JP2004092143A - Bracket structure for work unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bracket structure which prevents cracking at a welding portion with respect to a base metal even if the distance between the welding portion and the end of each bracket plate is short. <P>SOLUTION: The bracket structure for a work unit is formed by fixing a pair of the bracket plates 55a to the base metal 40aa by a welding means, and inserting a pin 46 into the bracket plates 55a, whereby the load of a cylinder 57 is borne via the pin 46 and the bracket plates 55a by the base metal 40aa. According to the bracket structure, a width-increasing section 55c for increasing the width dimension of an abutting portion of a bracket 55 on the base metal 40aa, is formed at an end opposite to a direction that extends the cylinder 57, and then a welding bead between the end of the bracket 55 and the base metal 40aa is arranged over the entire length of the width-increasing portion 55c. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bracket structure for connecting a hydraulic cylinder, a link, and the like provided in a working machine having a working mechanism such as a hydraulic shovel.
[0002]
[Prior art]
FIG. 12 shows a side view of the excavator. In this drawing, reference numeral 1 denotes a traveling body, and 2 denotes a revolving body which is attached to the traveling body 1 so as to be able to pivot. 4 is a boom, 5 is an arm, 6 is a bucket, 7 is a boom cylinder for raising and lowering the boom, 8 is an arm cylinder for rotating the arm, 9 is a bucket cylinder for rotating the bucket, and 10 is a bucket cylinder. Links are shown, and these constitute the working mechanism 3. 11 is a bracket to which the bottom side of the arm cylinder is connected, 12 is a bracket to which the bottom side of the bucket cylinder is connected, 13 is a bracket to which the rod side of the arm cylinder 8 is connected, 14 is a connection between the tip of the boom 4 and the arm 5 It is a pin.
[0003]
FIG. 13 shows another example of a working mechanism attached to a hydraulic excavator. Unlike the working mechanism 3, the boom is divided into two parts, and the same parts as those in FIG. 12 are denoted by the same reference numerals and description thereof is omitted.
[0004]
In FIG. 13, reference numeral 40 denotes a two-piece boom, in which a first boom 40a and a second boom 40b are connected by pins 43, and a rear end pin 44 of the second boom 40b and a bracket 45 provided on the first boom 40a. A pin 46 is connected to the pin 46 by a positioning cylinder 47. Reference numeral 41 denotes a foot connecting pin of the first boom 40a, and reference numeral 42 denotes a connecting pin on the revolving unit side of the boom cylinder 7, which is connected to a bracket provided on the revolving unit 2 (not shown).
[0005]
By using this two-piece type boom, for example, in the case of work requiring excavation reach, the positioning cylinder 47 is contracted so that the position of the tip pin 14 of the second boom 40b moves away from the foot pin 41 of the first boom 40a. Is positioned. Further, for example, in the case of an operation where a digging depth is required, it is possible to dig deeper by extending the positioning cylinder 47 and bringing the tip pin 14 closer to the boom foot pin 41 side.
[0006]
Next, a bracket of a hydraulic cylinder provided in the above working mechanism will be described with reference to FIGS. 14 and 15, for example, as shown in Japanese Patent Application Laid-Open No. 9-3955. FIG. 14 is a perspective view of the bracket 12 of the bucket cylinder 9 shown in FIG. 12 and FIG. FIGS. 15A and 15B are views for explaining a strong surface of the bracket as described above, wherein FIG. 15A is a plan view of the bracket, and FIG. 15B is a front view thereof.
[0007]
In FIG. 14, 5a is an upper plate of the arm 5, 5b, 5b is a side plate, and 5c is a lower plate. These connecting portions are fixed by welding, and the arm 5 has a box-shaped cross section. Reference numeral 12a denotes a bracket plate of the bracket 12, whose lower side is vertically joined to the upper plate 5a of the arm 5, and this joint is welded. A boss 12b is welded to the bracket plate 12a, and has a connecting pin hole provided with the bracket plate 12a. The bracket plate 12a and the boss 12b are made symmetrical left and right, and the bearing of the bucket cylinder 9 is inserted between the left and right brackets and connected by the connecting pin 12c.
[0008]
Next, the operation of the bracket 12 will be described with reference to FIGS. The bracket 12 receives the load generated in the cylinder 9 via the connecting pin 12c. Since the lower sides of the left and right bracket plates 12a are welded to the upper plate 5a, the welds bear the load and transmit the load to the upper plate 5a.
[0009]
At this time, if the extension distance from the connecting pin 12c of the bracket to the end of the bracket plate 12a in the direction opposite to the direction in which the cylinder 9 extends is a short dimension L1, a large load acts on the end and the load is increased. Is transmitted to and received by the upper plate 5a with a narrow welding length corresponding to the plate thickness of the bracket plate 12a. Therefore, when stress concentration occurs and a repeated load is applied, the end of the bracket and the upper plate 5a Cracks may occur at the weld bead toe of the butted weld L1b. Factors such as the thickness of the upper plate, the thickness of the bracket, and the welding method may be considered as the causal relationship between the extension distance to the end of the bracket and the occurrence of cracks. Depending on the combination of these, namely the thickness of the bracket plate and the upper plate, the thickness of the upper plate, the shape of the welding, etc., cracks may occur in the upper plate due to stress concentration as described above, or cracks may occur in the weld bead. Sometimes.
[0010]
As a countermeasure, for example, it is possible to prevent the occurrence of cracks by increasing the thickness of the upper plate while keeping the extension distance at the short dimension L1, but since the plate thickness increases over the entire upper plate having a large area, There is a problem that the weight of the mechanism is greatly increased. Also, even if the thickness of the bracket plate is increased and the welding length with the base material (upper plate) is increased to prevent stress concentration, the effect of preventing crack generation is expected unless the thickness of the bracket plate is increased. Can not.
[0011]
Here, the extension distance of the bracket plate is extended to L2 which is longer than L1 and is inclined toward the end of the bracket plate so that the load received from the cylinder is gradually reduced, so that the load is applied at the end L2b of the bracket plate. The load to be applied can be reduced, and the occurrence of cracks in the welded portion can be prevented.
[0012]
[Problems to be solved by the invention]
However, there is also a demand for working equipment to attach and work with a large-capacity bucket capable of excavating more, or to attach a robust bucket capable of excavating harder ground. When manufacturing a working mechanism that meets such working conditions, for example, the working range may be sacrificed, but the length of the arm 5 may be shortened. Even in such a working machine, a predetermined angle is required for the rotation angle of the bucket, so that the stroke of the bucket cylinder needs to be equal to that of the standard machine. Therefore, it is necessary to move the position of the bracket 12 for mounting the bucket cylinder 9 backward by the length of the arm 5 shortened. Then, there arises a problem that L2 having a long dimension of the extension distance of the bracket plate necessary for preventing the occurrence of cracks cannot be secured.
[0013]
Further, the two-piece type boom working machine shown in FIG. 13 has the following problem. As described above, in the two-piece boom type working mechanism, the working range can be changed by changing the angle between the first boom 4a and the second boom 4b connected by the connecting pin 43 by extending and retracting the positioning cylinder 47. Has one feature. Here, the positioning cylinder 47 has the above-mentioned function and bears a force such as an excavation reaction force applied to the second boom 4b with the connecting pin 43 as a fulcrum. From the viewpoint of cost, the cylinder is preferably as small as possible. However, in order to secure a necessary reaction force moment, it is necessary to increase the distance L3 between the connecting pins 43 and 44 as much as possible. On the other hand, when the distance L3 is increased, the rotation angle of the first boom 4a and the second boom 4b by the positioning cylinder 47 is reduced. Therefore, in order to obtain the same rotation angle, the stroke of the positioning cylinder 47 needs to be as large as possible. is there. Therefore, the bracket 45 for the connecting pin 46 to which the positioning cylinder 47 is attached must be closer to the boom foot pin 41 by the length of the stroke of the positioning cylinder 47, and the extension distance L2 of the bracket plate necessary for preventing cracking is secured. A problem arises that it cannot be performed.
[0014]
Accordingly, the present invention has been made in view of the above problems, and provides a bracket structure that can prevent cracks from occurring even if it is not possible to secure the necessary extension distance of the end of the bracket plate in the direction opposite to the direction in which the cylinder extends. With the goal.
[0015]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a working machine in which a pin is inserted between a pair of brackets fixed to a base material by welding means, and a load of a cylinder is received by the base material via the pins and the bracket. In the bracket structure, an amplifying portion for increasing the widthwise dimension of the abutting portion against the base material is provided at an end of the bracket in a direction opposite to a direction in which the cylinder extends in each bracket. A weld bead between the bracket end and the base material is provided so as to extend over the entire length of the amplification section. As a result, the load borne by the bracket plate is also distributed to the amplifying portion and can be transmitted to and received by the base material, so that stress concentration can be avoided and cracks in the weld bead portion can be prevented.
[0016]
Further, the amplifying portion is formed of a reinforcing plate provided so as to bridge between the two brackets, and the reinforcing plate is fixed to the both brackets by welding means and welds the abutting portion to the base material. It is configured to be fixed by means. By doing so, the load from the cylinder can be dispersed well, and the weld bead toe of the abutment portion with the base material of both the bracket plate and the reinforcing plate is formed substantially linearly in a direction orthogonal to the bracket plate. Therefore, the occurrence of local stress concentration can be reduced and the occurrence of cracks can be prevented.
[0017]
Further, the reinforcing plate extends toward the cylinder mounting side to a position where the reinforcing plate does not interfere with the operation of the cylinder, and the end of the reinforcing plate has a concave curve shape. Can be transmitted to the reinforcing plate with little change in shape and smoothly so that the occurrence of stress concentration is minimized, so that the concentration of stress on the cylinder mounting side of the reinforcing plate can be avoided and the occurrence of cracks can be prevented.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing an example in which the present invention is applied to a bracket 45 for a positioning cylinder 47 provided on the first boom 40a. 2 is a plan view of the bracket of FIG. 1, and FIG. 3 is a front view of the same. 4 is a central sectional view of the bracket portion shown by an arrow Y in FIG. 2, FIG. 5 is a plan view of FIG. 4, FIG. 6 is an enlarged view of an end of the bracket shown by an X mark in FIG. 4, and FIG. It is sectional drawing shown by the arrow. In the drawings of the present invention, the same components as those shown in the prior art are denoted by the same reference numerals, and description thereof will be omitted.
[0019]
First, in FIG. 1, 40aa is an upper plate (base material) of the first boom 40a, 40ab is a side plate, and 40ac is a lower plate. These connecting portions are fixed by welding, and the cross section of the first boom 40a has a box structure. It has become. 48a is a boss at the foot of the first boom 40a, 48b is a connecting member for connecting the bosses 48a to the thin substrate, and is a thin member for the left and right bosses 48a as bearings to suppress an increase in weight. Made of thick. The connecting portions of these elements are fixed by welding to form the foot portion of the first boom 40a, and the foot pins 41 are inserted into the foot pin holes 41a and connected to the revolving unit 2 (not shown). 55 is a bracket of the present invention, and 57 is a positioning cylinder.
[0020]
Next, in FIGS. 2 and 3, reference numeral 55a denotes a bracket plate of the bracket 55, and reference numeral 55c denotes a reinforcing plate (amplifying member) provided between the left and right bracket plates 55a. L0 is the extension distance from the connection pin hole of the bracket 55 to the right end of the bracket plate 55a in the direction opposite to the direction in which the positioning cylinder 57 extends. The extension distance L0 requires the bracket 55 to approach the boom foot pin 41 due to the longer stroke of the positioning cylinder 57, and can only secure a distance corresponding to the above-described extension distance L1. That is, assuming that the load received from the positioning cylinder 57 is borne only by the welds at the ends of the left and right bracket plates 55a, this is the distance at which a crack occurs at the weld with the upper plate 40aa. The bracket 55 of the present invention is provided with a reinforcing plate 55c between the left and right bracket plates 55a. The details will be described below with reference to FIGS. 4 to 7 in which main parts of these drawings are enlarged.
[0021]
In FIGS. 4 to 7, reference numeral 55b denotes a boss welded to the left and right bracket plates 55a, and a connecting pin hole 46a is provided together with the bracket plates 55a. The end of the bracket plate 55a in the direction opposite to the direction in which the positioning cylinder 57 extends (abutting portion of the bracket plate) is welded to the upper plate 40aa, and a weld bead thereof is indicated by 55ab. The reinforcing plate 55c connected between the bracket plates 55a has a central portion formed in a concave curve shape as shown by R in the drawing, and both ends thereof are gently inclined toward the connecting pin hole 46a for mounting the cylinder. Its end is extended by a weld bead 55cb as shown in the figure and smoothly welded. Also, the upper surface of the reinforcing plate 55c is welded at the end in contact with the upper plate 40aa with the bracket plate 55a aligned with the inclined surface from the boss portion of the connecting pin 46 toward the end, and the welding bead is 55ca. Show. The toe of the weld bead 55ab of the bracket plate 55a and the upper plate 40aa and the toe of the weld bead 55ca of the reinforcing plate 55c and the upper plate 40aa form a toe 60 substantially aligned with the toe, and the width of the bracket plate 55a. Is formed so that the weld bead can be amplified as compared with the conventional case in which the weld bead is formed only by the length corresponding to the length of the weld bead.
[0022]
As shown in FIG. 7, the welding of the bracket plate 55a and the reinforcing plate 55c is one-sided groove welding, and the abutting portion between the bracket plate 55a and the upper plate 40aa is formed of a one-sided groove fillet, fillet welding, or the like. It is appropriately welded by a well-known welding method.
[0023]
With the above-described configuration, the load from the positioning cylinder 57 is first transmitted to the bracket plate 55a via the connecting pin 46, and is transmitted to the upper plate 40aa while being distributed to the reinforcing plate 55c from the middle. At this time, since the upper plate 40aa is welded over a long entire length to which the thickness of the left and right bracket plates 55a and the width of the reinforcing plate 55c are added, stress concentration is reduced even if the length of the bracket plate cannot be secured long. can do. Further, the weld bead toe 60 is substantially straight with respect to the width direction of the bracket plate 55a, and functions as an amplifying portion for increasing the width dimension of the weld bead, whereby the stress is dispersed, and the stress concentration is further increased. Be relaxed. Therefore, even if the extension distance L2 to the end of the bracket 55 cannot be secured, it is possible to prevent the occurrence of cracks and the like. Also, the other end of the reinforcing plate 55c has a concave portion at the center, and the weld 55cb with the bracket plate 55a is smoothly connected, so that stress concentration at this connecting portion can be prevented.
[0024]
Next, a modified example of the reinforcing plate in the bracket of the first embodiment will be described with reference to FIG. FIG. 8 is a sectional view corresponding to FIG. In this figure, 55c1 is a reinforcing plate. While the reinforcing plate 55c of the embodiment is groove-welded with its upper surface aligned with the inclined surface up to the end of the bracket plate 55a, the reinforcing plate 55c1 has the upper surface substantially parallel to the inclined surface and A width allowing fillet welding is provided between the bracket plate 55a and the inclined surface, and welding is performed by fillet welding which is easier than groove welding. Even with such a structure, the weld bead between the end of the bracket plate 55a and the upper plate 40aa, the weld bead between the reinforcing plate 55c1 and the upper plate 40aa, and the bead toe of each weld bead can be almost aligned. In addition, since welding on the other side of the reinforcing plate 55c1 can be formed in a concave curve shape as in the above embodiment, stress concentration can be avoided, and the same effect as in the above embodiment can be obtained.
[0025]
Further, another modified example of the reinforcing plate will be described with reference to FIG. FIG. 9 is a sectional view corresponding to FIG. In this figure, 55c2 is a reinforcing plate, the lower surface of which is overlapped with the inclined surface of the bracket plate 55a, the width of which protrudes from the outer width of the left and right bracket plates 55a, and the lower side thereof is welded by simple fillet welding. It is. Even with such a structure, the weld bead of the bracket plate 55a and the upper plate 40aa and the weld bead of the reinforcing plate 55c2 and the upper plate 40aa and / or the bead toe of each weld bead can be substantially aligned. Stress concentration can be avoided.
[0026]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 10 shows a bracket plate 65a and an amplifying section 65c integrally formed in a T-shape, and only one side of a pair of bracket plates is shown in a perspective view. 65ct is an end of the common abutting portion of the end of the bracket plate 65a and the amplifying portion 65c, and is welded to the base material over the entire length of the end 65ct, and the length of the welded portion is substantially longer than the width of the bracket plate 65a. Can be lengthened. The welding of the bracket plate and the base material other than the butted portion is performed in the same manner as described above. Also in this embodiment, the load of the bracket plate 65a can be transmitted to and received by the base material over the entire length of the amplifying portion 65c, so that the same effects as those of the first embodiment can be obtained.
[0027]
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 11 is a perspective view of the bracket. In this figure, 75a is a bracket plate, and 75c is a substantially triangular amplifying member fixed by welding to the outside near the end of the bracket plate 75a. 75at is an end of the bracket plate 65a, and 75ct is an abutting portion of the amplifying member 75c, which is substantially at the same position as the end 75at and has a length substantially perpendicular to the bracket plate 75a. Welding with the base material is performed over the entire length of the end portion 75at and the abutting portion 75ct. Also in this embodiment, the load of the bracket plate 75a can be transmitted to and received by the base material over the entire length of the end portion 75at of the bracket plate 75a and the abutting portion 75ct of the amplifying member 75c. Has the effect of
[0028]
In the embodiment described above, the shape of the end portion of the bracket plate and the shape of the abutting portion between the reinforcing plate (amplifying portion) and the upper plate are not limited to those described above. At the end of the amplifying part which increases the width dimension of the abutting part against the base material, and continuously over the entire length of the amplifying part such that the weld bead and / or both bead toes are substantially straight. Any shape may be used as long as it can be welded, and the shape of the end, the shape of the groove, or the welding method is not limited.
[0029]
【The invention's effect】
As described above, at the ends of the left and right bracket plates to be welded to the base material, an amplification portion is provided in the width direction of the bracket plate, and a welding bead is provided over a long entire length including the amplification portion. The load imposed by the bracket plate is also distributed to the amplifying part and can be transmitted and received by the base material widely, so that stress concentration is avoided and cracks occur in the weld bead even if the overall length of the bracket in the cylinder load direction is short. Can be prevented.
[Brief description of the drawings]
FIG. 1 is a perspective view of a bracket structure showing a first embodiment of the present invention.
FIG. 2 is a plan view of the bracket structure shown in FIG.
FIG. 3 is a front view of the bracket structure shown in FIG. 1;
FIG. 4 is a sectional view of the bracket of FIG. 2 taken along line YY.
FIG. 5 is a plan view of FIG. 4;
FIG. 6 is an enlarged view of a welded portion surrounded by a range X in FIG.
FIG. 7 is a sectional view taken along the line ZZ of FIG. 5;
FIG. 8 is a cross-sectional view showing a modification of the first embodiment of the present invention.
FIG. 9 is a sectional view showing another modification of the first embodiment of the present invention.
FIG. 10 is a perspective view of a bracket structure showing a second embodiment of the present invention.
FIG. 11 is a perspective view of a bracket structure according to a third embodiment of the present invention.
FIG. 12 is a front view showing a conventional working mechanism.
FIG. 13 is a front view showing another example of the conventional working mechanism.
FIG. 14 is a perspective view showing a conventional bracket structure.
15A and 15B show a conventional bracket, wherein FIG. 15A is a plan view and FIG. 15B is a front view.
[Explanation of symbols]
40aa Base materials 55a, 65a, 75a Bracket plates 55c, 65c, 75c Amplifying unit 60 Bead toe

Claims (3)

In a bracket structure of a working machine in which a pin is inserted between a pair of brackets fixed to a base material by welding means and a load of a cylinder is received by the base material via the pin and the bracket, the cylinder of each of the brackets has At the end of the bracket in the direction opposite to the extending direction, an amplifying portion is provided to increase the width dimension of the abutting portion against the base material, and a welding bead between the bracket end and the base material in this bracket is provided. A bracket structure for a working machine, wherein the bracket structure is provided so as to extend over the entire length of the amplification section. The amplifying portion is formed of a reinforcing plate provided so as to bridge between the two brackets, and the reinforcing plate is fixed to the both brackets by welding means, and the abutting portion to the base material is welded by welding means. The bracket structure for a working machine according to claim 1, wherein the bracket structure is fixed. The bracket structure for a working machine according to claim 1, wherein the reinforcing plate extends toward the cylinder mounting side to a position where the reinforcing plate does not interfere with the operation of the cylinder, and has a concave curved end.

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