JP2007231579A - Front device of construction machinery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance durability and workability by preventing the deformation of upper and lower flanges of a working arm without an increase in the weight of a pin connecting part. <P>SOLUTION: Right and left brackets 20 and 19 of the pin connecting part 18 are erected on the extensions of the right and left webs 12D and 12C of a boom 12, respectively. Right and left stepped bosses 25 and 21 are mounted on the right and left brackets 20 and 19 in such a manner as to face them on the same axis, respectively, so that a mounting eye 16A of an arm cylinder 16 can be sandwiched between the respective stepped bosses 25 and 21 without making the respective brackets 20 and 19 thick-walled. Additionally, a step part 24 for making a flange part 28B of the connecting pin 28 intrude up to a back part is provided in the left stepped boss 21, so that the connecting pin 28 is formed in a short shape. This can prevent the deformation of the upper flange 12A of the boom 12 without the increase of the weight, and increase the workability of the front device 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a front device for a construction machine that performs work by, for example, expansion and contraction of a hydraulic cylinder.

  Generally, a front device mounted on a hydraulic excavator as a construction machine includes a boom attached to the front side of a revolving frame so as to be able to be lifted and lowered, an arm attached to the tip side of the boom to be able to be raised and lowered, A bucket rotatably attached to the distal end side, a boom cylinder provided between the revolving frame and the boom for raising and lowering the boom, the boom and the boom for raising and lowering the arm It is roughly constituted by an arm cylinder provided between the arm and a bucket cylinder provided between the arm and the bucket for rotating the bucket.

  Further, the boom and the arm of the front device are formed as a box structure having a square cross section with a hollow inside in order to be lightweight while maintaining high strength. That is, for example, the boom includes a rectangular tube-like working arm in which a left web and a right web arranged in parallel are sandwiched from above and below by an upper flange and a lower flange, and each member is fixed by welding means, and the working arm. A pin coupling portion provided on the lower flange for rotatably supporting the mounting eye of the boom cylinder and a pin coupling portion provided on the upper flange of the working arm for rotatably supporting the mounting eye of the arm cylinder. It is configured.

  In addition, each pin coupling portion is provided with a pair of brackets standing in parallel on the lower surface of the lower flange and the upper surface of the upper flange, spaced apart in the left and right directions, and having pin holes on the same axis, and the pins of the brackets The connecting pin is inserted into the hole and rotatably supports the mounting eye of the cylinder.

  Here, since the pin coupling portion attached to the work arm supports the cylinder that drives the front device, a large load is applied to the pin coupling portion due to hydraulic pressure or reaction force during excavation. Therefore, if the mounting position of each web and each bracket with respect to the lower flange and the upper flange is separated, the lower flange and the upper flange may be deformed between the web and the bracket. There is a risk of damage to the welded portion with the web.

  Therefore, in the prior art, the left bracket and the right bracket of the pin coupling portion are erected on the left and right positions of the lower flange and the upper flange so as to be on the extension of the left web and right web of the work arm. There is a configuration that prevents the deformation of the lower flange and the upper flange (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 58-63254

  By the way, in the prior art according to Patent Document 1 described above, in order to dispose the left bracket and the right bracket of the pin coupling portion on the extension of the left web and the right web of the work arm, the brackets are greatly separated in the left and right directions. I am letting. For this reason, the left bracket and the right bracket are formed thick so that the mounting eye of the cylinder can be sandwiched. Further, the connecting pin needs to be formed longer by the distance between the left bracket and the right bracket. Thereby, since the weight of a pin coupling part increases, there exists a problem that workability | operativity etc. of a front apparatus fall.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to prevent the upper and lower flanges of the work arm from being deformed without increasing the weight of the pin coupling portion. Another object of the present invention is to provide a construction machine front device capable of improving workability.

  A front device of a construction machine according to the present invention is provided on a work arm formed in a box structure by welding an upper flange, a lower flange, a left web and a right web, and an upper flange and / or a lower flange of the work arm. And a pin coupling portion that rotatably supports the mounting eye of the hydraulic cylinder using a connecting pin.

  In order to solve the above-described problem, the feature of the configuration adopted by the invention of claim 1 is that the pin coupling portion is positioned on an extension of the left web and the right web of the working arm, and an upper flange and And / or a pair of brackets erected on the left and right positions of the lower flange, and a pair of bosses respectively attached to the brackets so as to face each other on the same axis, and at least of the bosses One boss is formed as a stepped boss in which the inner diameter on the bracket side is large and the inner diameter on the mounting eye side is small.

  According to the invention of claim 2, the connecting pin is formed shorter than the length dimension between the pair of brackets.

  According to the invention of claim 3, the stepped boss is formed by welding a bracket side boss and a mounting eye side boss on the same axis.

  According to a fourth aspect of the present invention, the connecting pin has a flange portion that contacts the step portion of the stepped boss on one side in the axial direction, and a pin insertion hole through which the retaining pin is inserted on the other side in the axial direction. The configuration has the following.

  According to the first aspect of the present invention, the left bracket and the right bracket of the pin coupling portion stand on the left and right positions of the upper flange and / or the lower flange so as to be positioned on the extension of the left web and the right web of the work arm. For example, the load when the cylinder is driven can be directly transmitted from each bracket of the pin coupling portion to each web of the work arm, and deformation of the upper flange and the lower flange can be prevented. .

  Further, since the bosses are attached to the brackets so as to face each other on the same axis, the mounting eyes of the hydraulic cylinder can be sandwiched by the bosses without forming the brackets thickly. In addition, at least one of the bosses is formed as a stepped boss having a large inner diameter on the bracket side and a smaller inner diameter on the mounting eye side. It is possible to make the buttocks approach to the back, and the connecting pin can be formed short.

  As a result, in the pin coupling portion, each bracket can be formed thin and the connecting pin can be formed short, so that deformation of the upper flange and lower flange of the work arm can be prevented without increasing the weight, and the workability of the front device can be reduced. Improvement, reduction of manufacturing cost, etc. can be aimed at.

  According to the invention of claim 2, since the connecting pin is formed shorter than the length dimension between the brackets, the weight of the connecting pin can be reduced, and the handleability at the time of attachment / detachment can be improved.

  According to the invention of claim 3, the stepped boss can be easily formed by welding the bracket-side boss and the mounting eye-side boss on the same axis, thereby improving the assembly workability and reducing the manufacturing cost. Can be planned. Also, by preparing bracket-side bosses and mounting eye-side bosses with different diameters, etc., these can be freely combined, so they are used as general-purpose parts for multiple types of pin coupling parts with different shapes, sizes, etc. be able to.

  According to the invention of claim 4, when the connecting pin is inserted into the stepped boss, the hook part can be advanced to the back side to the bracket side having a large diameter. The length dimension can be shortened. Further, by inserting the retaining pin through the pin insertion hole when the coupling pin is inserted into each boss, the coupling pin can be retained against the other boss and prevented from rotating. In this case, the connecting pin does not need to pass through the left and right bosses, and therefore can be further shortened.

  Hereinafter, as a front device of a construction machine applied to an embodiment of the present invention, a front device of a hydraulic excavator will be described as an example and described in detail with reference to the accompanying drawings.

  1 to 5 show a first embodiment of the present invention. In the first embodiment, a boom of the front device will be described as an example of the working arm of the front device.

  In FIG. 1, reference numeral 1 denotes a hydraulic excavator as a construction machine. The hydraulic excavator 1 includes a self-propelled lower traveling body 2, an upper revolving body 3 that is rotatably mounted on the lower traveling body 2, It is generally configured by a front device 11 (described later) provided on the front side of the upper swing body 3. Here, the upper revolving structure 3 includes a revolving frame 4, a cab 5 mounted on the left front side of the revolving frame 4, a counterweight 6 attached to the rear portion of the revolving frame 4, and the like. .

  Next, reference numeral 11 denotes a front device according to the first embodiment provided on the front side of the upper swing body 3. The front device 11 performs excavation work of earth and sand. The front device 11 is roughly constituted by a boom 12, an arm 13, a bucket 14, a boom cylinder 15, an arm cylinder 16, a bucket cylinder 17, a pin coupling portion 18 and the like which will be described later.

  Reference numeral 12 denotes a boom whose base end is attached to the front side of the revolving frame 4 so as to be able to move up and down. The boom 12 constitutes the working arm of the front device 11, and as shown in FIGS. 2 and 3, the inside is hollow and the cross section is square by the upper flange 12A, the lower flange 12B, the left web 12C and the right web 12D. It is formed as a box structure having a shape. In other words, the boom 12 has the left web 12C and the right web 12D arranged in parallel to each other, and the upper flange 12A and the lower web 12D are arranged so as to sandwich the left web 12C and the right web 12D from above and below. The flange 12B is disposed. In this state, the contact portion between the members is fixed by welding means to form a square cylinder.

  A boom cylinder mounting portion 12E (only the left side is shown) to which a rod 15B tip of a boom cylinder 15 (to be described later) is mounted is provided at the intermediate portion in the length direction of the left and right webs 12C and 12D. Further, a pin coupling portion 18 for an arm cylinder 16 to be described later is attached to the upper side of the upper flange 12A.

  Reference numeral 13 denotes an arm attached to the tip of the boom 12 so as to be able to move up and down (illustrated in FIG. 1). The arm 13 constitutes a working arm like the boom 12 and is formed as a box structure having a square cross section. Further, on the proximal end side of the arm 13, a pin coupling portion 13A for rotatably supporting a tube 17A proximal end of a bucket cylinder 17 described later and a pin coupling portion 13B to which a rod 16C distal end of an arm cylinder 16 described later is attached. And are provided.

  Reference numeral 14 denotes a bucket that is rotatably attached to the tip of the arm 13. The bucket 14 is connected to the tip of the rod 17B of the bucket cylinder 17 via a link mechanism 14A.

  Reference numeral 15 denotes two boom cylinders (only the left side is shown) provided between the revolving frame 4 and the boom 12, and each boom cylinder 15 moves the boom 12 up and down. The boom cylinder 15 has a tube 15A base end rotatably attached to the front end of the revolving frame 4 and a rod 15B tip attached to the boom cylinder attachment portion 12E of the boom 12 so as to be rotatable.

  Reference numeral 16 denotes one arm cylinder provided between the boom 12 and the arm 13, and the arm cylinder 16 moves the arm 13 up and down with respect to the boom 12. Further, as shown in FIG. 2, the arm cylinder 16 is roughly constituted by a tube 16B having a base end portion serving as a mounting eye 16A and a rod 16C projecting from the distal end side of the tube 16B so as to be extendable and contractible. The arm cylinder 16 has a mounting eye 16 </ b> A rotatably attached to a pin coupling portion 18 described later provided on the boom 12, and a rod 16 </ b> C tip is pivotally attached to a pin coupling portion 13 </ b> B of the arm 13. Yes.

  Reference numeral 17 denotes one bucket cylinder provided between the arm 13 and the bucket 14. The bucket cylinder 17 rotates the bucket 14 at the tip of the arm 13. Further, the bucket cylinder 17 has a tube 17 </ b> A having a base end rotatably attached to the pin coupling portion 13 </ b> A of the arm 13 and a rod 17 </ b> B tip attached to the link mechanism 14 </ b> A of the bucket 14.

  Next, 18 indicates a pin coupling portion for the arm cylinder 16 according to the first embodiment provided on the outer surface of the upper flange 12A of the boom 12. As shown in FIG. 2, the pin coupling portion 18 supports the mounting eye 16 </ b> A of the arm cylinder 16 so as to be rotatable toward the boom 12. As shown in FIGS. 3 and 4, the pin coupling portion 18 is roughly constituted by a left bracket 19, a right bracket 20, a left stepped boss 21, a right stepped boss 25, a connecting pin 28, a retaining pin 29 and the like which will be described later. It is configured.

  Reference numeral 19 denotes a left bracket made of a substantially triangular plate mounted on the upper flange 12A of the boom 12. When the left web 12C is extended upward, the left bracket 19 is positioned above the extension. It is erected on the left position of the flange 12A. By attaching the left bracket 19 to this position, even if a load (stress) is applied to the left bracket 19, it is possible to prevent the upper flange 12A from being deformed by this load. Further, as shown in FIG. 5, the left bracket 19 is provided with an attachment hole 19A for attaching a left stepped boss 21 described later.

  Reference numeral 20 denotes a right bracket made of a substantially triangular plate body mounted on the upper flange 12A of the boom 12 so as to make a pair with the left bracket 19. The right bracket 20 is erected at the right position of the upper flange 12A so as to be positioned on the extension when the right web 12D is extended upward. Thereby, even when a load (stress) is applied, the right bracket 20 can prevent the upper flange 12 </ b> A from being deformed by this load, similarly to the left bracket 19. Further, the right bracket 20 is provided with a mounting hole 20A for mounting a right stepped boss 25 described later.

  Reference numeral 21 denotes a left stepped boss attached to the left bracket 19. The left stepped boss 21 is inserted into the attachment hole 19A so as to protrude toward the right bracket 20 side. Further, as shown in FIG. 4, the left stepped boss 21 constitutes a boss on one side into which a connecting pin 28 described later is inserted first. Further, as shown in FIG. 5, the left stepped boss 21 includes a bracket side boss 22 having a larger diameter hole 22 </ b> A located on the left bracket 19 side and larger than the flange portion 28 </ b> B of the connecting pin 28, and the arm cylinder 16. It is composed of two members, the mounting eye 16A, and a mounting eye side boss 23 having a small diameter hole 23A into which the pin main body 28A of the connecting pin 28 is inserted.

  The left stepped boss 21 is formed as one boss by abutting the bracket-side boss 22 and the mounting eye-side boss 23 on the same axis and performing, for example, laser welding on the abutting portion. The left stepped boss 21 is, for example, between the mounting hole 19A of the left bracket 19 and the outer periphery of the bracket side boss 22 with the end of the bracket side boss 22 inserted into the mounting hole 19A of the left bracket 19. It is integrally fixed to the left bracket 19 by performing laser welding.

  Thus, a stepped portion 24 is formed in the left stepped boss 21 by the large diameter hole 22 </ b> A of the bracket side boss 22 and the end surface 23 </ b> B of the mounting eye side boss 23. The step portion 24 is formed with a larger diameter than a flange portion 28B of the connecting pin 28 described later. Then, the step portion 24, when the connecting pin 28 is inserted into the left stepped boss 21, can cause the flange portion 28B to enter the back position where the end portion 23B comes into contact with the end surface 23B. The length dimension can be shortened.

  On the other hand, 25 is a right stepped boss attached to the right bracket 20, and the right stepped boss 25 protrudes toward the left bracket 19 so as to face each other on the same axis as the left stepped boss 21. It is inserted into the mounting hole 20A. Further, the right stepped boss 25 includes, for example, a bracket side boss 26 having a large diameter hole 26A located on the right bracket 20 side and a mounting eye 16A of the arm cylinder 16 in order to share parts with the left stepped boss 21. The mounting eye side boss 27 includes a small-diameter hole 27A into which the pin main body 28A of the connecting pin 28 is inserted. Further, a pin insertion hole 26B is formed in the bracket-side boss 26 so as to penetrate in the diameter direction, and a retaining pin 29 described later is inserted into the pin insertion hole 26B.

  The right stepped boss 25, like the left stepped boss 21, has a bracket-side boss 26 and a mounting eye-side boss 27 butted on the same axis, and laser welding is performed on the butted portion, for example. It is formed as. Further, the right stepped boss 25 is between the mounting hole 20A of the right bracket 20 and the outer periphery of the bracket side boss 26 in a state where the end of the bracket side boss 26 is inserted into the mounting hole 20A of the right bracket 20. For example, it is integrally fixed to the right bracket 20 by performing laser welding.

  Reference numeral 28 denotes a connecting pin which is inserted from the left stepped boss 21 to the right stepped boss 25 and rotatably supports the mounting eye 16A of the arm cylinder 16. The connecting pin 28 is roughly constituted by a cylindrical pin main body 28A and a retaining collar 28B provided by expanding the base end portion of the pin main body 28A. In addition, a pin insertion hole 28C is provided in the diameter direction in the distal end side of the pin main body 28A.

  The connecting pin 28 is inserted into the left stepped boss 21 at the tip side where the pin insertion hole 28C is provided, and sequentially inserted into the mounting eye 16A of the arm cylinder 16 and the right stepped boss 25, whereby the arm cylinder The 16 tubes 16B can be rotatably supported.

  Here, the connecting pin 28 can have its flange portion 28 </ b> B enter the back portion of the left stepped boss 21 by the step portion 24. Further, it is possible to prevent the distal end portion from protruding without protruding from the right stepped boss 25. Thereby, as shown in FIG. 3, the length dimension L of the connecting pin 28 can be formed shorter than the length dimension W between the left bracket 19 and the right bracket 20.

  Reference numeral 29 denotes a retaining pin provided between the right stepped boss 25 and the connecting pin 28. The retaining pin 29 is formed as a long bolt exceeding the diameter dimension of the right stepped boss 25. The retaining pin 29 is inserted into the pin insertion hole 26 </ b> B of the bracket-side boss 26 and the pin insertion hole 28 </ b> C of the connection pin 28 in a state where the connection pin 28 is inserted up to the right stepped boss 25. By screwing 29A, the connecting pin 28 can be prevented from being pulled out and prevented from rotating.

  The front device 11 of the hydraulic excavator 1 applied to the first embodiment has the above-described configuration. Next, the arm cylinder 16 is attached to the pin coupling portion 18 of the boom 12 which is a characteristic part of the present invention. The installation work will be described.

  First, the mounting eye 16A of the arm cylinder 16 is arranged so as to be coaxial between the left stepped boss 21 and the right stepped boss 25, and in this state, the connecting pin 28 is connected to the left stepped boss 21, the mounting eye 16A, Insert the right stepped bosses 25 in this order. At this time, the connecting pin 28 can allow the retaining collar 28B to enter the back of the step 24 in the left stepped boss 21. Can be inserted into. When the connecting pin 28 is inserted until the collar portion 28B contacts the end face 23B of the mounting eye boss 23, the retaining pin 29 is inserted into the right stepped boss 25 and the connecting pin 28, thereby connecting the connecting pin 28. To prevent it from rotating.

  Next, the operation of the hydraulic excavator 1 will be described. The operator can travel the lower traveling body 2 by, for example, operating the traveling operation lever and pedal among various operation levers and pedals (none of which are shown) by getting on the cab 5. Further, by operating the operation lever for work, the front device 11 and the like can be moved up and down to perform, for example, excavation work of earth and sand.

  Here, when excavation work or the like is performed with the front device 11, for example, a load such as an oil pressure when the arm 13 is moved up and down by the arm cylinder 16, a reaction force during excavation, or the like is transmitted via the pin coupling portion 18. It is transmitted to. However, in the first embodiment, the left bracket 19 and the right bracket 20 of the pin coupling portion 18 are erected on the extension of the left web 12C and the right web 12D of the boom 12, so that the load at this time is applied. This can be transmitted directly to the left web 12C and the right web 12D of the boom 12, and the deformation of the upper flange 12A can be prevented.

  As described above, according to the first embodiment, the left bracket 19 and the right bracket 20 of the pin coupling portion 18 are erected on the extensions of the left web 12C and the right web 12D of the boom 12. Therefore, the load generated during work can be directly transmitted from the left bracket 19 and the right bracket 20 to the left web 12C and the right web 12D of the boom 12. As a result, the mounting strength of the left bracket 19 and the right bracket 20 can be increased, and damage to the welded part due to the deformation of the upper flange 12A can be prevented. Etc. can be improved.

  On the other hand, in the first embodiment, the left stepped boss 21 and the right stepped boss 25 are attached to the left bracket 19 and the right bracket 20 so as to face each other on the same axis. Can be supported with the stepped bosses 21 and 25 sandwiching the mounting eye 16A of the arm cylinder 16 without forming them thick.

  In addition, the side where the connecting pin 28 is first inserted, that is, the left stepped boss 21 where the flange 28B is disposed, is formed by the large-diameter hole 22A of the bracket-side boss 22 and the end face 23B of the mounting eye-side boss 23. Since the step portion 24 having a diameter larger than that of the flange portion 28B is provided, the flange portion 28B of the connecting pin 28 can be advanced to the back. As a result, the connecting pin 28 has the length L between the left bracket 19 and the right bracket 20 in spite of the left bracket 19 and the right bracket 20 being separated in the left and right directions. It can be formed shorter than W.

  As a result, the pin coupling portion 18 can form the left bracket 19 and the right bracket 20 thin, and can also form the connecting pin 28 short, so that the top of the boom 12 is not increased without increasing the weight. The deformation of the flange 12A can be prevented, and the workability of the front device 11 can be improved and the manufacturing cost can be reduced. In addition, since the connecting pin 28 is formed short, the weight of the connecting pin 28 can be reduced and the handleability at the time of attachment / detachment can be improved.

  The left stepped boss 21 can be easily formed by welding the bracket side boss 22 and the mounting eye side boss 23 on the same axis. Moreover, since the large-diameter hole 22A is provided in the bracket-side boss 22 and the small-diameter hole 23A is provided in the mounting eye-side boss 23, the large-diameter hole 22A of the bracket-side boss 22 and the end surface 23B of the mounting-eye-side boss 23 In addition, the step portion 24 that accommodates the flange portion 28B of the connecting pin 28 can be easily formed without performing a separate cutting process or the like. As a result, it is possible to reduce the processing man-hours and manufacturing costs for manufacturing the left stepped boss 21 and the like.

  On the other hand, a retaining pin 29 is provided between the right stepped boss 25 and the connecting pin 28 to prevent the connecting pin 28 from coming off and to prevent the connecting pin 28 from rotating. It is not necessary to form long until it penetrates the boss 25, and it can be formed short.

  Furthermore, since the bracket side boss 22 and the mounting eye side boss 23 can be freely combined, they can be used as general-purpose parts in a plurality of types of pin coupling portions having different shapes, sizes, and the like.

  Next, FIG. 6 shows a second embodiment according to the present invention. The feature of this embodiment is that a left stepped boss is formed by two cylindrical bodies having different diameter dimensions. The construction is such that the left bracket is fixed by fillet welding. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 6, reference numeral 31 denotes a left stepped boss according to the second embodiment attached to the left bracket 19. This left stepped boss 31 is inserted into a large-diameter bracket-side boss 32 having a large-diameter hole 32A larger than the flange portion 28B of the connection pin 28, and a large-diameter hole 32A of the bracket-side boss 32. It is composed of two members, a small-diameter mounting eye side boss 33 having a small-diameter hole 33A into which 28 pin main bodies 28A are inserted.

  The left stepped boss 31 has the mounting eye-side boss 33 inserted into the large-diameter hole 32A of the bracket-side boss 32 by a predetermined dimension. In this state, for example, between the bracket-side boss 32 and the mounting eye-side boss 33, It is formed as one boss by performing fillet welding by arc welding. The left stepped boss 31 is inserted deeply into the mounting hole 19A until the bracket-side boss 32 protrudes from the left bracket 19, and in this state, the mounting hole 19A of the left bracket 19 and the outer periphery of the bracket-side boss 22 Both corners are integrally fixed to the left bracket 19 by performing fillet welding by arc welding, for example.

  Reference numeral 34 denotes a step portion according to the second embodiment formed by the large-diameter hole 32A of the bracket-side boss 32 and the end surface 33B of the mounting eye-side boss 33.

  Thus, also in the second embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment. In particular, in the second embodiment, the bracket-side boss 32 and the mounting eye-side boss 33 of the left stepped boss 31 have an insertion structure. Positioning work can be easily performed.

  Next, FIG. 7 shows a third embodiment according to the present invention. The feature of this embodiment is that a front device arm is used as a working arm of the front device, and a pin coupling portion is provided on this arm. There is. In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 7, reference numeral 41 denotes an arm as a working arm according to the third embodiment. This arm 41 is substantially the same as the boom 12 according to the first embodiment, and has an upper flange 41A, a lower flange 41B, a left web 41C and a right web (not shown). It is formed as a box structure.

  Reference numeral 42 denotes a pin coupling portion for the bucket cylinder 17 according to the third embodiment provided on the outer surface of the upper flange 41A of the arm 41. The pin coupling portion 42 is substantially the same as the pin coupling portion 18 for the arm cylinder 16 according to the first embodiment, and includes a left bracket 43, a right bracket 44, a left step boss 45, a right step boss 46, and a connecting pin. 47 and the like.

  Thus, also in the third embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the respective embodiments. In particular, according to the third embodiment, the pin coupling portion 42 according to the present invention can be provided to the arm 41 as well.

  Next, FIG. 8 shows a fourth embodiment according to the present invention. The feature of this embodiment is that a pin coupling portion according to the present invention is provided on both the upper flange and the lower flange of the boom. . In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 8, reference numeral 51 denotes a boom as a working arm according to the fourth embodiment. The boom 51 is substantially the same as the boom 12 according to the first embodiment. The upper flange 51A, the lower flange 51B, the left web 51C, and the right web (not shown) are hollow and the cross section is rectangular. It is formed as a box structure. The boom 51 is used for a small hydraulic excavator called a mini excavator. The lower flange 51B is provided with a later-described pin coupling portion 52 for attaching one boom cylinder (not shown), and the upper flange 51A has 1 A pin coupling portion 53 (described later) for attaching a book arm cylinder (not shown) is provided.

  Reference numeral 52 denotes a boom cylinder pin coupling portion according to the fourth embodiment provided on the lower surface of the lower flange 51B of the boom 51. Reference numeral 53 denotes a pin coupling portion for an arm cylinder according to the fourth embodiment provided on the upper surface of the upper flange 51A of the boom 51. These pin coupling portions 52 and 53 are configured in substantially the same manner as the pin coupling portion 18 for the arm cylinder 16 according to the first embodiment.

  Thus, also in the fourth embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the respective embodiments. In particular, according to the fourth embodiment, the boom 51 can be provided with the pin coupling portion 52 for the boom cylinder and the pin coupling portion 53 for the arm cylinder according to the present invention. Can be achieved.

  In the first embodiment, the left stepped boss 21 has the mounting hole 19A of the left bracket 19 and the bracket side boss 21 in a state where the end of the bracket side boss 22 is inserted into the mounting hole 19A of the left bracket 19. The case where it is configured to be integrally fixed to the left bracket 19 by performing, for example, laser welding between the outer periphery of 22 has been described as an example.

  However, the present invention is not limited to this. For example, as in the first modification shown in FIG. 9, the end of the bracket side boss 62 of the left stepped boss 61 is inserted into the mounting hole 19 </ b> A of the left bracket 19. The left stepped boss 61 may be integrally fixed to the left bracket 19 by performing fillet welding by arc welding, for example, at the corners of the inner surface of the left bracket 19 and the outer periphery of the bracket side boss 62. .

  Further, as in the second modification shown in FIG. 10, the mounting hole 19 </ b> A and the bracket-side boss 71 are fitted with the end of the bracket-side boss 72 of the left stepped boss 71 inserted into the mounting hole 19 </ b> A of the left bracket 19. For example, laser welding is performed between the outer periphery of the left bracket 19, and fillet welding by, for example, arc welding is performed on the corners between the inner surface of the left bracket 19 and the outer periphery of the bracket-side boss 72. It is good also as a structure which fixes the boss | hub 71 integrally.

  Further, as in the third modified example shown in FIG. 11, in the state where the end surface of the bracket side boss 82 of the left stepped boss 81 is in contact with the periphery of the mounting hole 19 </ b> A of the left bracket 19, The left stepped boss 81 may be integrally fixed to the left bracket 19 by performing fillet welding by arc welding, for example, at the corner between the side surface and the outer periphery of the bracket side boss 82.

  On the other hand, in the first embodiment, the left stepped boss 21 has a single stepped portion by abutting the bracket side boss 22 and the mounting eye side boss 23 on the same axis and applying, for example, laser welding to the abutting portion. The case where it is formed as an attached boss has been described as an example. However, the present invention is not limited to this. For example, the left boss 91 according to the fourth modification shown in FIG. 12 is attached to the bracket-side boss 92 having a different outer diameter within the thickness range. The eye-side boss 93 may be abutted on the same axis, and fillet welding by arc welding may be performed on the stepped portion (corner corner).

  Further, as in the fifth modification shown in FIG. 13, the left stepped boss 101 may be configured by providing a large diameter hole 101A and a small diameter hole 101B in a single cylindrical body (pipe member).

  Further, in the first embodiment, the case where the right stepped boss 25 is configured to weld the bracket side boss 26 and the mounting eye side boss 27 as in the case of the left stepped boss 21 is illustrated. However, the present invention is not limited to this, and the right boss 111 may be configured by a single cylindrical body without a stepped portion, for example, as in a sixth modification shown in FIG.

  Here, the first to sixth modifications described above can be similarly applied to the right stepped boss of the pin coupling portion. The first to sixth modifications can be applied to other embodiments in the same manner.

1 is an external perspective view showing a hydraulic excavator provided with a front device according to a first embodiment of the present invention. It is an external appearance perspective view which expands and shows the boom in FIG. 1, an arm cylinder, and a pin coupling part. It is the expanded sectional view which looked at the boom, the arm cylinder, and the pin coupling | bond part from the arrow III-III direction in FIG. It is an exploded sectional view showing an arm cylinder and a pin coupling part in an exploded manner. It is an expanded disassembled sectional view which decomposes | disassembles and shows a left bracket and a left stepped boss. It is an expanded sectional view shown in the state where the left stepped boss by the 2nd embodiment of the present invention was attached to the left bracket. It is an external appearance perspective view shown in the state which provided the pin coupling part by the 3rd Embodiment of this invention in the arm. It is an external appearance perspective view which shows the pin coupling part by the 4th Embodiment of this invention in the state provided in the boom of a small hydraulic shovel. It is a principal part expanded sectional view which shows the attachment state of the left bracket by the 1st modification of this invention, and the left stepped boss | hub. It is a principal part expanded sectional view which shows the attachment state of the left bracket and left step boss | hub by the 2nd modification of this invention. It is a principal part expanded sectional view which shows the attachment state of the left bracket and left step boss | hub by the 3rd modification of this invention. It is an expanded sectional view showing the left stepped boss by the 4th modification of the present invention. It is an expanded sectional view showing the left stepped boss by the 5th modification of the present invention. It is an expanded sectional view which shows the pin coupling part provided with the right boss | hub by the 6th modification of this invention.

Explanation of symbols

1 Excavator (construction machine)
11 Front device 12, 51 Boom (working arm)
12A, 41A, 51A Upper flange 12B, 41B, 51B Lower flange 12C, 41C, 51C Left web 12D Right web 13, 41 Arm (working arm)
14 Bucket 15 Boom cylinder 16 Arm cylinder 16A Mounting eye 17 Bucket cylinder 18, 42, 52, 53 Pin joint 19, 43 Left bracket 19A, 20A Mounting hole 20, 44 Right bracket 21, 31, 45, 61, 71, 81 , 91, 101 Left stepped boss 22, 32, 62, 72, 82, 92 Bracket side boss 22A, 32A, 101A Large diameter hole 23, 33, 93 Mounting eye side boss 23A, 33A, 101B Small diameter hole 23B, 33B End face 24,34 Stepped portion 25,46 Right stepped boss 28,47 Connecting pin 28A Pin body 28B Hook 28C Pin insertion hole 29 Retaining pin 111 Right boss L Length of connecting pin W Between left bracket and right bracket Length dimension

Claims (4)

A work arm formed into a box structure by welding the upper flange, the lower flange, the left web, and the right web, and a connecting pin for the mounting eye of the hydraulic cylinder provided on the upper flange and / or the lower flange of the work arm In a front device of a construction machine comprising a pin coupling portion that is rotatably supported.
The pin coupling portion includes a pair of brackets erected on the left and right positions of the upper flange and / or the lower flange so as to be located on the extension of the left web and right web of the working arm, and is identical to each bracket. It is composed of a pair of bosses attached to face each other on the axis,
At least one of the bosses is formed as a stepped boss having a large inner diameter on the bracket side and a smaller inner diameter on the mounting eye side.   The front device for a construction machine according to claim 1, wherein the connecting pin is formed shorter than a length dimension between the pair of brackets.   The construction machine front device according to claim 1, wherein the stepped boss is formed by welding a bracket side boss and a mounting eye side boss on the same axis. 2. The connecting pin has a configuration in which an axial portion is provided with a flange portion that comes into contact with a step portion of the stepped boss, and a pin insertion hole through which a retaining pin is inserted on the other side in the axial direction. , 2 or 3 Construction equipment front device.

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