for example, before lifting a workpiece using a non-damaging clamp, the wear condition of the connection portion can be visually checked by looking inside through the wear confirmation hole. If no wear that raises safety concerns is found, the work can be continued, eliminating the need to unnecessarily disassemble the device to check the wear condition. Conversely, if wear that raises safety concerns is found, the work can be immediately interrupted to perform a detailed inspection and replace necessary parts, thereby preventing serious risks that could lead to workpiece slippage accidents. [Brief explanation of the drawing]

[0013] [Figure 1] This is a front view of a non-damaging clamp in an unloaded state according to one embodiment of the present invention. [Figure 2] Figure 1 is a front view showing the internal mechanism clearly, with the main body plate on the front side of the paper omitted. [Figure 3] This is a side view of the undamaged clamp. [Figure 4] This is a front view showing the workpiece being lifted by this undamaged clamp (the main plate on the front side of the clamp body is not shown). [Figure 5] This is a magnified perspective view showing the connection between the wedge and the crank cam in this intact clamp. [Figure 6] Figure 5 is an exploded perspective view showing the crank cam and telescopic rod separately. [Best Mode for Carrying Out the Invention]

[0014] With reference to Figures 1 to 6, the configuration and operation of a non-damaging clamp 10 according to one embodiment of the present invention will be described in detail.

[0015] This undamaged clamp 10 has a clamp body 12 formed in a roughly inverted U shape when viewed from the front, from a pair of main plates 11, 11 that are spaced apart from each other and facing each other. Legs 14, 15 are formed on the lower part of the clamp body 12, flanking a slot 13 that opens downwards.

[0016] A guide plate 16, which is inclined at a predetermined angle to the vertical, is fixed to the leg portion 14 of the clamp body 12, and a wedge body 17 having rack teeth 17a that can engage with the rack teeth 16a of the guide plate 16 is arranged to move along the inclination of the guide plate 16. Multiple guide pins 37 (two in the illustrated embodiment) protruding from the inclined surface of the wedge body 17 (the surface on which the rack teeth 17a are formed) are inserted through a guide groove 16a (Figure 3) formed in the center of the width direction of the guide plate 16 so as to extend in the length direction, and nuts 18 are screwed onto the threaded tip portions of the guide pins 37 on the outside of the guide plate 16, thereby connecting the wedge body 17 to the guide plate 16 while allowing sliding movement relative to the guide plate 16. The engagement surface 17b of the wedge body 17 facing the slot 13 is a vertical surface that extends in a substantially vertical direction.

[0017] Above the foot portion 14, a wedge pushing crank cam 19 is rotatably supported on a shaft 20 fixed to the clamp body 12. In the no-load state, the crank cam 19 takes a position where two recesses 19a and 19b face downward (standby position: see Fig. 2), and the stopper pin 21 engages with one of the recesses 19a to hold the crank cam 19 in this position. When lifting the workpiece W, the crank cam 19 takes a position that is approximately half-rotated about the shaft 20 from this position (operating position: see Fig. 4), and the stopper pin 21 engages with the other recess 19b to hold the crank cam 19 in this position. One end of a handle 22 for pushing the wedge is fixed to the crank cam 19. By grasping a handle 23 protruding from the other end of the handle 22 that extends outside the clamp body 12 and rotating the handle 22 counterclockwise (the same applies to the rotation direction and the up / down, left / right directions in Fig. 1) from the standby position, the crank cam 19 can be moved to the operating position.

[0018] A rod 24 around which a compression coil spring 25 for pushing the wedge is wound is telescopic within a certain length range by having a small-diameter rod loosely fitted onto a large-diameter rod. By inserting connecting pins 42a protruding from both side surfaces of a threaded collar 42 fixed to the upper end of the rod 24 into pin insertion holes 41 of the crank cam 19, the crank cam 19 is connected so as to be relatively rotatable. Also, by inserting a connecting pin 36 through a pin insertion hole 35 formed at the lower end of the telescopic rod 24 and a pin insertion hole (not labeled) formed at the lower end of the wedge 17, the wedge 17 is rotatably connected to the lower end of the telescopic rod 24. When the crank cam 19 is in the standby position (Fig. 2), since the rotation shaft 20 of the crank cam 19 is slightly positioned to the left of the telescopic rod 24, the coil spring 25 applies a biasing force to rotate the crank cam 19 clockwise about the shaft 20. However, since the stopper pin 21 is fitted into the recess 19a, rotation in the same direction is blocked, and the crank cam 19 is held in the standby position.

[0019] Above the leg portion 15 of the clamp body 12, an L-link 26 is rotatably supported by an L-link bolt 27 fixed to the clamp body 12. The L-link 26 is further rotatably connected to the lower end of a suspension ring 29 by a suspension ring pin 28 and rotatably connected to the upper end of a pressing link 31 by a shaft pin 30. The lower end of the pressing link 31 is rotatably supported by a cam bolt 32 fixed to the clamp body 12. The shaft pin 30 passes through a long hole 33 formed at the upper end of the pressing link 31 and is movable within the length range of the long hole 33. When the intact clamp 10 is in the standby position (Figure 2), it is located at the upper end of the long hole 33, and is held at the same position when in the operating position (Figure 4) as long as normal lifting is being performed.

[0020] Furthermore, a pressing piece 35 is connected by a shaft 34 so as to be relatively rotatable near the lower end of the pressing link 31. When the crank cam 19 is held in the position shown in Figure 1, only a slight gap remains between the tip 26a of the L-link 26 and the tip 19c of the crank cam 19. Therefore, the L-link 26 cannot substantially rotate counterclockwise from this position, and the side surface 35a of the pressing piece 35 is designed to only provide a vertical surface that slightly protrudes into the slot 13 in the standby position (Figure 1).

[0021] When the undamaged clamp 10, configured as described above, is in the standby state (Figure 2), the workpiece W to be lifted is set in the slot 13 (the upper end of the workpiece W is inserted deep into the slot 13). Then, by holding the handle 23 from the outside of the clamp body 12 and rotating the handle 22 counterclockwise, the crank cam 19, which is fixed integrally with the handle 22, rotates in the same direction around the axis 20, and moves to the operating position where the stopper pin 21 is fitted into the recess 19b on the opposite side. As a result, the wedge body 17, which is connected to the crank cam 19 by the rod 24, moves downward due to its mass and the spring force of the coil spring 25 wound around the rod 24, and its vertical engagement surface 17b comes into contact with the right side of the workpiece W. At this time, the spring force of the coil spring 25 acts in a direction that presses the wedge body 17 against the guide plate 16, so that the rack teeth 17a of the wedge body 17 engage with the rack teeth 16a of the guide plate 16.

[0022] Furthermore, on the leg portion 15 side of the clamp body 12, the lock handle 38 is rotated counterclockwise around the axis 39 against the spring force of a spring (not shown). As a result, the moment the connecting axis between the cam guide 37 and the lock handle 38 crosses the straight line connecting axis 39 and axis 46, the spring force of the spring rotates the cam guide 37 clockwise, stopping when its tip 37a contacts the left side surface of the workpiece W. Consequently, the stopper cam 44 also rotates slightly clockwise around the cam bolt 32, but its tip engagement teeth remain embedded in the leg portion 15 and do not protrude into the slot 13, or even if the tip engagement teeth protrude slightly into the slot 13, their protrusion width is smaller than the protrusion width of the clamping plate side surface 35a, so it does not come into contact with the left side surface of the workpiece W, and a small gap remains between them (see Figure 4).

[0023] When the lifting ring 29 is attached to a crane or the like in the state shown in Figure 4 and the workpiece W is lifted, the workpiece W is pressed and clamped between the vertical engagement surface 17b of the wedge body 17, which is moving in the direction of entering the slot 13 from the leg portion 14 due to the spring force of the coil spring 25, and the vertical engagement surface 35a of the retaining plate 35, which is moving in the direction of entering the slot 13 from the leg portion 15 via the L link 26 and retaining link 31 due to the weight of the intact clamp 10 and the mass of the workpiece W, and is lifted and transported to a predetermined location.

[0024] As explained above, in the non-damaging clamp 10, the wedge body 17 prevents the workpiece W from sliding. Specifically, under the spring force of the coil spring 25, the wedge body 17 moves relative to the guide plate 16 to a position where its engaging surface 17b presses and clamps the workpiece W between itself and the clamping plate side surface 35a (a position where it presses against the workpiece side surface Wa), depending on the thickness of the workpiece W, and takes the position shown in Figure 4. Even if the workpiece W tries to slide from this position, the wedge body 17, whose engaging surface 17b is in contact with the workpiece side surface Wa, cannot move any further downward from this position, thus preventing the workpiece W from sliding through the frictional force acting on the workpiece side surface Wa. Furthermore, even if a force acts to raise the wedge body 17 relative to the guide plate 16 due to a reaction force from the workpiece W, the rack teeth 17a and 16a of the wedge body 17 and the guide plate 16 are engaged with each other, so this relative movement is restricted and a decrease in the gripping force on the workpiece W can be prevented.

[0025] Furthermore, the undamaged clamp 10 according to the illustrated embodiment incorporates a workpiece slip prevention device (see Patent Document 2) mainly composed of a stopper cam 44 and a safety cam guide 39, thus exhibiting a greater effect in preventing the workpiece W from falling. Specifically, when the workpiece W slides downward from its designated position (set deep inside the slot 13) and becomes dangerous, the tip 37a of the safety cam guide 37 is pushed deep into the slot 13 by the spring force of a spring (not shown), and consequently, the engaging teeth 36a of the stopper cam 36 are pushed into the slot 13 and bite into the side surface Wb of the workpiece that is about to slide, preventing the workpiece W from falling. The workpiece slip prevention device is not directly related to the means of this invention, so further explanation is omitted.

[0026] The configuration and operation described above are basically the same as those of the prior art, but this non-damaging clamp 10 is further equipped with a means to easily check for wear at the connection between the crank cam 19 and the telescopic rod 24 without disassembling it, thereby effectively preventing the risk of workpiece slippage accidents. Specifically, in the main body plates 11, 11 of this non-damaging clamp 10, a wear confirmation hole 40 is opened at a position aligned with the connection when the crank cam 19 is in the standby position (Figure 2), in other words, the position where the connecting pins 42a protruding from both sides of the screw threads 42 are inserted into the connecting holes 41 of the crank cam 19 at that position.

[0027] Therefore, when the crank cam 19 is in the standby position, for example, before attempting to lift a workpiece using the undamaged clamp 10, the wear condition of the connection part can be visually checked by looking inside through the wear confirmation hole 40. For example, if no wear that raises safety concerns is found on the connecting pin, the work can be continued as is, eliminating the need to unnecessarily disassemble and check the wear condition. Conversely, if wear that raises safety concerns is found, the work can be immediately stopped to perform a detailed inspection and replace necessary parts, thereby preventing serious risks that could lead to workpiece slippage accidents.

[0028] Although one embodiment of the present invention has been described in detail above, the present invention is not limited thereto, and various modifications can be taken within the scope of the invention as defined in the claims.

[0029] Double job 10 Damage-free clamps 11 Main panel 12 Clamp body 13 slots 14,15 Legs 16 Guide plate 16a Guide plate rack teeth 17 cuneiform 17a Wedge-shaped rack teeth 18 nuts 19 Crank Cam 20 Crank cam rotation axis 21 Stopper pin for wedge body insertion 22 Handle for wedge insertion 23 Handle 24 Telescopic Rods 25 Coil Springs 26 L-link 27 L-link bolt 28 Hanging ring pin 29 Hanging ring 30 axis pins 31 Retaining Link 32 Cam bolts 33 Slotted holes 34 axes 35. Presser foot 36 connecting pins 37 Guide pins 38 Locking Handle 39 Safety Cam Guide 40 Wear Inspection Holes 41 Pin insertion holes 42 Screw-on screws 42a Connecting pin 43 Pin insertion holes 44 Stopper Cam

Claims

1. A non-damaging clamp comprising: a clamp body formed in a substantially inverted U shape with a slot between a pair of legs; a suspension ring connected to the clamp body; a retaining plate provided on one leg of the clamp body; a wedge provided on the other leg of the clamp body; a guide plate fixed to the clamp body and having rack teeth that can engage with the rack teeth of the wedge; a crank cam rotatably mounted on the clamp body so as to be able to move between a first position and a second position about a fixed axis; an extendable rod connecting the wedge and the crank cam; and a spring wound around the extendable rod and biasing the wedge to move downward relative to the guide plate, wherein the wedge is made movable downward relative to the guide plate by the biasing force of the spring when the crank cam is in the first position, and the wedge is held in a standby position without the biasing force of the spring when the crank cam is in the second position, and a wear confirmation hole is formed in the clamp body so as to be able to visually check the wear state of the connection between the crank cam and the extendable rod from the outside of the clamp body.

2. The non-damaging clamp according to claim 1, wherein a connecting pin, which is formed to protrude from a screw thread fixed to the upper end of the telescopic rod, is rotatably inserted into a pin insertion hole formed in the crank cam, thereby connecting the crank cam and the telescopic rod, and the wear confirmation hole is formed at a position that substantially aligns with the connecting pin and the pin insertion hole when the crank cam is in the second position.

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