Retaining mechanism for connecting pins

Abstract

To provide a retaining structure of a connection pin which is simple in structure and is capable of improving assembly property in a narrow space.SOLUTION: A retaining structure is applied to a pin connection portion of a construction machine and retains a connection pin 23 in a state in which the connection pin and connection members 21, 22 having pin insertion holes are detachably fitted together. Since the connection pin includes a pin body 24 extending in an axial direction and a flange 25 provided on an outer peripheral portion of one axial end of the pin body, and a bolt insertion hole 24a penetrating the pin body in the axial direction is provided, a cap 26 arranged at the other end in the axial direction can be fastened to the pin body with a bolt 27 inserted from the one end side in the axial direction. The flange has a tool engaging portion 25a restricting a rotation of the connection pin. The cap is formed in a disk-like shape with a diameter larger than that of the pin body, and has a rotation restricting portion that restricts relative rotation with the pin body when the bolt is temporarily tightened.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a retaining structure for a connecting pin, and more particularly to a retaining structure for a connecting pin used in a connecting portion of a construction machine.

Background Art

[0002] In construction machines, a retaining structure using a split pin is known as a means for preventing a connecting pin from coming out of a pin hole in a state where the connecting pin and a connecting member having a pin hole are detachably fitted together. As shown in FIG. 8, the split pin 100 is assembled together with a flat washer 104 to a portion protruding from the pin hole in a state where the connecting pin 103 is inserted through the overlapping portion of the connecting members 101 and 102. Since the split pin itself can be fixed by simply opening and bending the tip portion, it has been widely used as a simple retaining structure. In addition, a configuration using a retaining plate bolted instead of a split pin is also known for an exposed portion that is easily damaged (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described retaining structure, a working space for attaching a split pin or a retaining plate to the tip side of the connecting pin is created, so that the retaining can be performed without any particular inconvenience. However, when the pin joint is inside a structure such as a body frame, the working space is severely limited, which is a factor that greatly reduces the workability during assembly and disassembly.

[0005] Therefore, the present invention aims to provide a connecting pin retention structure that has a simple structure while improving ease of assembly in confined spaces. [Means for solving the problem]

[0006] To achieve the above objective, the connecting pin retention structure of the present invention is used in construction machinery. Located within the aircraft frame In a retaining structure provided at a pin joint, which prevents the connecting pin from coming loose when the connecting pin and the connecting member having a pin insertion hole are detachably fitted together, the connecting pin has a pin body extending in the axial direction and a flange provided on the outer circumference of one axial end of the pin body, and a bolt through hole is provided that penetrates the pin body in the axial direction, so that a cap disposed at the other axial end can be fastened to the pin body with a bolt inserted from the axial end side, the cap is formed in a disc shape with a larger diameter than the pin body, and has a rotation restricting part that restricts relative rotation with respect to the pin body in a temporary tightening state where the pin body is pressed in the axial direction by tightening the bolt, and the flange is such that the bolt when the rotation restricting part is functioning Using the first tool Restricts the rotation of the connecting pin by tightening. , engage the second tool It is characterized by having a tool engagement portion.

[0007] Furthermore, the rotation restricting portion is characterized by having a shape that can engage with the uneven shape provided on the tip of the pin body. In addition, the bolt is a socket head cap bolt, and one end of the pin body is provided with a counterbore for housing the head of the socket head cap bolt. [Effects of the Invention]

[0008] According to the connecting pin retention structure of the present invention, an axial bolt through hole is provided in the connecting pin, and a cap positioned at the other axial end is fastened with a bolt inserted from the axial end. Therefore, even if the tip (other end) of the connecting pin is located in a recessed area of ​​the structure, once the cap is positioned, it is possible to insert the bolt from the front and proceed to the preliminary tightening stage where the rotation restricting part is activated. Then, by engaging a tool with the tool engagement part of the flange with one hand to restrict the rotation of the connecting pin, and tightening the bolt with a tool held in the other hand, the rotation is restricted without causing the cap to rotate along with it, and the required axial force of the bolt can be obtained. This simple operation allows the flange and cap to maintain an appropriate distance from each other while restricting the axial movement of the connecting pin, thus contributing to improved workability when preventing the connecting pin from coming loose in confined spaces. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of a connecting pin retention structure illustrating one embodiment of the present invention. [Figure 2] This is also a perspective view of the main parts. [Figure 3] This is also a perspective view from the tip side of the connecting pin. [Figure 4] This is a perspective view of a modified example of the connecting pin, seen from the tip side. [Figure 5] This is also a perspective view of the connecting pin from the flange side. [Figure 6] This is a perspective view of a modified example of the connecting pin, seen from the flange side. [Figure 7] This is a side view of a pile driver, illustrating an example of a construction machine to which the present invention can be applied. [Figure 8] This diagram shows a conventional retaining structure for connecting pins. [Modes for carrying out the invention]

[0010] Figures 1 to 7 show an example (including modifications) of the connecting pin retention structure of the present invention. Figure 7 shows a pile driver, which is an example of a construction machine to which the present invention can be applied. The pile driver 11 comprises a base machine 14 consisting of a self-propelled lower traveling body 12 and an upper rotating body 13 that is rotatably mounted on the lower traveling body 12, a leader 15 erected at the front of the upper rotating body 13, and a luffing cylinder 16 that supports the leader 15 from the rear. In addition, an operator's cab 17 is provided on the right side of the upper rotating body 13, and an equipment room 18 housing the engine and hydraulic unit is provided on the left side.

[0011] The leader 15 is made up of multiple leader members connected to each other, each having a rectangular tubular cross-section, and a rotary drive device (not shown) that can move up and down along the leader 15 is mounted on its front. In addition, a top sheave block 19 is provided at the upper end of the leader 15, and a rope from a winch drum (not shown) mounted in the center of the upper slewing body 13 is wound around it, enabling the lifting of construction members (e.g., steel pipe piles).

[0012] The winch drum is equipped with a braking device that appropriately brakes a brake drum, which rotates integrally with it, to adjust the amount of rope paid out. The braking device operates a hydraulic linkage mechanism to tighten a brake band wrapped around the outer circumference of the brake drum. To obtain the tightening reaction force of the brake band, the linkage mechanism, for example, as simplified in Figure 1, has a pair of brackets 21, 21 in the width direction of the machine body on the bottom plate 20a of a box-shaped or boat-shaped machine frame 20, and two rod members 22, 22 that are pulled into the frame are pin-connected to these brackets 21, 21. Note that in Figure 1, a part of the machine frame 20 is cut out for easier understanding.

[0013] The bracket 21 and the rod member 22 serving as connecting members have a shape (forked portion 22a) where one end portion receives the other end portion, and are positioned near the side wall 20b of the aircraft frame 20 in a state where the axis C of the pin insertion hole (not shown) obtained by overlapping them with each other extends in the aircraft width direction. Also, as shown in FIG. 2, when inserting and fitting the connecting pin 23 into the pin insertion hole, the operator can perform the work in a posture that is not difficult by inserting the connecting pin 23 from the inside to the outside of the aircraft frame 20. However, such work is limited to one direction (from the inside to the outside) in terms of its structure when the distance between the bracket 21 and the side wall 20b is even closer, that is, in the wall-side work where the space between the bracket 21 and the side wall 20b becomes narrow.

[0014] Such a narrowly limited working space makes it particularly difficult to take measures (anti-loosening) to restrict the axial movement of the pin after inserting the connecting pin 23. Therefore, the pin coupling portion of the pile driver 11 is provided with a retaining structure for the connecting pin 23 that can improve the assemblability in the narrow portion.

[0015] As shown in FIG. 2, the retaining structure of the connecting pin 23 is a structure for preventing the connecting pin 23 from coming off in a state where the connecting pin 23, the bracket 21 having the pin insertion hole, and the rod member 22 are detachably fitted. The connecting pin 23 has a pin body 24 extending in the axial direction and a flange 25 provided on the outer peripheral portion at one axial end of the pin body 24. By providing a bolt through-hole 24a penetrating the center of the pin body 24 in the axial direction, the connecting members 21, 22 are sandwiched, and a cap 26 arranged at the other axial end (near the side wall 20b) can be fastened to the pin body 24 with a bolt 27 inserted from one axial end side (the side away from the side wall 20b).

[0016] The pin body 24 is formed, for example, with a diameter of 50 mm and a length of 80 mm in consideration of the design conditions for pin connection. As shown in FIG. 3, a radial plane cutting is performed on the tip of the pin through the bolt through-hole 24a, so that a groove portion continuous in the radial direction is formed in a direction orthogonal to the axis C, and a concave shape 28 with a step in the axial direction is provided.

[0017] The flange 25 has a tool engagement portion 25a for restricting the rotation of the connecting pin 23. The tool engagement portion 25a is composed of two parallel planes formed at positions facing each other across the bolt through-hole 24a. By engaging and holding a wrench corresponding to the width of the two surfaces, the rotation of the connecting pin 23 can be restricted (locked).

[0018] The cap 26 is formed in a disc shape with a larger diameter than the pin body 24, and a screw hole 26a for screwing with the bolt 27 is provided at the center. On the inner surface side of the cap 26, a convex shape 29 is provided as a rotation restricting portion that can engage with the concave shape 28 of the pin body 24 in a temporarily tightened state of the bolt 27. Thus, in the state where the connecting pin 23 is locked, even when the rotation (screw tightening) of the bolt 27 acts, the contact surfaces 28a and 29a in the rotation direction of the concave and convex shapes 28 and 29, that is, two planes parallel to the axis C of the pin insertion hole, contact each other and receive the rotation, and the relative rotation of the cap 26 with respect to the pin body 24 that tries to rotate along with the rotation due to the tightening of the bolt 27 is restricted.

[0019] Here, as a modified example, as shown in FIG. 4, the pin body 24 side can be made convex shape 30, and on the inner surface side of the cap 26, a concave shape 31 that can engage with the convex shape 30 can be provided. Even with such a configuration, the contact surfaces 30a and 31a in the rotation direction of the concave and convex shapes 30 and 31 contact each other and receive the rotation, and the relative rotation of the cap 26 with respect to the pin body 24 is restricted.

[0020] Furthermore, as shown in Figure 5, using a hexagonal bolt 27 with a sufficiently long shank length provides protection against rotational loosening due to vibration, but as a modified example, as shown in Figure 6, a hexagonal socket head bolt (cap screw) with a hexagonal hole formed in the head 32a of the bolt 32 can be used. In this case, a counterbore 33 corresponding to the size of the head 32a of the bolt 32 is provided in the pin body 24, and the bolted head 32a can be housed in the counterbore 33.

[0021] To prevent the connecting pin 23 from coming loose using the retaining structure formed in this manner, as shown in Figure 2, the axis C of the pin insertion hole is aligned at the overlapping portion of the connecting members 21 and 22, the connecting pin 23 is inserted through the pin insertion hole and assembled, and then the bolt 27 is inserted into the bolt through hole 24a of the connecting pin 23 and pushed through until it comes out on the opposite side of the connecting members 21 and 22.

[0022] Here, the prepared cap 26 is held in place against the tip (threaded portion) of the bolt 27 from the opposite side, and the bolt 27 is then tightened into the threaded hole 26a of the cap 26 with the other hand. At this time, the concave shape 28 of the pin body 24 and the convex shape 29 of the cap 26 are aligned, and the bolt 27 is temporarily tightened by engaging both 24 and 26 so that they cannot rotate relative to each other.

[0023] In this temporary tightening state, an axial pressing force (screw fastening force) is generated between the pin body 24 and the cap 26, so there is no need to worry about the cap 26 falling off during the work. Therefore, subsequent work can be performed on one side (the side away from the side wall 20b), that is, on the side aligned with the worker's line of sight. First, a wrench is engaged with the tool engagement portion 25a of the flange 25 and held in place to restrict the rotation of the connecting pin 23. Then, with the connecting pin 23 locked, the bolt 27 is tightened using another wrench. By tightening the bolt to the set torque in this way, the flange 25 and the cap 26 prevent the connecting pin 23 from coming loose by restricting its axial movement.

[0024] As described above, the connecting pin retention structure of the present invention is configured such that the connecting pin 23 is provided with an axial bolt through hole 24a, and the cap 26, which is positioned at the other axial end, is fastened with a bolt 27 inserted from the axial end. Therefore, even if the tip (other end) of the connecting pin 23 is located in a recessed area of ​​the structure, as long as the cap 26 is positioned, the bolt 27 can be inserted from the front and the work can proceed to the temporary tightening stage where the rotation restricting part (e.g., convex shape 29) is activated. Then, by engaging a tool with the tool engagement part 25a of the flange 25 with one hand to restrict the rotation of the connecting pin 23, and then tightening the bolt 27 with a tool held in the other hand, the rotation is restricted without causing the cap 26 to rotate along with it, and the necessary axial force of the bolt 27 can be obtained. This simple operation allows the flange 25 and the cap 26 to maintain an appropriate distance from each other while restricting the axial movement of the connecting pin 23, thus contributing to improved workability when preventing the connecting pin 23 from coming loose in confined spaces.

[0025] Furthermore, since the uneven shapes 29 and 31 that serve as rotation restricting parts of the cap 26 are shaped to engage with the uneven shapes 28 and 30 provided at the tip of the pin body 24, a symmetrical shape (unevenness) that straddles the rotation axis can be easily obtained from the pin material, enabling engagement suitable for the axis that receives rotation. In addition, since a counterbore 33 for housing the head 32a of the hex socket head bolt 32 is provided on one end of the pin body 24a, not only is workability improved, but the protrusion of the head 32a is also eliminated, resulting in a highly safe retaining structure for the connecting pin 23.

[0026] Although the present invention uses a pile driver as an example of construction machinery, it is not limited to this and can be applied to various parts of construction machinery equipped with excavation devices and material handling devices, such as earth drills and cranes, as a retaining structure for connecting pins. In this case, the retaining structure, which can be implemented in a small space, expands the design flexibility, including the arrangement of equipment, and enables smooth model changes and new model development. [Explanation of symbols]

[0027] 11...Pile driver, 12...Lower traveling body, 13...Upper rotating body, 14...Base machine, 15...Leader, 16...Lowing cylinder, 17...Operator's cab, 18...Equipment room, 19...Top sheave block, 20...Machine frame, 20a...Bottom plate, 20b...Side wall, 21...Bracket, 22...Rod member, 22a...Bifurcation, 23...Connecting pin, 24...Pin body, 24a...Bolt through hole, 25...Flange, 25a...Tool engagement part, 26...Cap, 26a...Screw hole, 27...Bolt, 28...Concave shape, 28a...Contact surface, 29...Convex shape, 29a...Contact surface, 30...Convex shape, 30a...Contact surface, 31...Concave shape, 31a...Contact surface, 32...Bolt, 32a...Head, 33...Counterbor

Claims

1. In a pin joint provided within the frame of a construction machine, a retaining structure is provided to prevent the connecting pin from coming loose when the connecting pin and the connecting member having a pin insertion hole are detachably fitted together, The connecting pin has a pin body extending in the axial direction and a flange provided on the outer circumference of one axial end of the pin body, and is provided with a bolt through hole that penetrates the pin body in the axial direction, so that a cap disposed at the other axial end can be fastened to the pin body with a bolt inserted from the axial end side. The cap is formed in a disc shape with a larger diameter than the pin body, and has a rotation restricting portion that restricts relative rotation with respect to the pin body when the pin body is pressed axially by tightening the bolt. The connecting pin retention structure is characterized in that the flange has a tool engagement portion for engaging a second tool, which restricts the rotation of the connecting pin by tightening the bolt with a first tool from a state in which the rotation restricting portion is functioning.

2. The connecting pin retaining structure according to claim 1, characterized in that the rotation restricting portion has a shape that can engage with the uneven shape provided at the tip of the pin body.

3. The aforementioned bolt is a socket head cap bolt, The retaining structure for a connecting pin according to claim 1 or 2, characterized in that a counterbore for housing the head of the hexagon socket head bolt is provided on one end of the pin body.

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