JP4300427B2 - Pin connection structure - Google Patents

Description

  The present invention relates to a pin coupling structure that couples two members constituting a front work machine of a construction machine so as to be relatively rotatable by pins, such as a boom and an arm constituting the front work machine of a hydraulic excavator. .

  As a construction machine, for example, a hydraulic excavator has a front work machine in order to perform excavation and other operations. This front work machine has a boom mounted on the upper swing body so as to be able to move up and down, an arm connected to the tip of the boom so as to be able to rotate in the vertical direction, and the tip of the arm can be relatively rotated via a link mechanism. And a front attachment such as a bucket connected to the. And between a boom and an arm, between an arm and a bucket, etc. are connected so that relative rotation is possible using a connecting pin.

  The connecting pin slides with one of the two members that are rotatably connected to each other, but does not rotate with respect to the other member, and is mounted so as not to come out of the pin insertion hole. . For example, in the connecting part between the boom and the arm, a collar part in a direction orthogonal to the axis line is attached to the connecting pin, and the collar part is brought into contact with the tip side part of the boom, and the collar part is connected to the connecting pin. The rotation is restricted so that it does not rotate about the axis of the shaft, and it is prevented from moving in the axial direction of the connecting pin, that is, it is prevented from coming off.

  For example, Japanese Patent Application Laid-Open No. H10-228707 discloses a configuration of the rotation preventing and retaining means for the connecting pin. According to the disclosure of Patent Document 1, a collar is attached to the end of the connecting pin, and the collar is positioned outside the tip end of the boom or the base end of the arm, usually the surface of the boom. It is mounted so as to abut on. By holding the collar portion fixedly, the connecting pin is prevented from rotating and coming off. That is, the rotation preventing member is a substantially U-shaped plate body in which the front end portion of the brim portion is inserted on the surface of the boom and the right and left regulating wall members or regulating walls are provided in order to regulate both side edges of the distal end. Consists of The detent member is fixed to the side of the boom by welding means, and the connecting pins connected to the brim portion are prevented from rotating relative to the boom by bringing both regulating walls into contact with both side edges of the brim portion. Retained. The retaining means includes a retaining plate abutting against the surface of the locking member. The retaining plate is mounted so as to cover the collar portion, and the retaining member is fastened to the locking member with a bolt. Assemble to wear.

As a result, with a simple configuration, the function of preventing the connection pin from rotating and retaining can be exhibited, and the relatively rotatable connecting portion between the boom and the arm can be stably held. Thus, the wear of the connecting pin is suppressed.
JP-A-8-158400

  However, Patent Document 1 described above is not without problems. In other words, in order to securely fix the flange portion attached to the connecting pin, both sides of the tip are in surface contact with both regulating walls of the locking member and the retaining plate is fixed to the locking member. It is necessary that the stop plate is in close contact with the surface of the collar portion. If there is a gap between the collar and the detent member, when the front work machine is operated, a force that rotates the collar around the connecting pin acts on the collar, and repeatedly collides with the detent member. It will be. Regardless of whether the machine operating conditions are such that a large load is not generated on the front work machine, an extremely large impact is applied when operating under severe conditions such as a crushed stone site. In the meantime, it occurs repeatedly, and the gap gradually expands over a long period of time, the degree of impact becomes larger and the anti-rotation member may eventually be damaged. Similarly, if there is even a slight gap between the collar portion and the retaining member, an impact is applied to the retaining member, and if this impact is repeated, the bolt loosens or deforms, etc. This will cause problems.

  From the above, in order to stably exert the detent and retaining functions of the connecting pin for a long period of time, the collar portion attached to the connecting pin is surely in surface contact with the detent member and the retaining member. In addition, each dimension must be strictly controlled, and their mounting position relationship must be strictly controlled.

  By the way, when assembling the front work machine, first, a steel plate is welded to form a can assembly structure that constitutes the boom and the arm, including pin hole machining that constitutes a connecting portion between the boom and the arm. Machining is a process after the welding process. That is, the welding process and the machining process are separate processes, and the welding process precedes the machining process. Since the anti-rotation member fixed to the boom or the like is also made by the welding means, it is common to weld the anti-rotation member as part of this welding process. And after this welding process, a pin hole is each drilled in the connection part of a boom and an arm at a machining process. Then, a connecting pin provided with a collar portion separately formed thereafter is inserted into this pin hole, and the retaining plate is fastened with a bolt.

  As described above, it is extremely difficult to accurately align the pin hole to be drilled thereafter with respect to the pre-welded anti-rotation member. Considering the case where it cannot be arranged between the regulating walls, the interval between the regulating walls tends to be slightly larger than the width dimension of the tip portion of the collar portion, and it is impossible to prevent a gap from being generated therebetween. The same applies to the contact surface between the retaining plate and the collar portion, and when the retaining plate is screwed to the non-rotating member, in order to ensure that a tightening force acts between them, rather than the collar portion. Generally, the thickness is slightly reduced so that a slight gap is formed between the collar portion and the retaining plate.

  In short, considering the manufacturing and assembly processes of the components of the front work machine, there is a problem that it is practically difficult to completely fix the collar portion attached to the connecting pin.

  The present invention has been made in view of the above points. The object of the present invention is to prevent the connection pin from rotating and retaining without affecting the process steps of welding, machining, and assembly of the connection pin. It is to make sure that the function is exhibited.

  In order to achieve the above-described object, the present invention constitutes a front working machine of a construction machine, two members that rotate relative to each other are connected by a connecting pin, and an end portion of the connecting pin is perpendicular to the axis thereof. A pin connecting structure in which a collar portion is connected and one of the two members is used as a base member, and the collar portion is fixed to the base member by means of detents and retaining means. A screw seat is mounted by welding means on both sides of the base member where the collar portion is disposed, and the collar portion is directed toward the base member side on the side facing the screw seat. An inclined side surface falling down is formed, and a stopper member having a tapered surface corresponding to the inclined side surface of the collar portion is fixed to the screw seat with a bolt.

  By bringing the tapered surface of the stopper member into contact with the tapered surface of the collar portion, a function to prevent the connecting pin from rotating and a function to prevent it from coming off are exhibited. However, since one stopper member exhibits a detent function only in one direction, the collar portion is mounted so as to be sandwiched between the stopper members from both sides. When the screw seats are welded in advance and the pin holes are drilled later by machining, they are assembled so that the tapered surface of the stopper member abuts against the inclined side surface of the collar even if there is a slight relative displacement between them. be able to.

  The load acting on the stopper member is preferably transmitted to a screw seat welded to the base member, and is supported on the base member via the screw seat. For this purpose, the stopper member and the screw seat have a contact surface formed in a direction substantially orthogonal to the surface of the base member. And the press-contact force of contact surfaces is obtained by the reaction force when the taper surface of a stopper member is press-contacted to the inclined side surface of a collar part.

  Here, when the screw seats are welded, the contact surfaces can be surely brought into surface contact with each other if the side surfaces thereof are parallel to the side surfaces of the flange portions to be mounted thereafter. That is, even if the interval between them slightly changes, the surface contact can be ensured. Furthermore, if the contact surface is formed so as to have a circular arc shape centered on the bolt, the parallelism between the side surface of the screw seat and the side surface of the collar portion is not required. When the tapered surface of the stopper member is brought into contact with the inclined side surface of the collar portion, the stopper member may be slightly lifted from the screw seat. Then, a bending load acts on the bolt, and a force in the direction in which the bolt loosens acts. In order to prevent such a situation, it is desirable that a shim is interposed between the stopper member and the screw seat so that no gap is generated therebetween.

  By configuring as described above, the collar portion attached to the connecting pin can be securely fixed, and the collar portion can be stably held even when the construction machine is operated in an extremely high load state. Accordingly, the wear and damage of the connecting pin can be prevented, and the effect of extending the life can be achieved.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. First, FIG. 1 shows an overall configuration of a hydraulic excavator as an example of a construction machine. In the figure, 1 is a lower traveling body and 2 is an upper turning body. The upper swing body 2 is provided with a front work machine 3 for performing work such as excavation of earth and sand, and accommodates equipment such as a cab 4 on which an operator for operating this machine, an engine, and a hydraulic pump are mounted. A building 5 or the like is installed on the upper swing body 2. The front work machine 3 includes a boom 3a that is mounted on the frame of the upper swing body 2 so as to be able to move up and down, an arm 3b that is pivotally connected to the tip of the boom 3a, and a link mechanism at the tip of the arm 3b. And a bucket 3c that is pivotally connected to perform excavation work such as earth and sand. The illustrated front work machine 3 is of a backhoe type, and other than this, it can be configured as a loader type front work machine.

  FIG. 2 shows a cross section of the connecting portion between the boom 3a and the arm 3b. The boom 3a and the arm 3b are connected to each other for relative rotation. For this purpose, a pair of connecting plate portions 10, 10 are provided at the tip of the boom 3 a, and the connecting portion 11 on the proximal end side of the arm 3 b is disposed at a position between these connecting plate portions 10, 10. The connection pins 12 are connected so as to be relatively rotatable. For this purpose, a pin insertion hole 13 is formed in the connecting portion 11, and a pin insertion hole 14 is formed in the connecting plate portions 10 and 10, so that the connecting pin 12 passes through these pin insertion holes 13 and 14. Will be attached to. In the figure, reference numeral 15 denotes a bush inserted through the pin insertion holes 13 and 14 in order to suppress wear of the connecting pin 12.

  In order to smoothly perform the relative rotation operation between the boom 3a and the arm 3b and suppress the wear of the connecting pin 12, the connecting pin 12 is fixedly held to the connecting plate portion 10 of the boom 3a. Thus, the connecting portion 11 of the arm 3b is rotatable around the axis of the connecting pin 12. That is, the connection pin 12 is prevented from rotating with respect to the connection plate portion 10 of the boom 3a. Further, the connecting pin 12 is restricted so as not to move in the axial direction, and exhibits a retaining function. Thus, the structure of the detent means and retaining means for the connecting pin 12 is shown in FIGS.

  As shown in FIGS. 3 and 4, the collar 16 is attached to one end of the connecting pin 12. The collar portion 16 is made of a metal plate, and is fixed to the end surface of the connecting pin 12 by means such as welding. The collar portion 16 projects from the portion fixed to the connecting pin 12 in one direction so as to be orthogonal to the axis of the connecting pin 12, and the width dimension continuously decreases as it goes toward the tip. It has become. In addition, as a shape of a collar part, you may have a uniform width dimension. The connecting pin 12 is mounted so as to penetrate from one pin insertion hole 14 to the other pin insertion hole 14 from the side opposite to the attachment side of the collar portion 16, and the collar portion 16 is attached to the surface of the connection plate portion 10. It is in contact. Accordingly, the connecting plate portion 10 with which the flange portion 16 is in contact serves as a base member.

  At both side edge portions of the flange portion 16, an inclined side surface 17 is formed by a predetermined length from the tapered tip to a predetermined position on the base end side, that is, toward the connecting portion side to the connecting pin 12. Yes. The inclined side surface 17 is inclined on both the left and right sides of the flange portion 16 so as to fall at a predetermined angle toward the contact portion with the connecting plate portion 10. Accordingly, the cross-sectional shape of the portion of the collar portion 16 where the inclined side surface 17 is formed is substantially trapezoidal.

  On the surface of the connecting plate part 10 constituting the base member, a pair of left and right screw seats 18 are fixed by welding means at positions on both sides of the collar 16 where the collar 16 is disposed. The screw seat 18 is preferably formed of a rectangular metal block having a thickness dimension higher than the thickness of the collar portion 16, and the side surface 18 a of the screw seat 18 is disposed at a predetermined position as shown in FIG. 5. At a position substantially parallel to the ridgeline of the inclined side surface 17. The screw seat 18 has a screw hole 19 into which a bolt 23 described later is screwed.

  A stopper member 20 is brought into contact with and fixed to each screw seat 18. The stopper member 20 is composed of a mounting portion 20a placed so as to be brought into contact with the surface of the screw seat 18 and an action portion 20b. The action portion 20b is formed with a tapered surface 21 having an inclination substantially matching the inclination angle of the inclined side surface 17 of the collar portion 16, and the tapered surface 21 is mounted so as to contact the inclined side surface 17 of the collar portion 16. It is what is done. Further, a contact surface 22 that contacts the side surface portion 18 a facing the collar portion 16 of the screw seat 18 is formed on the action portion 20 b. Therefore, the stopper member 20 is assembled such that the tapered surface 21 abuts on the inclined side surface 17 of the collar portion 16 and the abutting surface 22 abuts on the side surface 18 a of the screw seat 18.

  Although not shown, the mounting portion 20a of the stopper member 20 is provided with a bolt insertion hole. The mounting portion 20a is brought into contact with the surface of the screw seat 18 so that the bolt 23 is attached to the mounting portion 20a. The bolt insertion hole is penetrated and screwed into a screw hole 19 provided in the screw seat 18, whereby the stopper member 20 is fixed to the screw seat 18. The bolt insertion hole provided in the stopper member 20 allows the bolt 23 to be inserted in a loose fit.

  The detent means and the retaining means for the connecting pin 12 are configured as described above, and the boom 3a and the arm 3b constituting the front work machine 3 are each independently welded with a metal plate material to form a can assembly structure. To do. In this welding process, a bracket or the like for connecting the hydraulic cylinder is also attached. Further, since the screw seat 18 is fixed to the surface of the connecting plate portion 10 serving as a base member by welding, the screw seat 18 is also welded as part of the welding process. Here, the screw seat 18 does not necessarily require strict position adjustment, but when the collar portion 16 is assembled later, the side surface 18a is mounted at a position that is substantially parallel to the inclined side surfaces 17 on both the left and right sides of the collar portion 16. To do.

  Pin insertion holes 13 and 14 are formed in the boom 3a and the arm 3b, respectively, having a can assembly structure as described above. A pair of screw seats 18 is provided in the connecting plate portion 10 on the boom 3 a side, and a pin insertion hole 14 is formed in the connecting plate portion 10. When the pin insertion hole 14 is drilled, the position is adjusted so as to have a predetermined positional relationship with the screw seat 18. That is, when the connecting pin 12 is attached to the pin insertion hole 14 and the flange portion 16 fixed to the connecting pin 12 is brought into contact with the surface of the connecting plate portion 10, The formed inclined side surface 17 is adjusted so as to be substantially parallel to the screw seat 18.

  After the above-described machining is completed, the connecting pin 12 is assembled so that the boom 3a and the arm 3b are connected so as to be relatively rotatable. The flange portion 16 attached to the connecting pin 12 is disposed between a pair of left and right screw seats 18 and 18 fixed to the surface of the connecting plate portion 10 by welding means. Then, the stopper member 20 is attached to each screw seat 18. The stopper member 20 is formed with a tapered surface 21 that abuts on the flange portion 16 and an abutment surface 22 that abuts on the side surface of the screw seat 18 on the acting portion 20b, so that the stopper member 20 abuts on the side surface 18a of the screw seat 18. With the surface 22 in contact, the tapered surface 21 is brought into contact with the inclined side surface 17 of the collar portion 16, and the bolt 23 is screwed into the screw hole 19 of the screw seat 18 and fastened. As a result, the stopper member 20 is pressed toward the connecting plate portion 10, the tapered surfaces 21 of both stopper members 20 are pressed against the left and right inclined side surfaces 17 of the flange portion 16, and the abutting surface 22 is the screw seat 18. It will be in close contact with the side surface 18a.

  From the above, the inclined side surfaces 17 provided on the left and right sides of the collar portion 16 are sandwiched between the tapered surfaces 21 and 21 of both stopper members 20 and are pressed against the surface of the connecting plate portion 10. That is, the collar portion 16 is prevented from rotating and exhibits a retaining function. In addition, since the screw seat 18 is disposed substantially parallel to the side surface of the flange portion 16, the contact surface 22 of the stopper member 20 is pressed against the side surface 18a of the screw seat 18 by the fastening of the bolt 23, and the tapered surface. 21 and the inclined side surface 17 of the collar portion 16 are brought into close contact with each other. As a result, even when the work load during excavation of earth and sand by the front work machine 3 is extremely large, the load acting on the collar portion 16 is transmitted from the stopper member 20 via the screw seat 18 to the connecting plate portion. 10 is securely received and kept stationary during that time. In other words, the connecting pin 12 is reliably prevented from rotating and prevented from coming off, and an impact or the like due to the instability of the collar portion 16 does not act, thereby extending the life of the connecting pin preventing and retaining means. It is done.

  By the way, the tapered surface 21 of the stopper member 20 is in contact with the inclined side surface 17 of the flange portion 16, but the contact surface 22 is in contact with the screw seat 18. When the interval is narrow, the placement portion 20 a of the stopper member 20 is lifted from the surface of the screw seat 18. If so, the bolt 23 may loosen during operation of the hydraulic excavator. Therefore, as shown in FIG. 6, a shim 30 is mounted between the mounting portion 20 a of the stopper member 20 and the screw seat 18, and adjustment is performed so that no gap is generated between them, and a washer 31 prevents loosening. Should be done.

  Moreover, in embodiment mentioned above, it is requested | required that the screw seat 18 welded to the connection board part 10 should have a parallelism between the side surfaces of the collar part 16 when the connection pin 12 is mounted | worn. However, if the configuration shown in FIG. 7 is adopted, the screw seat may not be parallel to the collar portion. That is, in the screw seat 48 shown in FIG. 7, the side surface facing the collar portion 16 is an arc surface 48 a centering on the bolt 23. On the other hand, the contact surface 42 of the stopper member 40 has an arcuate surface shape having a curvature radius that matches the arc surface 48a of the screw seat 48. Accordingly, the stopper member 40 can be fixed even in a state where the tapered surface 41 is directed in an arbitrary direction. Accordingly, when the collar portion 16 is disposed between the screw seats 48 and 48 and the stopper member 40 is mounted, the tapered surface 41 is rotated along the circular arc surface 48 a described above, whereby the tapered surface 41 is inclined on the inclined side surface of the collar portion 16. 17 can be imitated.

1 is an overall configuration diagram of a hydraulic excavator as an example of a construction machine. It is sectional drawing of the connection part of the boom and arm which comprise a front work machine. It is a front view which shows the structure of the detent | locking of a connection pin, and a retaining member. It is sectional drawing in the XX position of FIG. It is the same front view as FIG. 3 which shows the state before mounting | wearing with a stopper member. It is an expanded sectional view which shows the state which adjusted the clearance gap produced between a screw seat and a stopper member. It is the same front view as FIG. 3 which shows the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Front work machine 3a Boom 3b Arm 10 Connection board part 11 Connection part 12 Connection pin 13, 14 Pin insertion hole 16 Collar part 17 Inclined side surface 18, 48 Screw seat 19, 49 Screw hole 20, 40 Stopper member 21, 41 Tapered surface 22 Contact surface 23 Bolt 48a Arc surface

Claims (4)

A front working machine of a construction machine is configured, and two members that rotate relative to each other are connected by a connecting pin, and a flange portion is connected to an end of the connecting pin in a direction perpendicular to the axis thereof. In the pin connection structure in which either one of the members is a base member and the collar portion is fixed to the base member by a detent and retaining means,
Attach screw seats by welding means at positions on both sides of the base member where the collar portion is disposed;
In the collar portion, an inclined side surface that falls toward the base member side is formed on a side portion facing the screw seat,
A pin connection structure characterized in that a stopper member having a tapered surface corresponding to the inclined side surface of the collar portion is fixed to the screw seat with a bolt. 2. The pin connection structure according to claim 1, wherein the stopper member and the screw seat have a contact surface formed in a direction substantially orthogonal to the surface of the base member. The pin connection structure according to claim 2, wherein the contact surface has a circular arc shape centered on the bolt. 4. The pin connection structure according to claim 2, wherein the stopper member is configured to be bolted in a state in which the height can be adjusted by a shim with respect to the screw seat.

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