JP2010163822A - Boom for working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify repair work for mutually abutting portions in boom connection regarding a boom for a working machine. <P>SOLUTION: A side plate at one end side of a main boom is protrusively provided with a scoop-up pin in a horizontal direction, and an intermediate boom 8 is connected in a non-turnabe manner to the main boom by a boom connecting pin 9. The intermediate boom 8 is provided with a hook 21 corresponding to the scoop-up pin. When the main boom and the intermediate boom 8 are connected, the intermediate boom 8 and the main boom are relatively turned around the scoop-up pin in the mutually abutting state of the scoop-up pin and the hook 21 to align the boom connecting pin 9. The surface abutting on the scoop-up pin of the hook 21 is provided with a removable replacement plate 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a boom of a work machine, and particularly relates to improvement of durability with respect to a joint structure between constituent booms.

  2. Description of the Related Art Conventionally, there is a boom of a work machine configured such that a boom length can be changed by adding a plurality of constituent booms so as not to rotate. This type of boom includes a first boom having a scooping pin projecting in a horizontal direction on a side plate on one end side, and a second boom that is non-rotatably coupled to the first boom by a boom connecting pin. The second boom is provided with a hook corresponding to the scooping pin, and when the first boom and the second boom are connected, the scooping pin and the hook are in contact with each other. In addition, the second boom and the first boom are relatively rotated to facilitate the alignment of the boom connecting pin.

For example, in Patent Document 1, a scooping pin for an intermediate boom (first boom) is brought into contact with a hook provided at the tip of a lower boom (second boom), and the intermediate boom is scooped up with the scooping pin as a center. It is moved to align the connecting pins.
Utility Model Registration Gazette No. 2535667

  However, in the boom of a conventional work machine, the scooping pin and the hook are worn by rubbing each time the constituent boom is changed. If repeated several times, the dimensional accuracy is lost, and the boom connecting pin cannot be aligned. Then, it is necessary to repair rake pins or hooks to maintain dimensional accuracy, but these are usually welded directly to the side plate of the boom, so it is extremely difficult to re-weld the parts to be replaced after cutting them from the boom. It is complicated. Furthermore, after exchanging parts to be exchanged, it may be necessary to machine the entire boom in order to maintain positioning accuracy.

  The present invention has been made in view of such a point, and an object thereof is to simplify the repairing work of the parts that are in contact with each other when the boom is connected.

  In order to achieve the above object, in the present invention, the scooping pin or hook can be easily replaced.

Specifically, in the first invention, a first boom having a scooping pin protruding in a horizontal direction on a side plate on one end side;
A second boom non-rotatably coupled to the first boom by a boom connecting pin;
A hook provided on the second boom corresponding to the scooping pin;
When the first boom and the second boom are connected, the second boom and the first boom are relatively centered on the scooping pin with the scooping pin and the hook in contact with each other. It is assumed that the boom of the working machine is rotated to position the boom connecting pin.

  A removable replacement plate is provided on the contact surface of the hook with the scooping pin.

  According to the above configuration, even if it becomes difficult to align the boom connecting pin due to wear of the contact surface of the hook with the scooping pin due to repeated connection between the first boom and the second boom, it is for replacement. If the plate is removed and replaced with a new one, the boom connecting pins can be aligned in the same manner as before wear without machining to maintain alignment accuracy throughout the boom. For this reason, repair work becomes easy.

In the second invention, in the first invention,
A positioning portion is provided for positioning the replacement plate at a predetermined position.

  According to the above configuration, after the replacement plate is removed due to wear, when the new replacement plate is mounted again, the replacement plate is positioned by the positioning portion that is not affected by the wear, so positioning accuracy is easily maintained. be able to. For this reason, the replacement work is extremely easy without machining to maintain the alignment accuracy of the entire boom.

In the third invention, in the second invention,
A positioning guide member as the positioning portion protrudes from the horizontal outer surface of the hook,
The replacement plate is fixed to the hook in a state of being positioned in contact with the positioning guide member.

  According to the above configuration, after the replacement plate is removed, the positioning accuracy can be easily maintained by fixing the new replacement plate along the non-wearing positioning guide member provided on the outer surface in the horizontal direction of the hook. be able to. For this reason, the replacement work is extremely easy without machining to maintain the alignment accuracy of the entire boom.

In the fourth invention, in the third invention,
The replacement plate is fixed to the hook by welding.

  According to the above configuration, when the replacement plate is removed due to wear, even if the welded portion is shaved with a grinder or cut with gas, the replacement plate is removed and brought into contact with the positioning guide member again. If a new replacement plate is welded in this state, the positioning accuracy can be easily maintained. For this reason, the replacement work is extremely easy without machining to maintain the alignment accuracy of the entire boom.

In the fifth invention, in the third invention,
The replacement plate is fixed to the hook by bolt fastening.

  According to the above configuration, when the replacement plate is removed due to wear, it is only necessary to loosen the fastening member. After the replacement plate is removed, the replacement plate is fastened again with the positioning guide member in contact with the replacement plate. Since the members only need to be fastened, the positioning accuracy can be easily maintained. For this reason, the replacement work is extremely easy without machining to maintain the alignment accuracy of the entire boom.

In a sixth invention, in the first invention,
The replacement plate is
A fitting portion as the positioning portion that fits on the inner peripheral surface side of the hook; and
A fixing portion that contacts the side surface of the hook,
The replacement plate is positioned with respect to the hook by the fitting portion, and the fixing portion is fixed to the hook in the positioned state.

  According to the above configuration, when the replacement plate is worn out and replaced with a new replacement plate, positioning with respect to the hook is performed at the fitting portion of the replacement plate so that the alignment accuracy is not affected by the wear. Kept. For this reason, the replacement work is extremely easy without machining to maintain the alignment accuracy of the entire boom.

In a seventh invention, in the sixth invention,
The fixing portion covers substantially the entire side surface of the hook,
The fitting portion covers substantially the entire inner peripheral surface of the hook.

  According to the above configuration, the fixing portion of the replacement plate covers substantially the entire side surface from the tip of the hook, so that the step between the hook and the replacement plate is eliminated and the appearance is improved, and the fitting portion is Since it covers almost the entire inner peripheral surface, it is hooked with the scooping pin in contact with the inside near the hook tip. From this state, the scooping pin slides on the inner peripheral surface of the hook to the final position. Even in such a case, the inner peripheral surface of the hook can be effectively protected.

In the eighth invention, in the sixth or seventh invention,
The replacement plate is fixed to the hook by welding.

  According to the above configuration, when removing the replacement plate due to wear, even if the welded portion is shaved with a grinder or cut with gas, the fitting portion is protected with dimensional accuracy again after the replacement plate is removed. If the new replacement plate is welded after positioning by the above, positioning accuracy can be easily maintained. For this reason, the replacement work is extremely easy without machining to maintain the alignment accuracy of the entire boom.

In the ninth invention, in the sixth or seventh invention,
The replacement plate is fixed to the hook by bolt fastening.

  According to the above configuration, when the replacement plate is removed due to wear, it is only necessary to loosen the fastening member, and after the replacement plate is removed, the fastening member is positioned again by positioning at the fitting portion with dimensional accuracy. Since it only has to be fastened, it is easy to maintain positioning accuracy. For this reason, the replacement work is extremely easy without machining to maintain the alignment accuracy of the entire boom.

In a tenth invention, based on the above assumptions,
The scooping pins are welded to the outer surface side of the periphery of each through hole in a state of being inserted through the through holes formed in the pair of side plates of the first boom,
On the periphery of the through hole, there are formed a melted portion that has been melted by the welding and a guide portion that is not melted and has a machined surface.

  That is, by repeating the connection between the first boom and the second boom, the contact surface of the boom connecting pin with the scooping pin of the hook wears down, making it difficult to align the boom connecting pin. It needs to be replaced. When exchanging, the guide part will not be damaged even if the welded part of the scooping pin and the side plate of the first boom is melted away with a grinder or gas, so that the guide part will not be damaged. By inserting the pin through the guide section with dimensional accuracy, the scooping pin is positioned, and if the scooping pin and the side plate are welded again in that state, there is no need to machine the entire boom. The repair work is extremely easy.

In an eleventh aspect, in the tenth aspect,
The periphery of the through hole is composed of a single side plate,
The penetration part is formed on the outer surface side of the one side plate,
The guide portion is formed on the inner surface side of the one side plate.

  According to the above configuration, by making the thickness of the side plate larger than the amount of penetration due to welding, only the outer surface side of the side plate is melted by welding heat to become a penetration portion, and the remaining portion is dimensioned without being affected by heat. It becomes a guide part with maintained accuracy. Therefore, when replacing the scooping pin, even if the welded part of the scooping pin and the side plate of the first boom melts away with a grinder or gas, the guide part is not damaged, so the worn scooping pin After removal, the new scooping pin is inserted into the guide section with dimensional accuracy so that positioning of the scooping pin is performed, and if the scooping pin and side plate are welded again in this state, the entire boom Repair work is extremely easy without the need for machining.

In a twelfth aspect, in the tenth aspect,
The periphery of the through hole is composed of one side plate and a reinforcing plate attached to the inner surface of the side plate,
The penetration portion is formed on at least a part of the side plate,
At least a part of the guide portion is formed on the reinforcing plate.

  According to the above configuration, the thickness of the side plate is not sufficient, and even if the welding causes heat to melt into the majority of the side plate due to welding heat, the reinforcing plate is not easily affected by heat and can easily maintain dimensional accuracy. Part. For this reason, when replacing the scooping pin, even if the welded part of the scooping pin and the side plate of the first boom is cut off by the grinder or gas and the melted part of the side plate is cut off, the reinforcing plate guide part is free from damage. After removing the worn scooping pin, the new scooping pin is inserted into the guide with high dimensional accuracy to position the scooping pin, and in that state, the scooping pin and the side plate are welded again. For example, there is no need for machining the entire boom, and repair work is extremely easy.

In a thirteenth invention, in the tenth invention,
An annular member having an insertion hole through which the scooping pin is inserted is joined to the inner surface side of the peripheral edge of the through hole, and a recessed portion that is one step lower is formed on the inner peripheral surface of the annular member on the side plate side,
The said guide part is formed in annular member inner periphery other than the said recessed part.

  According to the above configuration, the thickness of the side plate is not sufficient, and even if the weld is melted largely by welding heat to form a melted portion, a gap due to the recess is formed between the annular member and the side plate. Therefore, when replacing the scooping pin, even if the welded part of the scooping pin and the side plate of the first boom is cut off with the gas at the melted part of the side plate, almost no heat is transferred to the inner periphery of the annular member other than the recess. It is maintained as a guide part with dimensional accuracy maintained. For this reason, after the worn scooping pin is removed, the new scooping pin is inserted into the guide part with dimensional accuracy, so that the scooping pin is positioned again. If welding is performed, even a thin side plate does not require machining for the entire boom, and repair work is extremely easy.

In the fourteenth invention, based on the above assumptions,
The scooping pin has a flange portion, and the flange portion and a through-hole periphery formed in the side plate of the first boom are configured to be fastened.

  That is, by repeating the connection between the first boom and the second boom, the contact surface of the hook with the scooping pin is worn and it becomes difficult to align the boom connecting pin, and it is necessary to replace the scooping pin. Arise. Even in such a case, in the above configuration, the scooping pin and the side surface of the first boom are not directly welded. Therefore, the scooping pin that is easily worn by releasing the fastening between the collar portion and the first boom. Is removed. After the removal, since the dimensional accuracy can be easily maintained by re-fastening the collar portion of the new scooping pin and the first boom, the machining work is not necessary for the entire boom, and the repair work is extremely easy.

  As described above, according to the present invention, it is possible to replace the scooping pins or hooks that come into contact with each other when the boom is connected, thereby simplifying the repair work of the part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 shows a hydraulic excavator 1 as a working machine provided with a boom 10 of the working machine according to the embodiment of the present invention. The hydraulic excavator 1 includes a lower traveling body 3 having a crawler 2 and the lower traveling body 3. And an upper revolving body 4 supported so as to be freely rotatable.

  A boom foot 5 of the upper swing body 4 supports a lower end of a main boom 6 as a first boom and a lower end of a main boom cylinder 7 that raises and lowers the main boom 6 around a boom foot pin 5a. When the boom is rearranged, the boom 10 above the main boom 6 is supported by the boom support 30.

  Various booms can be connected to the tip of the main boom 6. In the present embodiment, as shown also in FIG. 8, the intermediate boom 8 as the second boom is coupled by a pair of boom connecting pins 9 so as not to rotate.

  Further, as shown in an enlarged view in FIG. 3, a boss portion 6 b for inserting a cylinder pin 7 a that supports the upper end of the main boom cylinder 7 bulges horizontally on the side plate 6 a of the main boom 6. In addition, a pair of back side pin insertion holes 6 c and abdominal surface side pin insertion holes 6 d for inserting the boom connecting pins 9 are formed at the upper end of the main boom 6. In the vicinity of the back side pin insertion hole 6c, a scooping pin 18 is provided so as to protrude in the horizontal direction.

  As shown in an enlarged view in FIG. 4, the scooping pins 18 are welded to the outer surface side of the peripheral edge of each side plate through-hole 6 e while being inserted into the side plate through-holes 6 e formed in the pair of side plates 6 a of the main boom 6. Has been. Thus, a welded portion 18a as a penetration portion is formed on the outer surface side of the side plate 6a. An annular member 19 having an insertion hole 19a through which the scooping pin 18 is inserted is joined to the inner surface side (right and left inner sides) of the peripheral edge of each side plate through-hole 6e. On the inner peripheral surface of the annular member 19 on the side plate 6a side (right and left outer sides), a recessed portion 19b that is one step lower is formed. For this reason, a gap 19 c is formed between the inner surface side of the peripheral edge of each side plate through-hole 6 e and the side plate 6 a side of the annular member 19. What is necessary is just to set the magnitude | size of the clearance gap 19c according to the magnitude | size of the welding part 18a. With this configuration, a guide portion having a machined surface is formed in the insertion hole 19a.

  And as shown in FIG. 2, the lower end of the arm cylinder 12 is connected with the back side of the intermediate | middle boom 8 so that rotation is possible. A base end side of the arm 13 is rotatably supported on the upper end of the intermediate boom 8, and an upper end of the arm cylinder 12 is rotatably connected to the base end side of the arm 13. Thus, the intermediate boom 8 and the arm 13 are connected so as to be relatively rotatable.

  A proximal end side of a bucket (not shown) is rotatably connected to the distal end of the arm 13, and a bucket link 16 is connected to the proximal end side of the bucket and the distal end side of the arm 13. Further, the tip of the bucket cylinder 15 is connected to the bucket link 16, and the base end side of the bucket cylinder 15 is connected to the base end side of the arm 13. Thus, the bucket is connected to the arm 13 so as to be rotatable relative to the arm 13.

  As shown enlarged in FIG. 1, left and right side plates 20 that sandwich the upper end of the main boom 6 from both left and right sides are provided on the lower end side of the intermediate boom 8, and the boom connecting pins 9 are inserted into the left and right side plates 20, respectively. A pair of outer insertion holes 20a, 20b is provided. A hook-like hook 21 is formed in the vicinity of the rear side outer insertion hole 20a so as to open downward corresponding to the scooping pin 18. Supporting pins 31 for supporting the intermediate boom 8 on the boom support base 30 project from the upper left side of the left right side plate 20.

  As shown in an enlarged cross-sectional view in FIG. 5, a replacement plate 22 made of a substantially U-shaped steel plate that can be removed is mounted on the contact surface of the hook 21 with the scooping pin 18. The replacement plate 22 has a fitting portion 22 a as a positioning portion that fits on the inner peripheral surface side of the hook 21, and a fixing portion 22 b that abuts on the side surface side of the hook 21. That is, the fitting portion 22a is formed at the portion along the lower peripheral edge of the hook 21 remaining after the inner surface side of the replacement plate 22 is cut, and the fixing portion 22b is formed at the remaining cut portion. The replacement plate 22 is positioned with respect to the hook 21 by the fitting portion 22a.

  Further, a positioning guide member 23 as an arcuate positioning portion protrudes from the horizontal outer surface of the hook 21, and the replacement plate 22 has a rear side peripheral edge that abuts against the positioning guide member 23. It is also positioned by touching. In this state of positioning, the replacement plate 22 is welded to the positioning guide member 23 (the welded portion is indicated by reference numeral 22c). The replacement plate 22 and the hook 21 are not welded except at the positioning guide member 23 portion. The positioning guide member 23 and the hook 21 may be welded to each other, may be formed by cutting out from the base material of the hook 21, or may be fixed to the hook 21 by bolt fastening. The contact surface of the replacement plate 22 with the scooping pin 18 is machined to maintain dimensional accuracy.

-Boom connection method-
Next, the connection method of the boom 10 concerning this embodiment is demonstrated.

  First, as shown in FIG. 2, an intermediate boom 8, an arm cylinder 12, an arm 13, and a bucket cylinder 15 connected in advance are supported on a boom support base 30. At this time, the bucket may be connected to the bucket link 16. A hydraulic excavator 1 to which the main boom 6 and the main boom cylinder 7 are connected is also prepared.

  Next, as shown by a two-dot chain line in FIG. 6, the crawler 2 of the excavator 1 is advanced with the main boom 6 lowered, and then the main boom 6 is raised and scooped up as shown by the solid line in FIG. The pin 18 is hooked on the hook 21.

  Next, as shown in FIG. 7, the main boom 6 is further raised with the scooping pin 18 and the hook 21 in contact with each other, and the intermediate boom 8 and the main boom 6 are relatively moved around the scooping pin 18. The intermediate boom 8 is lifted from the boom support base 30, and the rear side pin insertion hole 6c and the outer insertion hole 20a are aligned. Then, the boom connecting pin 9 is inserted into the aligned pin insertion hole 6c and the outer insertion hole 20a.

  Next, as shown in FIG. 8, the main boom 6 is further raised to position the abdominal surface side pin insertion hole 6d and the outer insertion hole 20b, and the boom connection pin 9 is connected to the abdominal surface side pin insertion hole 6d and the outer insertion hole 20b. Insert. Thereby, the main boom 6 and the intermediate | middle boom 8 are connected so that rotation is impossible.

  On the other hand, when the connection between the main boom 6 and the intermediate boom 8 is disconnected, the operation opposite to the above operation is performed.

  When such reconnection is repeated, the contact surface between the hook 21 and the scooping pin 18 is worn. Then, in the alignment work of the back side pin insertion hole 6c and the outer insertion hole 20a shown in FIG. 6, the dimensional accuracy is incorrect, and the insertion of the boom connecting pin 9 becomes difficult. In such a case, it is necessary to replace the scooping pin 18 or the hook 21.

-Replacement plate replacement method-
First, a method for replacing the replacement plate 22 will be described. As shown in FIG. 5, in order to remove the replacement plate 22, the welded portion 22c with the positioning guide member 23 is shaved with a grinder or cut with gas. Then, the coupling between the replacement plate 22 and the positioning guide member 23 is released, and the replacement plate 22 is removed. At this time, since the positioning guide member 23 is provided, the outer surface of the hook 21 is less likely to be affected by heat as compared with the case where the replacement plate 22 is directly welded to the outer surface of the hook 21.

  After the replacement plate 22 is removed, the new replacement plate 22 is positioned again along the positioning guide member 23. The positioning may be performed by the fitting portion 22a. Then, the peripheral edge of the replacement plate 22 is welded again along the positioning guide member 23.

  Then, the replacement plate 22 is easily machined on the contact surface with the scooping pin 18 to maintain the positioning accuracy, and the replacement plate 22 is positioned by the positioning guide member 23 and the fitting portion 22a. Therefore, the dimensional accuracy of the intermediate boom 8 as a whole can be maintained. For this reason, it is not necessary to perform machining to maintain the alignment accuracy of the entire intermediate boom 8, and the replacement work is extremely easy.

−Replacement method of scooping pin−
Next, a method for replacing the scooping pin 18 will be described. When the outer periphery of the scooping pin 18 is worn out, it is necessary to replace the scooping pin 18.

  First, as shown in FIG. 4, the welded portion 18a between the scooping pin 18 and the side plate 6a of the main boom 6 is cut off with a grinder or gas. At this time, especially when cutting with gas, the side plate 6a is affected by heat, and the shape of the side plate through hole 6e is likely to change. However, since the gap 19c is formed by the recess 19b between the annular member 19 and the side plate 6a, it is possible to avoid the insertion hole 19a of the annular member 19 from being affected by heat or being damaged.

  Next, after the scooping pin 18 is removed, the new scooping pin 18 is inserted into the insertion hole 19a of the annular member 19 whose dimensional accuracy is maintained. Thus, the scooping pin 18 is positioned.

  Next, welding is again performed between the scooping pin 18 and the side plate 6a. Then, since the insertion hole 19a of the annular member 19 maintains the dimensional accuracy, there is no need for machining or the like in the entire intermediate boom 8, and repair work is extremely easy.

  Therefore, according to the boom 10 of the working machine according to the present embodiment, the scooping pins 18 or the hooks 21 that come into contact with each other when the intermediate boom 8 and the main boom 6 are connected can be replaced, so that the work for repairing the worn part is performed. Can be greatly simplified.

  In the above embodiment, the fitting portion 22a is provided by providing a step on the inner surface side of the replacement plate 22, but the fitting portion 22a is not necessarily required. Even if the fitting portion 22a is not provided, the positioning guide member 23 can ensure the positioning accuracy of the replacement plate 22. Conversely, even if the positioning guide member 23 is not provided, the positioning accuracy of the replacement plate 22 can be ensured by the fitting portion 22a.

-Modification 1 of embodiment-
9 and 10 show a first modification of the embodiment of the present invention, which differs from the above embodiment in that the mounting structure of the replacement plate 122 is different. In the following modification, the same parts as those in FIGS. 1 to 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

  Also in this modified example, a positioning guide member 123 as a positioning portion having the same shape as that of the above-described embodiment protrudes from the surface of the hook 21 in the horizontal direction, similarly to the positioning guide member 23 of the above-described embodiment. ing. The positioning guide member 123 and the hook 21 may be welded, the positioning guide member 123 may be formed by cutting out from the base material of the hook 21, and the positioning guide member 123 is also attached to the hook 21. On the other hand, you may fix by bolt fastening.

  For example, a pair of bolt insertion holes 122a are opened in each replacement plate 122 of this modification. The hook 21 is also provided with a pair of bolt holes 21a corresponding to the bolt insertion holes 122a.

  Each replacement plate 122 is fastened to the hook 21 with two fastening bolts 124 as fastening members in a state where the peripheral edge is in contact with the positioning guide member 123. The contact surface of the replacement plate 122 with the scooping pin 18 is machined in the same manner as in the above embodiment to maintain dimensional accuracy.

  With such a configuration, when the replacement plate 122 is removed, it is only necessary to loosen the fastening bolt 124. After the replacement plate 122 is removed, the replacement plate 122 is brought into contact with the positioning guide member 123. Therefore, the fastening bolt 124 can be fastened again, so that the positioning accuracy can be easily maintained. For this reason, the replacement work is extremely easy without machining to maintain the alignment accuracy of the entire intermediate boom 8.

  In the present modification, the replacement plate 122 is not provided with the fitting portion 22a as in the above embodiment, but may similarly be provided with a fitting portion and a fixing portion. In that case, the positioning guide member 123 is not necessarily provided, and the replacement plate 122 may be positioned at the fitting portion.

-Modification 2 of embodiment-
11 and 12 show a second modification of the embodiment of the present invention, which differs from the above embodiment mainly in that the shape of the replacement plate 222 is different.

  That is, in the present modification, the fixing portion 222b covers substantially the entire side surface of the hook 21 and has a shape along the outer shape line of the hook 21, so that the appearance is improved. The hook 21 referred to here is a hook-like portion protruding to the base end side (the main boom 6 side) of the left and right side plates 20, and the substantially entire side surface means strictly all the side surfaces of the hook 21. Rather, it means that part of it need not be covered.

  Further, the fitting portion 222a covers substantially the entire inner peripheral surface of the hook 21 on which the scooping pin 18 may come into contact. The meaning of substantially the whole at this time means substantially the whole when the portion of the hook 21 with which the scooping pin 18 can come into contact is seen from the side, and only the right and left outer portions of the inner peripheral surface of the hook 21 are fitted. The portion 222a may be covered.

  As shown in FIG. 11, the hook 21 is provided with a pair of bolt holes 21a, and a pair of bolt insertion holes (not shown) are opened in the replacement plate 222 so as to correspond to the bolts 21a. Bolts 124 are inserted into the bolt insertion holes and fastened to the bolt holes 21a. Further, as shown in FIG. 12, four bolts 124 may be fastened. In either case, the replacement plate 222 can be removed simply by loosening the bolt 124. When a new replacement plate 222 is attached again, the fitting portion 222a is brought into contact with the inner peripheral surface of the hook 21 and positioned. Thus, high dimensional accuracy can be easily ensured.

  Further, since the fixing portion 222b of the replacement plate 222 covers substantially the entire side surface from the tip of the hook 21, the step between the hook 21 and the replacement plate 222 is eliminated and the appearance is improved.

  Further, since the fitting portion 222a covers substantially the entire inner peripheral surface of the hook 21, it is hooked with the scooping pin 18 in contact with the inside of the vicinity of the tip of the hook 21, and the inner peripheral surface side of the hook 21 is scooped up from this state. Even when the pin 18 slides to reach the final position, the inner peripheral surface of the hook 21 can be effectively protected.

—Modification 3 of Embodiment—
13 and 14 show a second modification of the embodiment of the present invention, which differs from the above embodiment in that the mounting structure of the scooping pin 118 is different.

  The scooping pin 118 has a flange portion 119 welded to one end side (a welded portion is indicated by reference numeral 118a). Four through holes 119a are formed in the flange portion 119, and four screw holes 6f are formed on the periphery of the side plate through hole 6e of the side plate 6a of the main boom 6 so as to correspond to the through hole 119a. By this, the collar part 119 (the scooping pin 118) and the side plate through-hole 6e periphery are comprised so that fastening is possible.

  A washer 120 is fastened to the other end of the scooping pin 118. The washer 120 is also formed with four through holes 120a in the same manner as the flange portion 119, and four screw holes 6f are formed on the periphery of the side plate through hole 6e so as to correspond to the through holes 120a. Thereby, the washer 120 and the side plate through-hole 6e periphery are comprised so that fastening is possible. The washer 120 is not always necessary, but plays the role of positioning the scooping pin 118.

  Also in this modified example, when the scooping pin 118 is replaced, the scooping pin 118 and the side surface of the main boom 6 are not directly welded, so by releasing the fastening between the flange portion 119 and the main boom 6, The easily worn scooping pin 118 is removed. After the removal, if the collar portion 119 (washer 120) of the new scooping pin 118 and the main boom 6 are fastened again, the scooping pin 118 is formed between the screw hole 6f and the inner peripheral surface of the collar portion 119 (washer 120). Therefore, the repair work is extremely easy without the need for machining the entire intermediate boom 8.

(Other embodiments)
The present invention may be configured as follows with respect to the above embodiment.

  That is, in the above embodiment, the annular member 19 is provided and the machining surface is secured by using the insertion hole 19a as a guide portion. However, the annular member 19 is not necessarily provided, and the thickness of the side plate 6a is increased. By making it sufficiently large, a guide portion can be formed on the inner surface side of the side plate 6a so as to ensure a machined surface without being affected by the heat when the scooping pin 18 is welded or removed. Furthermore, when the thickness of the side plate 6a cannot be secured, a reinforcing plate may be attached to the inner surface side of the side plate 6a and the guide portion may be secured by this reinforcing plate.

  In the above embodiment, the scooping pins 18 and 118 and the replacement plates 22 and 122 are configured to be replaceable. However, at least one of the scooping pins 18 and 118 and the replacement plates 22 and 122 can be replaced. You may comprise.

  In the above-described embodiment, the configuration in which the hook 21 is placed on the scooping pin 18 is shown, but conversely, as shown in Patent Document 1, the scooping pin may be placed on the hook. In that case, an upward opening hook is provided at the upper end of the main boom serving as the second boom, and the upward inner peripheral surface of the hook is in contact with the scooping pin provided at the lower end of the upper boom serving as the first boom. What is necessary is just to comprise.

  Moreover, in the said embodiment, although the 2nd boom is comprised as the intermediate | middle boom 8 which connects the arm 13 rotatably, the structure of a 2nd boom is not limited to this, The intermediate | middle boom is supported rotatably. The main front boom may be configured.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or a use.

It is a side view which expands and shows the intermediate | middle boom in the boom of the working machine concerning embodiment of this invention. It is a side view which shows one process of connecting a boom. It is a side view which expands and shows a main boom. It is the IV-IV sectional view taken on the line of FIG. It is the VV sectional view taken on the line of FIG. It is a side view which shows one process of connecting a boom. It is a side view which shows one process of connecting a boom. It is a side view which shows one process of connecting a boom. FIG. 9 is a view corresponding to FIG. 1 according to a first modification of the embodiment of the present invention. FIG. 10 is a sectional view taken along line XX in FIG. 9. It is an expanded side view of the hook in the case of two bolts concerning the modification 2 of embodiment of this invention, and its periphery. It is an enlarged side view of the hook in the case of four bolts concerning the modification 2 of embodiment of this invention, and its periphery. FIG. 6 is a view corresponding to FIG. 3 according to a second modification of the embodiment of the present invention. It is the XIV-XIV sectional view taken on the line of FIG.

1 Excavator (work machine)
6 Main boom (first boom)
6a Side plate 6c, 6d Pin insertion hole (through hole)
8 Intermediate boom (second boom)
9 Boom connecting pin 18 Scooping pin 18a Welded part (penetrating part)
19 annular member 19a insertion hole (guide part)
19b Recessed part 21 Hook 22 Replacement plate 22a Fitting part (positioning part)
22b Fixed part 23 Positioning guide (Positioning part)
118 Scooping pin 119 collar 122 replacement plate 123 positioning guide (positioning part)
124 Fastening bolt (fastening member)
1

Claims (14)

A first boom having a scooping pin projecting horizontally on a side plate on one end side;
A second boom non-rotatably coupled to the first boom by a boom connecting pin;
A hook provided on the second boom corresponding to the scooping pin;
When the first boom and the second boom are connected, the second boom and the first boom are relatively centered on the scooping pin with the scooping pin and the hook in contact with each other. A boom of a work machine in which the boom connecting pin is aligned by rotating to
A boom for a working machine, wherein a removable replacement plate is provided on a contact surface of the hook with the scooping pin. In the boom of the working machine according to claim 1,
A boom for a working machine having a positioning portion for positioning the replacement plate at a predetermined position. In the boom of the working machine according to claim 2,
A positioning guide member as the positioning portion protrudes from the horizontal outer surface of the hook,
The boom of a working machine, wherein the replacement plate is fixed to the hook in a state of being positioned in contact with the positioning guide member. In the boom of the working machine according to claim 3,
The boom of a working machine, wherein the replacement plate is fixed to the hook by welding. In the boom of the working machine according to claim 3,
The boom of a working machine, wherein the replacement plate is fixed to the hook by bolt fastening. In the boom of the working machine according to claim 1,
The replacement plate is
A fitting portion as the positioning portion that fits on the inner peripheral surface side of the hook; and
A fixing portion that contacts the side surface of the hook,
The boom for a working machine, wherein the replacement plate is positioned with respect to the hook by the fitting portion, and the fixing portion is fixed to the hook in the positioned state. In the boom of the working machine according to claim 6,
The fixing portion covers substantially the entire side surface of the hook,
The boom of a working machine, wherein the fitting portion covers substantially the entire inner peripheral surface of the hook. In the boom of the working machine according to claim 6 or 7,
The boom of a working machine, wherein the fixing portion is fixed to the hook by welding. In the boom of the working machine according to claim 6 or 7,
The boom of a working machine, wherein the fixing portion is fixed to the hook by bolt fastening. A first boom having a scooping pin projecting horizontally on a side plate on one end side;
A second boom non-rotatably coupled to the first boom by a boom connecting pin;
A hook provided on the second boom corresponding to the scooping pin;
When the first boom and the second boom are connected, the second boom and the first boom are relatively centered on the scooping pin with the scooping pin and the hook in contact with each other. A boom of a work machine in which the boom connecting pin is aligned by rotating to
The scooping pins are welded to the outer surface side of the periphery of each through hole in a state of being inserted through the through holes formed in the pair of side plates of the first boom,
A boom for a working machine, characterized in that a penetration portion that has been melted by the welding and a guide portion that is not melted and has a machined surface are formed on the periphery of the through hole. In the boom of the working machine according to claim 10,
The periphery of the through hole is composed of a single side plate,
The penetration part is formed on the outer surface side of the one side plate,
The boom of a working machine, wherein the guide portion is formed on an inner surface side of the one side plate. In the boom of the working machine according to claim 10,
The periphery of the through hole is composed of one side plate and a reinforcing plate attached to the inner surface of the side plate,
The penetration portion is formed on at least a part of the side plate,
A boom for a working machine, wherein at least a part of the guide portion is formed on the reinforcing plate. In the boom of the working machine according to claim 10,
An annular member having an insertion hole through which the scooping pin is inserted is joined to the inner surface side of the peripheral edge of the through hole, and a recessed portion that is one step lower is formed on the inner peripheral surface of the annular member on the side plate side,
The boom of a working machine, wherein the guide portion is formed on an inner periphery of an annular member other than the recess. A first boom having a scooping pin projecting horizontally on a side plate on one end side;
A second boom non-rotatably coupled to the first boom by a boom connecting pin;
A hook provided on the second boom corresponding to the scooping pin;
When the first boom and the second boom are connected, the second boom and the first boom are relatively centered on the scooping pin with the scooping pin and the hook in contact with each other. A boom of a work machine in which the boom connecting pin is aligned by rotating to
The scooping pin has a collar part, and the boom of the working machine is configured such that the collar part and a through-hole periphery formed in a side plate of the first boom can be fastened.

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