JP4625589B2 - Work vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a work vehicle .
[0002]
[Prior art]
For example, a conventional work vehicle represented by a hydraulic excavator as disclosed in Japanese Patent Laid-Open No. 6-220882, for example, has a base end portion of a boom 1 connected to a vehicle body 20 in a undulating manner as shown in FIG. The arm 40 for connecting the bucket 30 to the tip is connected to perform excavation work, so-called backhoe work. The boom has a cross-sectional box shape having a lower wall 103, an upper wall 104, a left wall 105, and a right wall 106 as in the boom 101 shown in FIG. .
[0003]
In such a boom 101, as shown in FIG. 15, a load is applied so as to extend the “b” -shaped middle bent portion 102 during excavation work, and tensile stress is applied to the lower wall 103 and compression is applied to the upper wall 104. You will be stressed. In particular, stress concentration tends to occur on the lower wall 103 in the vicinity of the midway bent portion 102, and excessive tensile stress tends to cause cracking of the material. Therefore, it is required to ensure the strength of the mid-bent portion so that the boom can withstand the stress generated even when the load is repeatedly applied, particularly the tensile stress.
[0004]
[Problems to be solved by the invention]
Therefore, there is a boom having a structure in which a reinforcing member is provided at a mid-bend portion or a wall of the mid-bend portion is thickened to disperse stress and enhance strength. However, when the strength of the mid-bend portion is increased by such means, the cost and the weight are increased.
[0005]
In view of such various problems, the present invention can improve the durability by reducing the tensile stress applied to the member (the lower wall 103 in the above example) serving as the outer wall of the boom, or reduce the cost. An object of the present invention is to provide a work vehicle that can be reduced in weight.
[0006]
[Means for solving the problems and effects]
In order to solve the above problem, a work vehicle according to an aspect of the present invention is a backhoe-type work vehicle, and is supported by a first support portion provided at a base end portion so as to be raised and lowered, and provided at a distal end portion. A boom is provided that supports the work tool in a undulating manner at the support portion, and the first member, which is the lower wall of the boom , is assembled in a state of receiving a compressive stress.
[0007]
In order to solve the above problem, a work vehicle according to another aspect of the present invention is a front shovel type work vehicle, and is supported in a undulating manner at a first support portion provided at a base end portion. A boom that supports the work tool in a undulating manner is provided in the second support portion that is provided, and the first member that is the upper wall of the boom is assembled in a state of receiving a compressive stress.
[0008]
Further, in the work vehicle described above, the boom includes a second member that applies compressive stress to the first member, and hopefully both ends of the second member are provided at the base end portion of the boom, respectively. It is desirable that the first support portion and the second support portion provided at the tip end portion are fixed to each other.
[0009]
Furthermore, in the manufacturing method for manufacturing the boom having the above structure, the second member is coupled with the first member in an elastically deformed state by applying an external force, and the second member is deformed by removing the external force after the coupling. It is desirable to apply a compressive stress to the first member by this restoring force.
[0010]
According to the work vehicle described above, a compressive stress can be generated in the first member in advance by the elastic restoring force of the internal member. For this reason, even if a force is applied to the boom by excavation work and a tensile stress is generated in the first member, the tensile stress is reduced by a pre-existing compressive stress, so the maximum value of the tensile stress generated in the first member is reduced. The Therefore, the life and durability of the boom can be improved without using means for increasing the cost and weight, such as increasing the thickness or adding a reinforcing member.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a boom structure for a work vehicle and a method for manufacturing the same according to the present invention will be described in detail with reference to the drawings. The external shape of the boom and the mounting of the boom to the vehicle body are the same as in the prior art. That is, as shown in the longitudinal sectional view of FIG. 2, the boom 1 of the present embodiment has a cross-sectional box shape having a lower wall 3, an upper wall 4, a left wall 5, and a right wall 6. As shown in FIG. 1, the base end portion is connected to the vehicle body 20 so as to be raised and lowered, and the arm 40 for connecting the bucket 30 is connected to the distal end portion.
[0012]
As shown in FIG. 2 and FIG. 3, which is a side sectional view of the boom 1, the boom 1 has a beam-shaped internal member 10 bent in a “<” shape in the side view. 11, 12, 13, 14, and 15 are provided with a hole 16 that is substantially the same as the inner member in order to guide the inner member 10, so that the lower wall 3, the upper wall 4, the left wall 5, and the right wall 6 It is a plate interposed between them. The plates 11, 12, 13, 14, 15 are arranged at intervals in the longitudinal direction of the internal member 10. The plates 11, 12, 13, 14, 15 are not displaced in the longitudinal direction with respect to the internal member 10, and the surfaces of the plates 11, 12, 13, 14, 15 are substantially normal to the lower wall 3 and the upper wall 4. Restrain to the direction. (It may be fixed to the internal member 10)
When the internal member 10 is deformed, the plates 11, 12, 13, 14, and 15 are brought into contact with the lower wall 3, the upper wall 4, the left wall 5, or the right wall 6 to transmit the force in the deformation direction of the internal member 10, 3. The upper wall 4, the left wall 5, and the right wall 6 are deformed in the same direction as the internal member 10. The plates 11, 12, 13, 14, and 15 may be divided, and the number of plates is not limited to five. Further, the internal member 10 does not have to have a circular cross section as shown in FIG.
[0013]
The manufacturing process of a boom is shown in FIGS. First, as shown in FIG. 4, a first support portion 7 having a pin hole for attaching the boom 1 to the vehicle body 20 at the proximal end portion of the internal member 10, and a pin for attaching the arm 40 to the boom 1 at the distal end portion. The 2nd support part 8 which has a hole is each attached. Each of the first support portion 7 and the second support portion 8 has a flat portion on one end side, and one end side and the other end side of the internal member 10 are inserted into each flat portion. Here, the interval between the pin holes of the first support portion 7 and the second support portion 8 at the time of attachment to the internal member 10 is L0.
[0014]
Next, as shown in FIG. 5, the internal member 10 is expanded by applying an external force with a molding machine or the like. However, this extension is within the range of elastic deformation. As the internal member 10 expands, the distance between the pin holes of the first support part 7 and the second support part 8 increases from L0 to L1 (> L0).
[0015]
Then, as shown in FIG. 6, the inner member 10 is restrained while being extended, and the lower wall 3 is assembled on the lower side of the inner member 10, the upper wall 4 on the upper side, the left wall 5 on the left side, and the right wall 6 on the right side. . The lower wall 3, the upper wall 4, the left wall 5, and the right wall 6 are welded to each other at adjacent edges, and both end portions thereof are welded to the first support portion 7 and the second support portion 8.
[0016]
When the restraint is released from the above state, as shown in FIG. 7, the internal member 10 tends to deform in the bending direction by elastic restoration. However, the deformation of the internal member 10 in the bending direction simultaneously transmits the force through the plates 11, 12, 13, 14, 15, the first support portion 7 and the second support portion 8, and the lower wall 3 and the upper wall 4. The left wall 5 and the right wall 6 are deformed in the bending direction. For this reason, the internal member 10 receives the force in the extending direction due to the elastic restoration of the lower wall 3, the upper wall 4, the left wall 5 and the right wall 6, and therefore does not return to the state described with reference to FIG. 4. That is, at a position where the force in the bending direction due to the elastic restoration of the internal member 10 and the force in the extending direction due to the elastic restoration of the lower wall 3, the upper wall 4, the left wall 5 and the right wall 6 are balanced. The deformation in the bending direction stops. At this time, the space | interval of each pin hole of the 1st support part 7 and the 2nd support part 8 narrows from L1 to L2. The expression “L1>L2> L0” is established between L0, L1, and L2.
[0017]
Since the boom 1 of this embodiment is assembled as described above, a compressive stress is generated in the lower wall 3 in advance by a force in the bending direction due to the elastic restoration of the internal member 10 itself. For this reason, even if a force in the extending direction is applied to the boom 1 by excavation work and a tensile stress is generated in the lower wall 3, the tensile stress is reduced by the pre-existing compressive stress. The maximum value is reduced. Therefore, the life and durability of the lower wall 3 can be improved without using means for increasing the cost and weight, such as increasing the thickness of the lower wall 3 or adding a reinforcing member.
[0018]
In addition, when the bucket 30 is inverted and attached to the configuration shown in FIG. 1 and used as a front shovel, a load is applied so as to further bend the “B” -shaped mid-bend portion of the boom 1 during excavation work. A tensile stress is generated on the upper wall 4 and a compressive stress is generated on the lower wall 3. In this case, if the lower wall 3, the upper wall 4, the left wall 5, and the right wall 6 are assembled while the inner member 10 is elastically deformed by applying a force in the bending direction, the inner member 10 is elastically restored. Thus, a force in the extending direction is applied to the lower wall 3, the upper wall 4, the left wall 5 and the right wall 6. Therefore, compressive stress is generated in the upper wall 4 in advance, and the maximum value of tensile stress generated in the upper wall 4 during excavation work is reduced. Therefore, the life and durability of the upper wall 4 can be improved.
[0019]
Next, another embodiment of a boom structure for a work vehicle and a method for manufacturing the same according to the present invention will be described in detail with reference to FIGS. The external shape of the boom and the mounting of the boom to the vehicle body are the same as in the prior art. That is, as shown in the longitudinal sectional view of FIG. 8, the boom 1A of the present embodiment has a cross-sectional box shape having a lower wall 3A, an upper wall 4A, a left wall 5A, and a right wall 6A. 1, and the base end portion is connected to the vehicle body 20 in a undulating manner, and the arm 40 for connecting the bucket 30 is connected to the distal end portion, similarly to the embodiment shown in FIG. Yes.
[0020]
As shown in FIG. 8 and FIG. 9, which is a side sectional view of the boom 1A, the boom 1A has a plate 11A interposed between the lower wall 3A, the upper wall 4A, the left wall 5A, and the right wall 6A. , 12A, 13A, 14A, 15A plates. The plates 11A, 12A, 13A, 14A, and 15A are arranged at intervals in the longitudinal direction of the boom 1A. The plates 11A, 12A, 13A, 14A, and 15A are constrained so that the surfaces of the plates 11A, 12A, 13A, 14A, and 15A are substantially normal to the lower wall 3A and the upper wall 4A. The plates 11A, 12A, 13A, 14A, 15A may be divided, and the number of plates is not limited to five.
[0021]
10 to 13 show a boom manufacturing process. First, as shown in FIG. 10, a first support portion 7A having a pin hole for attaching the boom 1A to the vehicle body 20 at the base end portions of the left wall 5A and the right wall 6A, and an arm 40 on the boom 1A at the distal end portion. 8 A of 2nd support parts which have a pin hole for attachment are each attached. The plates 11A, 12A, 13A, 14A, and 15A are attached to the left wall 5A and the right wall 6A, respectively. Here, the interval between the pin holes of the first support portion 7A and the second support portion 8A at the time of attachment to the left wall 5A and the right wall 6A is L0.
[0022]
Next, as shown in FIG. 11, the left wall 5A and the right wall 6A are extended by applying an external force with a molding machine or the like. However, this extension is within the range of elastic deformation. By extending the left wall 5A and the right wall 6A, the distance between the pin holes of the first support portion 7 and the second support portion 8 is increased from L0 to L1 (> L0).
[0023]
Then, as shown in FIG. 12, the left wall 5A and the right wall 6A are restrained while being extended, and the lower wall 3A is assembled to the lower side of the left wall 5A and the right wall 6A, and the upper wall 4A is assembled to the upper side. The lower wall 3A, the upper wall 4A, the left wall 5A and the right wall 6A are welded together at adjacent edges, and both end portions of the lower wall 3A and the upper wall 4A are the first support portion 7A and the second support portion 8A. Welded to.
[0024]
When the restraint is released from the above state, as shown in FIG. 13, the left wall 5A and the right wall 6A tend to deform in a direction in which the first support portion 7A and the second support portion 8A approach each other due to elastic recovery. However, the deformation of the left wall 5A and the right wall 6A in the direction in which the first support portion 7A and the second support portion 8A approach each other simultaneously includes the plates 11A, 12A, 13A, 14A, 15A, the first support portion 7A, and the second support portion. Force is transmitted through the portion 8A, and the lower wall 3A and the upper wall 4A are deformed in a direction in which the first support portion 7A and the second support portion 8A approach each other. For this reason, the left wall 5A and the right wall 6A receive the force in the direction in which the first support portion 7A and the second support portion 8A are separated by the elastic recovery of the lower wall 3A and the upper wall 4A, and thus return to the state described in FIG. There is nothing. That is, the force in the direction in which the first support portion 7A and the second support portion 8A approach due to the elastic recovery of the lower wall 3A and the upper wall 4A itself, and the first support portion 7A and the first support due to the elastic recovery of the lower wall 3A and the upper wall 4A. The deformation in the direction in which the first support portion 7A and the second support portion 8A of the left wall 5A and the right wall 6A approach is stopped at the position where the force in the direction in which the two support portions 8A are separated from each other. At this time, the space | interval of each pin hole of 7 A of 1st support parts and 8 A of 2nd support parts narrows from L1 to L2. The expression “L1>L2> L0” is established between L0, L1, and L2.
[0025]
Since the boom 1A of the present embodiment is assembled as described above, the lower wall 3A is preliminarily provided by the force in the direction in which the first support portion 7A and the second support portion 8A approach due to the elastic recovery of the left wall 5A and the right wall 6A itself. Compressive stress is generated in For this reason, even if a force in the extending direction is applied to the boom 1A due to excavation work and a tensile stress is generated in the lower wall 3A, the tensile stress is reduced by the pre-existing compressive stress, so the tensile stress generated in the lower wall 3A is reduced. The maximum value is reduced. Therefore, the life and durability of the lower wall 3A can be improved without using means for increasing the cost and weight, such as increasing the thickness of the lower wall 3A or adding a reinforcing member.
[0026]
Further, when the bucket 30 is inverted and attached to the form shown in FIG. 1 and used as a front shovel, a load is applied so as to further bend the “B” -shaped mid-bend portion of the boom 1A during excavation work. A tensile stress is generated on the upper wall 4A, and a compressive stress is generated on the lower wall 3A. In this case, the lower wall 3A and the upper wall 4A can be assembled with the left wall 5A and the right wall 6A being elastically deformed by applying a force in the direction in which the first support portion 7A and the second support portion 8A approach. For example, the left wall 5A and the right wall 6A apply a force in the direction in which the first support portion 7A and the second support portion 8A are separated from the lower wall 3 and the upper wall 4 by elastic restoration. Therefore, compressive stress is generated in advance on the upper wall 4A, and the maximum value of tensile stress generated in the upper wall 4A during excavation work is reduced. Therefore, the life and durability of the upper wall 4A can be improved.
[0027]
As described above with reference to the embodiment, according to the boom structure and the manufacturing method thereof of the present invention, it is possible to generate a compressive stress in advance on any constituent member of the boom by the elastic restoring force of the internal member itself. it can. For this reason, even if a force is applied to the boom by excavation work and a tensile stress is generated in the component member, the tensile stress is reduced by a pre-existing compressive stress, so the maximum value of the tensile stress generated in the component member is reduced. . Therefore, the life and durability of the boom can be improved without using means for increasing the cost and weight, such as increasing the thickness or adding a reinforcing member.
[Brief description of the drawings]
FIG. 1 is a diagram of a work vehicle having a boom according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of a boom according to an embodiment of the present invention.
FIG. 3 is a side sectional view of the boom according to the embodiment of the present invention.
FIG. 4 is a first explanatory diagram of a boom manufacturing process according to the embodiment of the present invention.
FIG. 5 is a second explanatory diagram of a boom manufacturing process according to the embodiment of the present invention.
FIG. 6 is a third explanatory diagram of the boom manufacturing process according to the embodiment of the present invention.
FIG. 7 is a fourth explanatory diagram of the boom manufacturing process according to the embodiment of the present invention.
FIG. 8 is a longitudinal sectional view of a boom according to another embodiment of the present invention.
FIG. 9 is a side sectional view of a boom according to another embodiment of the present invention.
FIG. 10 is a first explanatory view of a boom manufacturing process according to another embodiment of the present invention.
FIG. 11 is a second explanatory diagram of a boom manufacturing process according to another embodiment of the present invention.
FIG. 12 is a third explanatory diagram of a boom manufacturing process according to another embodiment of the present invention.
FIG. 13 is a fourth explanatory diagram of a boom manufacturing process according to another embodiment of the present invention.
FIG. 14 is a longitudinal view of a boom according to the prior art.
FIG. 15 is a side view of a conventional boom.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,1A ... Boom, 3, 3A ... Lower wall, 7, 7A ... 1st support part, 8, 8A ... 2nd support part, 10 ... Internal member.

Claims (4)

A backhoe type work vehicle,
A boom that is supported by the first support portion provided at the base end portion so as to be raised and lowered, and that supports the work tool at the second support portion provided at the distal end portion ;
A work vehicle in which a first member, which is a lower wall of a boom (1) , is assembled in a state of receiving a compressive stress.   A front shovel type work vehicle,
  A boom that is supported by the first support portion provided at the base end portion so as to be raised and lowered, and that supports the work tool at the second support portion provided at the distal end portion;
  A work vehicle characterized in that the first member (3), which is the upper wall of the boom (1), is assembled in a state of receiving a compressive stress. Work vehicle in the working vehicle according to claim 1 or 2, the boom (1), characterized in the second member (10) that incorporates a give a compressive stress to the first member (3). The work vehicle according to claim 3 , wherein both ends of the second member (10) are respectively provided at a base end portion of the boom (1) and a second support portion provided at a distal end portion. (8) Work vehicle characterized by being fixed to.

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