JP4912783B2 - Boom sliding mechanism - Google Patents

Description

  The present invention relates to a boom sliding mechanism that enables smooth expansion and contraction of a second boom in a telescopic boom in which a second boom is telescopically fitted inside the first boom.

Multistage telescopic booms are widely used in various working machines such as cranes. In a multistage telescopic boom, a plurality of booms are telescopically combined in a telescopic manner. An example of such a multistage telescopic boom is shown in FIGS.
The work machine 100 is equipped with a folding arm 101. The bendable arm 101 has a distal end side arm 102 and a proximal end side arm 103 which are connected to bend freely.

The distal arm 102 has a box shape and includes multistage telescopic booms 105, 106, and 107. The boom 105 is positioned on the outermost side, a boom 106 is inserted into the boom 105 so as to be extendable and retractable, and a boom 107 is inserted into the boom 106 so as to be extendable.
When not in operation, the booms 106 and 107 are telescopically housed in the boom 105, and the distal arm 102 is retracted. During work, the booms 106 and 107 are pulled out, and the distal arm 102 is extended. When the front end side arm 102 is expanded and contracted, the boom 106 expands and contracts within the boom 105, and the boom 107 extends and contracts within the boom 106.
In order to facilitate the expansion and contraction of the booms 106 and 107, a sliding pad shown in FIG. 8 has been proposed (conventional example 1) (see Patent Document 1).

  The sliding pad 120 of Conventional Example 1 is a plate-shaped resin molded body and contains a fluorine-based resin. The surface of the sliding pad 120 forms a sliding surface 121. The sliding pad 120 is fixed by bolts 123 on the inner surface of the tip of the boom 105, and the sliding surface 121 of the sliding pad 120 faces the outer surface of the boom 106. Similarly, the sliding pad 120 is also fixed by bolts 123 on the inner surface of the tip of the boom 106.

A counterbore 122 penetrates from the front surface to the back surface of the sliding pad 120. The seating surface depth of the counterbore hole 122 is a depth that allows the head of the bolt 123 to be accommodated. After the bolt 123 is tightened, the head of the bolt 123 fits in the counterbore hole 122 and the head of the bolt 123 Does not protrude from the sliding surface 121.
Further, in order to facilitate the expansion and contraction of the booms 106 and 107, a sliding member device shown in FIG. 9 has been proposed (conventional example 2) (see Patent Document 2).

The sliding member device 130 of Conventional Example 2 includes a sliding pad 131, a shim 132, and a sliding pad storage member 133. The sliding pad storage member 133 has a box shape and stores the sliding pad 131 and the shim 132. The sliding pad storage member 133 is fastened to the boss 135 at the rear end of the boom 106 by a bolt 134. Similarly, the sliding member device 130 is also attached to the rear end of the boom 107.
JP-A-9-12276 Japanese Patent No. 3596640

  However, the sliding pad 120 of Conventional Example 1 has the following problems. When the distal arm 102 is repeatedly expanded and contracted, the sliding surface 121 of the sliding pad 120 is worn, eventually the head of the bolt 123 is exposed on the sliding surface 121, and the exposed head of the bolt 123 is the boom 105, 106. , 107 rub against the opposing sliding contact surfaces. As a result, the smooth expansion and contraction of the booms 106 and 107 is prevented, and the smooth expansion and contraction of the distal end side arm 102 is also prevented.

  In order to prevent the head portion of the bolt 123 from being exposed on the sliding surface 121, the thickness of the sliding pad 120 may be increased and the seating surface depth of the counterbore hole 122 may be increased. However, if the inner dimensions of the outer boom 105 are not changed as they are, the inner booms 106 and 107 must be made thinner by the increase in the thickness of the sliding pad 120. As a result, the strength of the distal arm 102 is not preferable. On the contrary, if the inner dimension of the outer boom 105 is increased, the mass of the distal arm 102 is not preferable.

  When the sliding pad 120 is fastened on the inner surface of the boom 105, the tip of the bolt 123 for fastening the sliding pad 120 inside the boom 106 protrudes from the outer surface of the boom 106. Must be prevented. When the tip of the bolt 123 protrudes from the outer surface of the boom 106, the protruding portion rubs against the sliding pad 120 fastened to the inner surface of the boom 105. As a result, the smooth expansion / contraction of the boom 106 is prevented, and the smooth expansion / contraction of the distal arm 102 is also prevented.

Increasing the thickness of the boom 106 can prevent the front end portion of the bolt 123 from protruding from the outer surface of the boom 106, but is not preferable because the mass of the front end side arm 102 increases.
The axial direction of the bolt 123 that fastens the sliding pad 120 to the booms 105 and 106 is orthogonal to the expansion and contraction direction of the booms 106 and 107. For this reason, when the booms 106 and 107 extend and contract, a shearing force acts on the bolt 123 at the boundary between the sliding pad 120 and the booms 105 and 106. In order to prevent the bolt 123 from being damaged by the shearing force, the diameter of the bolt 123 must be increased. As the diameter of the bolt 123 increases, the head of the bolt 123 also increases. As a result, the thickness of the sliding pad 120 must be increased, which is not preferable.

The sliding member device 130 of Conventional Example 2 has the following problems. When the distal arm 102 is repeatedly expanded and contracted, the sliding pad 131 is worn and thinned. The thinned sliding pad 131 is easy to come off from the sliding pad storage member 133. In particular, as shown in FIGS. 6 and 7, the distal arm 102 rotates at various angles and assumes various postures. When the distal arm 102 is turned upside down or upright, the thin sliding pad 131 easily falls off the sliding pad storage member 133. When the sliding pad 131 falls out of the sliding pad storage member 133, smooth expansion and contraction of the booms 106 and 107 is hindered.
The present invention solves the above problem, and an object of the present invention is to provide a boom sliding mechanism having a simplified structure without the need to bolt the sliding pad.

The present invention adopts the following configuration in order to solve the problem. According to a first aspect of the present invention, there is provided a boom sliding mechanism comprising: a telescopic boom in which a second boom is telescopically inserted inside the first boom; and between the first boom and the second boom. A sliding mechanism that is mounted on the inner surface of the front end of the first boom or the outer surface of the rear end of the second boom and is in sliding contact with the other surface. A pad and a mounting member that determines a mounting position of the sliding pad, and a drilling hole drilled in the sliding pad and a through hole penetrating the mounting member communicate with each other; A pin insertion hole for inserting the pin member is formed, and an axial direction of the pin member inserted into the pin insertion hole coincides with an expansion / contraction direction of the second boom , The total length) ≧ (the total length of the pin member).

  The pin member is inserted into the pin insertion hole, the tip side portion of the pin member is stored in the hole formed in the sliding pad, and the rear end side portion of the pin member is stored in the through hole of the mounting member. The sliding pad is fixed to the mounting member by the pin member. Since the sliding pad can be fixed without being fastened with bolts, there is no need to worry that the tip of the bolt protrudes outward from the first boom or the second boom, and the first boom or second It is no longer necessary to increase the thickness of the boom.

  When the second boom expands and contracts inside the first boom, the force in the expansion and contraction direction of the second boom acts on the sliding pad, and the expansion and contraction of the second boom is also applied to the pin member that fixes the sliding pad to the mounting member. Directional force works. Since the axial direction of the pin member inserted into the pin insertion hole coincides with the expansion / contraction direction of the second boom, the force acting on the pin member is the compressive force or tensile force in the axial direction of the pin member. Since no shear force acts on the pin member, the pin member can be reduced in diameter.

By using a small-diameter pin member, the thickness of the mounting member can be reduced. If the thickness of the sliding pad is reduced together with the mounting member, the entire thickness of the boom sliding mechanism can be reduced. If the thickness of the boom sliding mechanism is reduced, the gap between the first boom and the second boom is reduced, and the outer diameter of the second boom inside the first boom can be increased. The strength of can be increased.
In addition, by reducing the thickness of the mounting member, it is possible to increase the wear margin of the sliding pad and reduce the replacement frequency of the sliding pad.

In the boom sliding mechanism according to the first aspect of the invention, the entire length of the drilling hole of the sliding pad is longer than the total length of the pin member, so that the entire pin member may be pushed into the drilling hole. it can. When the worn sliding pad is replaced, the worn sliding pad can be easily removed by pushing the entire pin member into the hole formed in the sliding pad. The old pin member and the worn sliding pad can be easily put together and discarded.
When it is necessary to dispose of the old pin member and the worn sliding pad separately, if the hole diameter of the sliding pad is larger than the outer diameter of the pin member, the sliding pad can be removed. Since the pin member pushed into the perforation hole can be easily extracted, the separation process can be easily performed.

Boom sliding mechanism according to the second invention, in the boom sliding mechanism according to the first invention, the pin member is a spring pin.
The spring pin has a simple structure, is inexpensive and lightweight, and is preferable.

  Since the present invention is a boom sliding mechanism as described above, the sliding pad does not need to be bolted and has a simplified structure.

  The best mode for carrying out the present invention will be described with reference to FIGS. 1 is a perspective view of a boom sliding mechanism according to the present invention, FIG. 2 is a cross-sectional configuration diagram of the boom sliding mechanism according to the present invention, and FIG. 3 is an explanatory view of each member constituting the boom sliding mechanism according to the present invention. 3 (i) is a partial perspective view of a sliding pad, FIG. 3 (ii) is a perspective view of a mounting member, FIG. 3 (iii) is a perspective view of a spring pin, and FIG. 4 is a sliding pad replacement operation. It is explanatory drawing of. In addition, in FIG. 1, illustration of the boom 2 mentioned later is abbreviate | omitted.

  A multistage telescopic boom 1 shown in FIGS. 1 and 2 is the same as the conventional one, and has box-shaped booms 2 and 3. Each of the booms 2 and 3 has six side plates 6, and these six side plates 6 form a hexagonal column. Boom 2 forms a first boom and boom 3 forms a second boom. A boom 3 is inserted into the boom 2 in an extendable manner. The expansion / contraction direction of the boom 3 coincides with the longitudinal direction of the boom 3.

Four boom sliding mechanisms 10 are provided on the outer surface 5 of the rear end portion of the boom 3. One boom sliding mechanism 10 is provided on each of the four side plates 6 of the six side plates 6 of the boom 3.
Each boom sliding mechanism 10 includes a pair of mounting member 11, a sliding pad 18, and two spring pins 25.

  Each mounting member 11 is fixed on the side plate 6, and the mounting members 11 are arranged at a predetermined interval in the expansion / contraction direction of the boom 3. As shown in FIG. 3 (ii), the mounting member 11 has a “U” -shaped outer shape, and the “U” -shaped hollow portion forms a recess 12. The concave portions 12 of the mounting members 11 that make a pair on the side plate 6 face each other. A through hole 14 passes through the mounting member 11, and the through direction of the through hole 14 coincides with the expansion / contraction direction of the boom 3. The total length of the through hole 14 is L1. The thickness of the mounting member 11 is T1.

  The sliding pad 18 shown in FIG. 1, FIG. 2 and FIG. Protrusions 19 are formed on both ends of the sliding pad 18 in the longitudinal direction. The protrusion 19 has a shape corresponding to the recess 12 of the mounting member 11, and the protrusion 19 and the recess 12 are configured to be engageable with each other. The protrusion 19 is formed with a hole 20 having a full length L 2, and the direction of the hole 20 is the same as the longitudinal direction of the sliding pad 18. The thickness of the sliding pad 18 is T2, and the relationship of T2> T1 is established.

  The sliding pad 18 is disposed so as to be sandwiched between the paired mounting members 11, and the longitudinal direction of the sliding pad 18 coincides with the expansion / contraction direction of the boom 3. The protrusions 19 at both ends of the sliding pad 18 engage with the recesses 12 of the mounting member 11 facing each other, and the hole 20 of the protrusion 19 and the through hole 14 of the mounting member 11 communicate with each other at each engagement portion. An insertion hole 23 is formed. The direction of the pin insertion hole 23 coincides with the expansion / contraction direction of the boom 3.

Assuming that the total length of the spring pin 25 shown in FIGS. 1, 2 and 3 (iii) is L3, there are L2 between the total length L3 of the spring pin 25, the total length L1 of the through hole 14 and the total length L2 of the drilling hole 20. The relationship of ≧ L3> L1 is established.
When the spring pin 25 is inserted into the pin insertion hole 23 with a hammer or the like, the rear end side of the spring pin 25 is accommodated in the through hole 14 as shown in FIG. . The tip end portion of the spring pin 25 is also accommodated in the perforated hole 20 in the sliding pad 18, and the sliding pad 18 is not detached from the mounting member 11 by being axially fixed on both sides in the longitudinal direction.

Next, the operation will be described.
When the telescopic boom 1 performs the telescopic operation, the boom 3 expands and contracts within the boom 2. Since the sliding surface 21 of the sliding pad 18 is in sliding contact with the inner side surface 4 of the boom 2 and the sliding pad 18 contains a fluororesin, the boom 3 can be expanded and contracted smoothly.
When the boom 3 expands and contracts, a force in the expansion / contraction direction of the boom 3 acts on the sliding surface 21 of the sliding pad 18 from the inner side surface 4 of the boom 2. Since the axial direction of the spring pin 25 coincides with the expansion / contraction direction of the boom 3, the force acting on the spring pin 25 when the boom 3 expands / contracts is an axial compression force or tensile force. No shear force acts on the spring pin 25 at the boundary between the drill hole 20 and the through hole 14 in the pin fitting hole 23.

  Since the spring pin 25 has a large strength against the compressive force or tensile force in the axial direction, the diameter of the spring pin 25 can be reduced. If the diameter of the spring pin 25 is reduced, the thickness T1 of the mounting member 11 can be reduced. If the thickness T1 of the mounting member 11 is reduced and the thickness T2 of the sliding pad 18 is also reduced, the overall thickness of the boom sliding mechanism 10 can be reduced. If the entire thickness of the boom sliding mechanism 10 is reduced, the gap between the boom 2 and the boom 3 can be narrowed, so that the boom 3 inside the boom 2 can be thickened and the strength of the telescopic boom 1 can be increased. it can.

Further, only the thickness T1 of the mounting member 11 can be reduced to increase T2-T1, which is the wear allowance of the sliding pad 18, and the replacement frequency of the sliding pad 18 can be reduced.
When the boom 3 repeatedly expands and contracts, the sliding pad 18 is worn, and the thickness of the sliding pad 18 approaches the thickness T1 of the mounting member 11, the worn sliding pad 18 is replaced with a new sliding pad 18. .

  First, the spring pin 25 in the pin insertion hole 23 is pushed into the deepest hole 20 of the sliding pad 18 (see FIG. 4). Since (the total length L2 of the drilling hole 20) ≧ (the total length L3 of the spring pin 25), the entire spring pin 25 is accommodated in the drilling hole 20, and the sliding pad 18 can be easily placed between the mounting members 11. Can be removed from. When the worn sliding pad 18 is removed, a new sliding pad 18 is installed between the mounting members 11, and a new spring pin 25 is fitted into the pin fitting hole 23 to fix the new sliding pad 18.

Since the old spring pin 25 is stored in the drilled hole 20 of the worn sliding pad 18, the spring pin 25 and the worn sliding pad 18 can be discarded together.
When it is necessary to discard the old pin member 25 and the worn sliding pad 18 separately, if the hole diameter of the hole 20 of the sliding pad 18 is made larger than the outer diameter of the pin member 25, When the moving pad 18 is removed, the pin member 25 pushed into the perforation hole 20 can be easily extracted, so that the separation process can be easily performed.

In the present embodiment, a relationship of L2 ≧ L3> L1 is established between the total length L3 of the spring pin 25, the total length L1 of the through hole 14, and the total length L2 of the drilled hole 20, but instead The configuration shown in the modification of FIG. 5 can be adopted.
In the boom sliding mechanism 10 according to the modification of FIG. 5, a relationship of L1 + L2 <L3 is established between the total length L3 of the spring pin 25, the total length L1 of the through hole 14, and the total length L2 of the drilling hole 20. .

The spring pin 25 that is inserted into the pin insertion hole 23 and fixes the sliding pad 18 is pushed from the beginning to the innermost end of the hole 20 of the sliding pad 18. A part on the rear end side protrudes outward from the pin fitting hole 23. When exchanging the worn sliding pad 18, the worn sliding pad 18 can be easily removed by pinching and pulling out the portion protruding from the pin fitting hole 23 of the spring pin 25 with pliers or the like.
In this embodiment, the boom sliding mechanism 10 is provided on the outer side surface 5 of the rear end portion of the boom 3. Instead, the boom sliding mechanism 10 is provided on the inner side surface 4 of the tip end portion of the boom 2. It is good also as providing in.

It is a perspective view of the boom sliding mechanism which concerns on this invention. It is a section lineblock diagram of a boom sliding mechanism concerning the present invention. It is explanatory drawing of each member which comprises the boom sliding mechanism which concerns on this invention, FIG.3 (i) is a fragmentary perspective view of a sliding pad, FIG.3 (ii) is a perspective view of a mounting member, FIG.3 (iii) FIG. 3 is a perspective view of a spring pin. It is explanatory drawing of the replacement | exchange operation | work of a sliding pad. It is a fragmentary sectional block diagram of the boom sliding mechanism which concerns on a modification. It is explanatory drawing of the state which the conventional working machine extended the arm. It is explanatory drawing of the state which the conventional working machine bent the arm. It is a block diagram of the sliding pad which concerns on the prior art example 1. FIG. It is a block diagram of the sliding member apparatus which concerns on the prior art example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Telescopic boom 2, 3 Boom 4 Inner side surface 5 Outer side surface 6 Side plate 10 Boom sliding mechanism 11 Mounting member 12 Recessed part 13 End surface 14 Through hole 18 Sliding pad 19 Protrusion 20 Drilling hole 21 Sliding surface 23 Pin insertion hole 25 Spring pin L1 Total length of through hole L2 Total length of drilled hole L3 Total length of spring pin T1 Thickness of mounting member T2 Thickness of sliding pad

Claims (2)

In a telescopic boom in which a second boom is telescopically inserted inside the first boom, a boom sliding mechanism provided between the first boom and the second boom. ,
A sliding pad that is attached to the inner side surface on the front end side of the first boom or the outer side surface on the rear end side of the second boom, and is in sliding contact with the other surface;
A mounting member for determining a mounting position of the sliding pad,
A pin fitting insertion hole into which a pin member is fitted is formed by communicating a drilling hole drilled in the sliding pad and a through hole penetrating the mounting member.
The axial direction of the pin member inserted into the pin insertion hole matches the expansion / contraction direction of the second boom ,
A boom sliding mechanism having a relationship of (total length of the drilled hole) ≧ (total length of the pin member) . The boom sliding mechanism according to claim 1 , wherein the pin member is a spring pin.

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