JP2016217456A - Screw type clamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dropping accident of a workpiece even under a decreased clamping force by increasing a holding force more than a prior art screw type clamp.SOLUTION: This invention relates to a screw type clamp where a workpiece 1 is lifted up under a state in which the workpiece is held between a socket 12 fitted rotatably and in slanting manner to a leg 11 of a clamp main body 10 and a fastening bolt 14 installed at a leg 13 so as to be freely advanceable/retreatable. A hanging hole 21 is arranged in such a way that its center is placed at a position displaced from an opening center line to the leg 13 and a gravity center of the workpiece is always positioned closer to the leg 11 side than the hanging hole center line C . If this invention is formed as a two-hole type in which there is provided a second hanging hole 23 having a center at a position displaced from the opening center line toward the leg 11, the hanging hole capable of attaining the longer inter-distance L2 between the hanging center and the gravity center can be selected for use in response to a thickness of the workpiece, thereby a maximum holding force can be realized.SELECTED DRAWING: Figure 1

Description

The present invention relates to a screw-type clamp with an increased kink force.

A clamp body having a suspension hole at the top and a pair of opposing legs sandwiching a downward opening into which a workpiece is inserted below, and one leg of the clamp body are rotatably and tiltably mounted. A screw-type clamp having a catcher and a tightening bolt that is movably attached to the other leg of the clamp body is known, and an example thereof is shown in FIG. One leg portion 11 of the clamp body 10 is provided with a receiving metal 12 having an engagement tooth (not indicated) at its tip so as to be rotatable and tiltable, and a fastening bolt 14 can be advanced and retracted to the other leg portion 13. Is provided.

The receiver 12 is supported by a bearing 16 disposed in the leg portion 11 so as to be rotatable in all directions, and is axially opposed to the spring force of a coil spring 17 mounted between the opening end of the leg portion 11. It can be moved backwards.

A pressure nut 18 is attached to the leg portion 13. The pressure nut 18 cannot rotate relative to the leg portion 13 and can move backward in the axial direction against the spring force of the coil spring 19 disposed on the outer periphery of the pressure nut 18. The coil spring 19 has a larger spring force than the coil spring 17. A female screw (not shown) is cut on the inner surface of the pressure nut 18, and a fastening bolt 14 is screwed into the female screw so as to be movable in the axial direction. A pad 20 having tip engagement teeth is detachably / replaceably attached to the tip of the tightening bolt 14.

In the above configuration, the work bolt (flat steel plate) 1 inserted into the downward opening 22 is sandwiched between the receiving metal 12 and the fastening bolt 14 and the fastening bolt 14 is rotated by the operation of the handle 15 to receive the receiving metal 12. By moving the workpiece 1 in a direction, the workpiece 1 is brought into a pressed and clamped state, and when the tightening bolt 14 is further tightened by operating the handle 15 from this state, first the receiver 12 resists the spring force of the coil spring 17. When the clamp bolt 14 is further tightened by operating the handle 15 after the receiver 12 is moved backward in the direction of being embedded in the leg 11 and thus the receiver 12 is moved to the innermost position, the pressure nut 18 is moved to the coil spring 19. It moves backward in the direction of being buried in the leg 13 against the spring force.

When an initial tightening force is applied to the workpiece 1 in this manner, a suspension material such as a chain sling is connected to the suspension hole 21 via a metal fitting, a coupling, or the like and lifted by a crane (none of which is shown). The weight of the work 1 acts as a suspension load W and attempts to drop, but the follower 12 rotates and tilts (tilt angle θ) following this, and as shown in FIG. The engagement teeth located at the side of the workpiece bite into the side surface 2 of the workpiece 1 to give a clamping force F, thereby preventing the workpiece 1 from falling. The clamping force F at this time is calculated by F = D / d × W × μ (μ: coefficient of friction between the tip of the receiver 12 that gives the initial tightening force and the side surface 2 of the workpiece). Since it becomes 2 to 3 times, in many cases, it is possible to sufficiently secure the safety of lifting and carrying work.

Japanese Patent Laid-Open No. 10-037919

However, due to inadequate tightening by the operation of the handle 15, the friction coefficient μ at the initial tightening is small, or even if the initial tightening force is sufficient, the workpiece 1 is separated from other materials during lifting and transporting. When the contact generates vibration or an alternating load is applied to the workpiece 1, the initial tightening force is loosened, the clamping force F is reduced, and the workpiece 1 is dropped.

As a result of earnest research and experiment on the cause investigation and prevention measures, the inventors have determined that the workpiece 1 and the suspension hole are separated from the clamping force F that holds the workpiece 1 between the receiving metal 12 and the fastening bolt 14. The kink force due to the vertical positional relationship with the screw 21 is important, and the kink force is not effectively exhibited in the conventional screw clamp in which the suspension hole 21 and the opening 22 are generally arranged on the same center line C. I found that this is a major cause.

Here, the prying force is based on the principle of leverage, and as described with reference to FIG. 7, the upper end of the inner periphery of the suspension hole 21 to which a suspension material such as a chain sling is connected via a metal fitting or a coupling. The position is the force point Pf, and the position where the tip engaging tooth of the clamping bolt 14 (pad 20) contacts the work side surface 3 is the fulcrum Ps. The position at which the surface abuts against the workpiece side surface 2 is the action point Pa. When the distance between the perpendiculars of the suspension hole center line C and the workpiece center of gravity is L, and the contact area radius of the tip engaging teeth of the tightening bolt 14 (pad 20) contacting the workpiece side surface 3 is r, the bending force P is , P = L / r × W × μ (W: suspension load, μ: friction coefficient). Therefore, with the same screw type clamp, the prying force P is proportional to the distance L1 between the suspension center and the center of gravity.

FIG. 7 shows a state in which the workpiece 1 having a relatively small thickness is lifted by the screw clamp, and a certain distance L = L1 is left between the center of gravity of the workpiece 1 and the suspension hole center line C. However, as described above, in the conventional screw type clamp, since the suspension hole 21 and the opening 22 are generally arranged on the same center line C, the distance L1 is relatively small, and thus the obtained force P Is also relatively small. In addition, when the thickness of the work 1 is increased from the illustrated example, the distance L1 is gradually reduced, so that the kink force P is further reduced. When the work center of gravity coincides with the suspension center C, L1 = 0 is obtained. The kink force P is also P = 0. This is presumed that when the clamping force F is reduced, a sufficient prying force P for holding the workpiece 1 cannot be applied, causing a fall accident.

Therefore, the problem to be solved by the present invention is to provide a new screw-type clamp structure capable of increasing the knurling force compared to the conventional screw-type clamp, and even if the clamp force is reduced, the workpiece is dropped. Is to prevent this.

In order to achieve this object, the present invention according to claim 1 includes a clamp body having a pair of opposing legs with a downward opening through which a workpiece is inserted, and a suspension hole on the upper side. Receiving a workpiece inserted into the opening, having a receiver mounted rotatably and tiltably on one leg of the main body and a tightening bolt mounted on the other leg of the clamp main body so as to be able to advance and retract. In a screw-type clamp in which a suspension material such as a chain sling is locked in a suspension hole while being sandwiched between a bolt and a fastening bolt and lifted by a crane or the like, the suspension hole extends from the center line of the opening to the other leg side. The center of gravity of the workpiece is located on the one leg side from the center line of the suspension hole, even when lifting a workpiece of any thickness within the range allowed by the screw-type clamp. Is configured to be located in Characterized in that it comprises.

According to a second aspect of the present invention, in the screw clamp according to the first aspect, in addition to the suspension hole, a second suspension hole having a center at a position deviated from the center line of the opening toward the one leg side. It is characterized by providing.

According to the first aspect of the present invention, even when a workpiece having any thickness within the range allowed by the screw clamp is lifted, the center of gravity of the workpiece is located on the one leg side from the center line of the suspension hole. The distance between the center of gravity of the workpiece and the center line of the suspension hole is always ensured to be a certain distance or more, and the workpiece can be held with a kink force corresponding to the distance. Therefore, even in a situation where the clamping force does not work for some reason, the workpiece can be held with a kneading force to prevent the workpiece from falling, and the safety of lifting and transporting operations can be ensured.

According to the second aspect of the present invention, there is provided a clamp configuration having two suspension holes: a suspension hole at the center position biased toward the tightening bolt side of the opening and a suspension hole at the center position biased toward the metal receiving side of the opening; Therefore, a large prying force can be applied by selecting and using any one of the suspension holes according to the thickness of the workpiece. More specifically, in the case of a workpiece having a small plate thickness, the former suspension hole is used, and in the case of a workpiece having a large plate thickness, the latter suspension hole is used, so that the suspension hole center line and the side surface on the other leg side are Since a sufficient gap distance is ensured and a large kink force is exhibited, it is more effective in preventing the workpiece from falling.

It is a front view which shows the state which lifted the workpiece | work with comparatively small plate | board thickness with the screw type clamp by one Embodiment of this invention, and also demonstrates the koji which acts in this case. It is a side view of this screw type clamp. It is a front view which shows the state which lifted the workpiece | work of prescribed | regulated maximum thickness with this screw type clamp, and also demonstrates the koji which acts in this case. It is a front view which shows the state which lifted the workpiece | work using one suspension hole of the screw type clamp which has two suspension holes by other embodiment of this invention, and also demonstrates the koji which acts in this case. It is a front view which shows the state which lifted the workpiece | work of the prescription | regulation maximum thickness using the other suspension hole of this clamp, and also demonstrates the koji which acts in this case. It is a front view which shows the state (state where a clamping force works) which lifted the workpiece | work with the screw type clamp by a prior art, and also demonstrates the clamping force which acts in this case. It is a front view which shows the state which lifted the workpiece | work with comparatively small plate | board thickness with the screw type clamp by the prior art, and also demonstrates the koji which acts in this case.

Hereinafter, the present invention will be described in detail with reference to examples.

A threaded clamp according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. Similar to the conventional screw type clamp described with reference to FIG. 6, this screw type clamp has a pair of suspension holes 21 on the upper side and a downward opening 22 into which the workpiece 1 is inserted below. A clamp body 10 having opposing leg portions 11 and 13, a receiver 12 that is rotatably and tiltably attached to one leg portion 11 of the clamp body 10, and can be moved forward and backward to the other leg portion 13 of the clamp body 10. And a clamping bolt 14 (more specifically, a pad 20 attached to the tip of the work 1 inserted in the opening 22 and the same applies to the following). In this state, a suspension material such as a chain sling is locked in the suspension hole 21 and is lifted by a crane or the like (both not shown). The operation at this time is also as described above in relation to the prior art, and the workpiece 1 is held with the clamping force F calculated by the calculation formula of F = D / d × W × μ.

The difference between this screw-type clamp and the conventional screw-type clamp is that the center line of the suspension hole 21 and the opening 22 coincides with each other in the conventional screw-type clamp. As is apparent, the suspension hole 21 is formed so as to have a center at a position deviated from the center of the opening toward the leg 13. As a result, the center of gravity of the workpiece 1 (the center of thickness when the workpiece 1 is a flat steel plate) is the hanging hole, even when the workpiece 1 having any thickness within the allowable range of the screw clamp is lifted. A gap of a distance L2 is formed between the center of gravity of the workpiece and the center line C of the suspension hole, which is located on the leg 11 side or the receiver 12 side from the center line C.

FIG. 1 shows a state in which a workpiece 1 having the same thickness as that of the workpiece 1 lifted by the screw-type clamps shown in FIGS. 6 and 7 shown as the prior art is lifted. L2 is compared to the distance L1 between the center of gravity and the center of gravity L1 (FIG. 7) when the workpiece 1 having the same thickness is lifted by a conventional screw type clamp in which the center of the suspension hole coincides with the center of the opening. The amount of deviation biased toward the leg 13 of the clamp body 10 is increased (L2> L1). Therefore, the kink force P calculated by the formula of P = L / r × W × μ is also L2 / L1 times the kink force P obtained in the case of the prior art.

FIG. 3 shows a state in which the workpiece 1 having the maximum thickness allowed by the screw-type clamp is lifted. In this case as well, the center of gravity of the workpiece 1 is located on the leg 11 side of the suspension hole center line C. Thus, a suspension center / center-of-gravity distance L2 of a certain dimension or more is ensured, and a prying force P corresponding to this is obtained. That is, as in this embodiment, the center line C of the suspension hole 21 is close to or substantially coincides with the inner surface of the leg body 13 of the clamp body 10 facing the opening 22 (or a position beyond the inner surface). 3), if the workpiece 21 having any thickness within the allowable range of the screw clamp is to be lifted, L2 in FIG. 3 is set to the minimum value. Thus, a suspension center / center-of-gravity distance L2 that is equal to or larger than a certain dimension is secured, and the workpiece can be held with a kink force P corresponding to the distance. Therefore, even in a situation where the clamping force F does not work for some reason, the workpiece 1 can be held with the kink force P to prevent the workpiece 1 from falling, and the safety of lifting and transporting operations can be ensured.

The screw-type clamp of this embodiment includes a suspension hole 21 having a center at a position deviated from the center of the opening toward the leg 13 and a suspension hole 23 having a center at a position deviated from the center of the opening toward the leg 11. This is different from the screw clamp of the first embodiment in that it is a two-hole type screw clamp. When lifting the workpiece 1, a suspension material such as a chain sling is connected to one of the two suspension holes 21, 23 via a metal fitting or a coupling, depending on the thickness of the workpiece 1. Thus, there is an advantage that the suspension can be lifted using the suspension hole that can take a larger distance L2 between the suspension center and the center of gravity.

FIG. 4 shows a state in which the workpiece 1 having a relatively small plate thickness is lifted by the two-hole type screw-type clamp. In this case, similarly to the suspension hole 21 in the screw-type clamp of the first embodiment. It is preferable to lift the workpiece 1 using the suspension hole 21 whose center is located on the center line C1 biased toward the leg 13 side from the center of the opening. By doing so, the suspension center / center-of-gravity distance L2 can be increased, so that the kink force P also increases.

FIG. 5 shows a state in which the workpiece 1 having the maximum thickness allowed by the two-hole type screw clamp is lifted. In this case, the center is positioned on the center line C2 biased toward the leg 11 side. It is preferable to lift the workpiece 1 by using another suspension hole 23 to be used. By doing so, the suspension center / center-of-gravity distance L2 can be increased, so that the kink force P also increases.

When the workpiece 1 is lifted by being sandwiched between the receiver 12 and the fastening bolt 14, the receiver 12 is rotatable and tiltable but does not move in the axial direction. Although the tip position does not move greatly based on the reference, the fastening bolt 14 moves in the axial direction and contacts the side surface 3 of the workpiece 1 according to the thickness of the workpiece 1. It varies greatly depending on the thickness of the workpiece 1 to be lifted. Therefore, in many cases, by using the suspension hole 21 having the center on the center line C1 greatly deviated from the workpiece side surface 2, a sufficient distance L2 between the suspension center / center of gravity is ensured, and a large bending force P However, when the thickness of the workpiece 1 to be lifted is close to the maximum, as shown in FIG. 5, the distance L2 between the suspension center and the center of gravity is larger when the workpiece is lifted using another suspension hole 23. Thus, the kink force P can be increased. That is, if a two-hole type screw-type clamp as shown in FIGS. 4 and 5 is used, any one of the suspension holes is provided so that a larger suspension center / center-of-gravity distance L2 can be obtained according to the thickness of the workpiece. By selecting and using, there is an advantage that the maximum kink force P can be exhibited.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to this, and various modifications can be made within the scope of the invention defined in the claims.

1 Workpiece (flat steel plate)
2, 3 Workpiece side surface 10 Screw type clamp 11 Leg (one leg)
12 Receptacle 13 Leg (the other leg)
14 Clamping bolt 15 Handle 16 Bearing 17 Spring 18 Pressure nut 19 Spring 20 Pad 21 Suspension hole 22 Opening 23 Suspension hole (second suspension hole)
C, C1, C2 Hanging hole center line (hanging center)
F Clamping force P Prying force

Claims (2)

A clamp body having a suspension hole at the top and a pair of opposing legs sandwiching a downward opening into which a workpiece is inserted below, and one leg of the clamp body are rotatably and tiltably mounted. It has a catcher and a fastening bolt that is mounted on the other leg of the clamp body so that it can move forward and backward, and the work piece inserted into the opening is chained to the suspension hole while being sandwiched between the catcher and the fastening bolt. In a screw-type clamp that locks a suspension material such as a sling and lifts it with a crane or the like, the suspension hole has a center at a position deviated from the center line of the opening toward the other leg, and the screw-type clamp is allowed. The screw type is configured so that the center of gravity of the workpiece is positioned on the one leg side from the center line of the suspension hole, even when a workpiece of any thickness within the range to be lifted is lifted Clamp. The screw-type clamp according to claim 1, further comprising a second suspension hole having a center at a position deviated from the center line of the opening toward the one leg side in addition to the suspension hole.