JP4760960B2 - Boom and slide support member for boom - Google Patents

Description

  The present invention relates to a telescopic boom used in a construction machine such as a crane, and a boom slide support member that is provided between inner and outer boom members constituting the boom and slidably supports an inner boom member.

  The background art will be described taking a four-stage (three-stage telescopic) boom as an example.

  As shown in FIG. 7, this boom is telescope-like with each of the first to fourth cylindrical boom members 1 to 4 (indicated by bold lines) in order from the base end side attached to the base machine of the machine. It is configured to be extendable and retractable.

  Further, as a kind of boom members 1 to 4 constituting the telescopic boom, the lower portion in the horizontal state of the boom as shown in FIG. Those having a U-shaped curved cross-sectional shape are used. Hereinafter, such a boom material having a curved lower portion may be referred to as a curved boom material, and a boom used therefor may be referred to as a curved boom.

  Note that the top wall of each boom member 1 to 4 in the horizontal state of the boom and both side walls extending downward from the top wall are flat (flat), and the lower part from the side walls to the bottom wall is It has a curved shape as described above.

  Strictly speaking, the lower portions of the curved boom members 1 to 4 are formed into a polygonal shape by bending a flat plate a plurality of times, and are macroscopically curved.

  In this curved boom, like other telescopic booms, pads 5 are provided between adjacent inner and outer boom members in order to reduce sliding resistance (friction) between the inner and outer boom members particularly under load. It is done.

  The pads 5 are generally formed in a curved band shape corresponding to the boom material as shown in the figure, and at the distal end portion of the outer boom material that is particularly subjected to a large load in the lifted state, It is mounted over a certain range of direction.

  However, such integrated pads 5... Are disadvantageous in terms of mass productivity and cost because a plurality of types of pads having different curved shapes (curvature radii) are prepared for each cross-sectional shape of the boom material.

  On the other hand, in order to solve this problem, as shown in Patent Document 1, a unit pad (divided pad) in which the integrated pad is divided into a plurality of parts in the boom circumferential direction is used, and each pad is arranged outside. A technique (hereinafter, referred to as a known technique 1) for attaching the boom material to the inner circumferential surface in a circumferential direction is known.

  Further, in Patent Document 2, as an integrated improvement technique, a plurality of strips extending in the boom length direction on the upper surface (surface facing the inner boom member) side of the belt-shaped pad so as to assist the bending of the pad into a curved shape. A technique (hereinafter, referred to as “Prior Art 2”) is shown in which the folding grooves are provided at regular intervals in the circumferential direction so that the entire pad can be bent according to the cross-sectional shape of the boom material.

JP 2005-255337 A JP 2008-265980 A

  However, according to the known technique 1 (split type pad), each unit pad is fixed individually in the boom circumferential direction and the boom length direction with respect to the inner circumferential surface of the outer boom member. Even if the pad rows are fixed together by restraining them from both sides in the circumferential direction, there are the following problems.

  That is, the individual fixing method makes the work extremely complicated. Further, in the collective fixing method, since the pads are not fixed until the fixing members on both sides are mounted, the work efficiency is deteriorated after all.

  On the other hand, according to the known technique 2 (integrated pad), since the pad is a series of integrated strips, the pad thickness is constant over the entire length (length in the boom circumferential direction).

However, as a real problem,
(B) Depending on the boom, the gap between the boom members may be different in each part in the boom circumferential direction (for example, the gap may be relatively wide on both sides in the circumferential direction and narrow in the middle).
(B) Even in the case of a boom manufactured so that the gap between the boom members is uniform in the circumferential direction, the gap may vary due to manufacturing errors of both the inner and outer boom members. Then, there is a possibility that the pad cannot be fitted to the outer peripheral surface of the inner boom member.

  Thus, the present invention solves the problems 1 and 2 of the known art, improves the efficiency of the work of assembling the pad to the boom material, and keeps the pad inside even if there is a circumferential change or variation in the gap between the boom materials. The present invention provides a boom and a boom slide support member that can be surely fitted to the outer peripheral surface of the boom member.

  The invention according to claim 1 (boom slide support member) is a telescopic boom configured such that a plurality of boom members whose lower portions in a horizontal state of the boom are curved downwardly are fitted in a telescope shape inside and outside. A slide support member for a boom to be used, which is a belt-like pad holder attached to at least a lower inner peripheral surface of an outer boom member among adjacent inner and outer boom members over a certain range in the boom circumferential direction, and an inner boom member A plurality of pads that slidably support the boom member in contact with the outer peripheral surface of the pad, and the pad holder includes means for assisting bending of the pad holder into a curved shape on the upper surface side facing the inner boom member. As shown, a plurality of folding grooves that open upward and extend in the boom length direction are provided at intervals in the boom circumferential direction, and the four circumferences are closed at a portion between the folding grooves. A plurality of recesses are provided to open upward, in which is mounted in a state where the respective pad is fixed in position fitted into the recess in the boom circumferential direction and in the length direction.

  According to a second aspect of the present invention, in the configuration of the first aspect, a bending auxiliary groove that opens downward and extends in the boom length direction is provided at a position corresponding to each of the bending grooves on the lower surface side of the pad holder. It is.

According to a third aspect of the present invention, in the configuration of the first or second aspect, the pad holder and the pad are formed of different synthetic resin materials.

According to a fourth aspect of the present invention, in the configuration of the third aspect, the pad is compared with the pad holder,
(I) a small coefficient of dynamic friction;
(Ii) the difference between the coefficient of static friction and the coefficient of dynamic friction is small;
(Iii) It satisfies at least one condition of high wear resistance.

According to a fifth aspect of the present invention, in the configuration of the third or fourth aspect, the pad is formed of an oil- containing synthetic resin material .

According to a sixth aspect of the invention, in the construction of the claims 1-5, said pad holder, with a thermoplastic resin material, in advance, into a curved shape corresponding to the inner peripheral surface of the outer boom member is attached target It has been thermoformed .

A seventh aspect of the present invention is the configuration according to any one of the first to sixth aspects, wherein each of the pads is detachably fitted into the concave portion of the pad holder .

The invention of claim 8, in the configuration of claim 7, the bottom surface of the recess in Pas head holder, those pads extraction hole penetrating the pad holder thickness direction was found provided.

The invention (boom) of claim 9 is a telescopic boom constructed by fitting a plurality of boom members whose bottom portions in the horizontal state of the boom are curved downwardly into a convex shape inside and outside. The slide support member according to any one of claims 1 to 8 and a pad holder of the slide support member are fixed in a boom circumferential direction and a boom length direction at least at a lower portion of the outer boom material among the both-side boom materials. Holder fixing means is provided.

The inventions of claim 10, in the configuration of claim 9, as the holder fixing means, a front fixing member detachably attached to the distal end portion of the outer boom member in a state of restraining the pad holder from the front side, the pad A rear-side fixing member attached to the inner peripheral surface of the outer boom material in a state where the holder is constrained from the rear side at a plurality of locations in the boom circumferential direction, and an outer boom material in a state where the pad holder is constrained from both sides in the boom circumferential direction. And a circumferential fixing member attached to the inner peripheral surface .

  According to the boom and the boom slide support member of the present invention, since the plurality of pads are fitted in the recesses of the band-shaped pad holder and arranged in parallel in the boom circumferential direction, first, for example, only the pad holder is claimed. By fixing the positions of the outer boom material in the boom circumferential direction and the length direction with the holder fixing means 10 and 11, all the pads can be fixed at the same time.

  For this reason, as compared with the known technique 1 (split pad), the assembly work of the pad is simplified.

Secondly, since the pad is fitted into the recessed part whose four sides are closed, there is no possibility that the pad falls off due to the sliding contact resistance with the inner boom member.

  Thirdly, unlike the known technique 2, the pad thickness can be freely selected for each pad. Therefore, the gap between the boom members is different in each part in the boom circumferential direction, or the gap due to the manufacturing error of both the inner and outer boom members. Even if there is a variation, it is possible to fit all the pads to the outer peripheral surface of the inner boom member by selecting a pad having a thickness corresponding to the gap.

  In this case, it is assumed that the pad holder is fitted to the inner peripheral surface of the outer boom member. In this regard, according to the present invention, a plurality of bending grooves that open upward and extend in the boom length direction are provided in the portion between the recesses on the upper surface side of the pad holder as a means for assisting bending of the holder into a curved shape. Therefore, the pad holder can be easily bent according to the inner peripheral surface of the outer boom member and can be securely fitted.

  In this way, the problems 1 and 2 of the known art can be solved at the same time, and both the workability of assembling the pad and the improvement of the pad performance of helping the boom material slide can be achieved.

  Further, according to the invention of claim 2, since the groove (folding auxiliary groove opening downward) is also provided on the lower surface side of the pad holder, in order to avoid a decrease in strength particularly compared to the case where this auxiliary groove is not provided. Even when the folding groove is shallow, the pad holder can be easily bent and can be easily fitted to the inner peripheral surface of the outer boom member.

According to the inventions of claims 3 to 5 , since the pad holder and the pad are formed of different synthetic resin materials, an appropriate material can be used according to each role.

  That is, since the pad is a sliding member for assisting the sliding of the inner boom member, the sliding performance (a constant sliding performance is maintained for a long time) as compared with the pad holder that only holds the pad. It is desirable to use a synthetic resin material having good wear resistance for maintenance over a long period of time.

According to our experiments, in the range of 180 kgf / cm @ 2 extremes surface pressure is the use environment of the pads in the boom crane from 90 Kg / cm @ 2, the static friction coefficient of about 0.15, the coefficient of dynamic friction of about 0. Those satisfying the condition of 1 (difference between both friction coefficients of 0.05) were suitable for ensuring good sliding performance.

Specifically, as in the invention of claim 5, an oil-containing synthetic resin excellent in lubricity, particularly an oil-containing polyamide-based resin and an oil-containing polyacetal-based resin are preferable.

  On the other hand, the pad holder preferably has sufficient strength and hardness to support the load received through the pad, ease of bending (flexibility), and tenacity that does not break even when folded. Furthermore, it is desirable to use a synthetic resin material that is as cheap as possible even if the sliding performance is low. Specifically, a polyamide-based resin is preferable.

  In addition, when using a synthetic resin material that satisfies the conditions (i) and (ii) among the conditions of claim 4, there is no so-called squeak, especially when the boom material is caught and moved intermittently at the beginning of boom expansion and contraction. Start is smooth.

By the way, in the present invention, the pad holder is formed by bending a flat plate shaped in a belt shape into a curved shape so as to match the cross-sectional shape of the boom material. As a specific pattern regarding this bending,
(A) Pattern to bend in a state where the bending groove is made shallower and softened by heating in order to avoid the strength reduction of the pad holder,
(B) The pattern can be selected from two patterns of deep bending grooves so that bending is possible even in an unheated state, and bending at room temperature.

The pattern (a) is particularly suitable for the case of bending into a curved shape corresponding to the inner peripheral surface of the outer boom material to be attached at the manufacturing stage as in the invention of claim 6 . Moreover, it is also possible to perform the adjustment bending on the condition that it is heated by a simple heating means such as blowing hot air at the stage of assembling to the boom.

  Therefore, the pattern (a) requires the pad holder to be molded from a thermoplastic resin.

  In other words, when a thermoplastic resin material is used, the groove is made shallow so that the strength of the pad holder does not drop, and heating is used as a condition so that it matches the cross-sectional shape of the actual boom material at the manufacturing stage and bending process. Thus, the efficiency of the bending work when adjusting the curvature is improved.

  On the other hand, the pattern (b) is disadvantageous in terms of strength, but can be bent with other than thermoplastic resin, and can be bent at the assembly stage.

According to the invention of claim 7, 8, to fit removably each pad against the recess of the pad holder, the wear of the pad, it is easy to replace when damaged.

In this case, it is desirable to press-fit the pad into the recess so that the pad does not easily fall off and can be securely fixed in the boom circumferential direction and the length direction. It becomes difficult. In this regard, according to the invention of claim 8 , the pad can be easily protruded by inserting the protrusion rod into the pad extraction hole from the back side.

It is a perspective view of the boom and slide support member concerning an embodiment of the present invention. It is an expansion perspective view before the assembly of a slide support member. It is a perspective view of the assembly state of a slide support member. It is a fragmentary sectional view in the state where the slide support member was assembled to the boom. FIG. 5 is a partially enlarged view of FIG. 4. FIG. 6 is a sectional view taken along line VI-VI in FIG. 5. It is a side view of the boom used as the application object of the present invention. It is sectional drawing of the conventional boom with a slide support member.

  An embodiment of the present invention will be described with reference to FIGS.

  The slide support member of the present invention can be provided between all adjacent boom members in the telescopic bending boom (the inner peripheral surface of the distal end portion of the outer boom member).

  In the embodiment, among these, the first-stage boom material (outer boom material) 1 and the second-stage boom material (inner boom material; the third-stage boom material 3) in the four-stage boom shown in FIGS. The case where the slide support member 11 is provided at the lower end on the tip side of the first-stage boom material 1 will be described as an example.

The slide support member 11 is attached to the inner circumferential surface of the lower part of the first stage (outer) boom member 1 over a certain range in the boom circumferential direction, and is attached to the pad holder 12 and secondly attached. And a plurality of pads 13 for slidably supporting the step (inner) boom member 2.

  The pad holder 12 is formed by bending a flat plate material formed in a belt shape into a curved shape so as to fit the inner peripheral surface of the first-stage boom material 1.

  Here, the pad holder 12 is provided with a plurality of bent grooves 14 that open upward and extend in the boom length direction on the upper surface side facing the second-stage boom member 2 at intervals in the boom circumferential direction. The curved pad holder 12 is formed by curving the flat plate material in a direction in which the opening of the bent grooves 14 is closed.

  In this case, if the folding grooves 14 are relatively deep, the folding becomes easy, and if the folding grooves 14 are shallow, the folding becomes difficult. However, if the depth is increased, the strength of the pad holder 12 is decreased, and if the depth is decreased, a decrease in strength can be avoided.

  Therefore, it is possible to select from the following two patterns as to what kind of material the pad holder 12 is formed and at which stage it is bent.

  (A) A first pattern in which the pad holder 12 (flat plate material) is molded with a thermoplastic resin that becomes soft and easy to bend by heating, and the bending grooves 14 are shallowed and bent at the manufacturing stage.

  (B) A second pattern in which the bending grooves 14 are deepened and bent at room temperature in order to improve the bendability.

  The first pattern (b) is bent (mainly bent) so as to substantially match the cross-sectional shape of the first-stage boom member 1 in the manufacturing stage, and the pad holder 12 is moved to the inner periphery of the first-stage boom member 1. This is suitable for the adjustment bending in which the degree of curvature is adjusted so as to match the actual cross-sectional shape of the boom material 1 as necessary at the assembling stage on the surface, and both the main bending and the adjusting bending have good bending work efficiency.

  On the other hand, the second pattern (b) is disadvantageous in terms of strength because the bending grooves 14 are deep, but it can be bent other than the thermoplastic resin and can be bent at the assembly stage.

  The pad holder 12 preferably has sufficient strength and hardness to support the load received via the pad 13, ease of bending (flexibility), and tenacity that does not break even when folded.

  Furthermore, it is desirable to use a synthetic resin material that is as cheap as possible even if the sliding performance is low, and a polyamide-based resin is preferable as satisfying the above conditions.

  The pad holder 12 is provided with folding auxiliary grooves 15 that open downward and extend in the boom length direction at locations corresponding to the folding grooves 14 on the lower surface side.

  In this way, by providing grooves (folding auxiliary grooves 15 that open downward) 15... On the lower surface side, the bending grooves 14 are especially avoided in order to avoid a decrease in strength compared to the case where the auxiliary grooves 15 are not provided. Even when shallower, the pad holder 12 can be easily bent and easily fitted to the inner peripheral surface of the first stage boom member 1.

  Further, on the upper surface of the pad holder 12, a plurality of recesses 16 are formed in the portion between the bending grooves 14. The recesses 16 are closed and open upward, and the pads 13 are detachably fitted into the recesses 16. It is.

  The pad holder 12 is fixed to the outer peripheral surface of the distal end portion of the first-stage boom member 1 by the holder fixing means in the boom circumferential direction and the length direction.

  As shown in FIGS. 1 and 4 to 6, the holder fixing means includes a front side fixing member 17 that is detachably attached to the distal end portion of the first stage boom member 1 in a state in which the pad holder 12 is restrained from the front side. In a state in which the pad holder 12 is constrained from the rear side at a plurality of locations in the boom circumferential direction, the rear side fixing member 18 attached to the inner peripheral surface of the outer boom material, and in a state in which the pad holder 12 is constrained from both sides in the boom circumferential direction. It consists of the circumferential direction fixing member 19 attached to the internal peripheral surface of an outer side boom material.

  The front-side fixing member 17 is formed in a semicircular curved band plate shape, and a plurality of front-side fixing members 17 are formed on the lower front surface of the flange 1 a provided at the front end of the first-stage boom member 1 in contact with the front surface of the pad holder 12. It is attached by a bolt 20 (see FIG. 6).

  1 exemplifies the case where the semicircular front fixing member 17 is formed by a plurality of divided pieces 17a..., The member 17 may be integrally formed in a series.

  The rear side fixing members 18 are formed in a square plate shape as shown in FIGS. 1 and 6, and are arranged at positions where they contact the rear surface of the pad holder 12 via the protective plate 21. It is attached by welding or the like in several directions.

  The protective plate 21 is for preventing damage to the rear surface of the holder due to direct contact between the rear side fixing member 18 and the pad holder 12, and is attached to the rear surface of the pad holder 12 with a bolt 22.

  The protective plate 21 may be provided for each rear fixing member 18 or across a plurality or all of the rear fixing members 18.

  As shown in FIG. 4, the circumferential direction fixing member 19 is formed in a plate shape thinner than the pad holder 12, and the first-stage boom material 1 is positioned at a position where the pad holder 12 can be sandwiched from both sides in the circumferential direction and fixed in the circumferential direction. It is attached to the inner peripheral surface by welding or the like.

  The pads 13 are formed in a rectangular flat plate shape using a synthetic resin material different from that of the pad holder 12, and the upper-stage side protrudes from the recesses 16 while being fitted in the recesses 16 of the pad holder 12. It touches the outer peripheral surface of the slide and exerts a slide support function.

  Here, the pads 13 are individually fixed in the boom circumferential direction and the length direction by the four circumferential walls in a state where the pads 13 are fitted in the recesses 16 of the pad holder 12.

  Then, the pad holder 12 is fixed in the boom circumferential direction and the length direction by the holder fixing means as described above, so that each pad 13... Is attached to the inner circumferential surface of the distal end portion of the first stage boom member 1 in the boom circumferential direction and length. The position is fixed in the vertical direction.

Since the pads 13 are sliding members for assisting the sliding of the second-stage boom material 2, compared with the pad holder 12 that merely holds the pads 13 ... Synthetic resin material (including wear resistance for maintaining
(I) a small coefficient of dynamic friction;
(Ii) the difference between the coefficient of static friction and the coefficient of dynamic friction is small;
(Iii) It is desirable to use a synthetic resin material that satisfies at least one condition of high wear resistance.

  Among these, when a synthetic resin material that satisfies the conditions (i) and (ii) is used, there is no so-called squeezing, in which the second-stage boom material 2 is intermittently moved at the beginning of boom expansion and contraction, and the start-up is smooth. Become.

  Incidentally, according to the inventors' experiment on the sliding performance of the pad 13, the static friction coefficient is about 0.15 when the surface pressure, which is the use environment of the pad in the crane boom, is 90 Kg / cm 2 to the limit value of 180 Kgf / cm 2. Those satisfying the condition that the dynamic friction coefficient is about 0.1 (the difference between the two friction coefficients is 0.05) are suitable for ensuring good sliding performance including the startability.

  As a specific material, an oil-containing synthetic resin excellent in lubricity, particularly an oil-containing polyamide-based resin and an oil-containing polyacetal-based resin are preferable.

  Further, since the pads 13 are merely fitted into the recesses 16 of the pad holder 12 and are detachable, it is desirable to press fit the recesses 16 so as not to easily fall off.

  However, this may make it difficult to extract the pad 13 during replacement due to damage or wear.

  Therefore, a pad extraction hole 23 is provided through the bottom surface of the recess 16 of the pad holder 12 in the holder thickness direction, and a thrust bar 24 (shown in FIG. 6) is inserted into the pad extraction hole 23 from the back side to provide a pad 13. It is comprised so that it can protrude easily upwards.

  The pad extraction holes 23 may be provided on both the front and rear sides of the bottom surface of the recess as shown, or may be provided only in the center portion.

  FIG. 4 shows the mounting state of the slide support member 11 on the inner peripheral surface of the first-stage boom member 1 by only the left and right half halves, but the opposite half is also mounted symmetrically.

  Moreover, in the same figure, the case where the two slide support members 11 and 11 are provided adjacent to each other in the boom circumferential direction in a state where the one end surfaces in the boom circumferential direction are in contact with each other is illustrated. The entire lower inner peripheral surface of the first stage boom member 1 may be covered with the support member 11.

  In addition, even if it uses together the slide support member 11 which concerns on embodiment, and the well-known slide support member (one or both of the well-known techniques 1 and 2) including the said well-known techniques 1 and 2 with the same boom material. Good.

  FIG. 4 illustrates a case where a known pad 25 is used on the side wall portion of the boom member 1.

Also, the assembly of the boom including the assembly of the slide support member 11 is
I. The rear side of the holder fixing means, the attachment of both circumferential fixing members 18, 19 to the first stage boom member 1,
II. Mounting of the pad holder 12,
III. Fitting of the pads 13 into the recesses 16 of the pad holder 12,
IV. Installation of the front fixing member 17;
V. This is done by inserting the second-stage boom member 2.

Here, since the bending groove 14... Is provided on the upper surface of the pad holder 12 and the bending auxiliary groove 15.
(A) When the pad holder 12 is bent in advance in the manufacturing stage and adjusted and bent in the assembly stage,
(B) The pad holder 12 can be easily bent in accordance with the inner peripheral surface of the first-stage boom member 1 in any of the cases where the pad holder 12 is bent from a flat plate shape to a curved shape and adjusted and bent at the assembly stage. It can be bent and securely fitted.

  Further, since the plurality of pads 13 are fitted into the recess 16 of the belt-like pad holder 12 and arranged in parallel in the boom circumferential direction, firstly, only the pad holder 12 is used as the first stage boom member 1 by the holder fixing means. The positions of all the pads 13 can be simultaneously fixed by fixing the positions in the boom circumferential direction and the length direction.

  For this reason, as compared with the known technique 1 (split pad), the assembly work of the pad is simplified.

  Secondly, since the pads 13 are fitted into the recesses 16 of the pad holder 12, the pads 13 are not likely to fall off due to the sliding contact resistance with the second-stage boom member 2.

  Third, unlike the prior art 2, since the pad thickness can be freely selected for each pad, when the gap between the boom members 1 and 2 differs in each part in the boom circumferential direction, Even when there is a gap variation due to a manufacturing error or the like, it is possible to fit all the pads 13 to the outer peripheral surface of the second-stage boom member 2 by selecting the pad 13 having a thickness corresponding to the gap.

  That is, it is possible to achieve both the workability of assembling the pad and the improvement of the pad performance of assisting the sliding of the second stage boom member 2.

Other Embodiments (1) Although it is desirable to provide the folding auxiliary grooves 15 of the pad holder 12, even when the pad holder 12 is not provided, as a basic effect of the folding grooves 14 as a basic effect, The fitting property with respect to the inner surface of the first-stage boom material can be enhanced.

  (2) The pad holder 12 and the pads 13 are desirably formed of different synthetic resin materials having characteristics suitable for each as in the above embodiment, but at least good sliding performance of the pads 13 can be ensured. Both may be formed of the same synthetic resin material.

  (3) It is desirable that the pads 13 are detachably fitted in the recess 16 of the pad holder 12, but if the entire pad holder is replaced, the pad 13 should be fitted in the recess 16 in order to strengthen the pad fixing force. It may be fixed by adhesion or the like.

1 First stage boom material (outside boom material)
2 Second stage boom material (inner boom material)
3 Third stage boom material 4 Fourth stage boom material 11 Slide support member 12 Pad holder constituting slide support member 13 Same pad 14 Bending groove 15 of pad holder Same as above, Folding auxiliary groove 16 Same as above, Concave portion 17 Constructing holder fixing means Front side fixing member 18 Same as above, Rear side fixing member 19 Same as above, circumferential direction fixing member 23 Pad extraction hole of pad holder

Claims (10)

  A boom slide support member used for a telescopic boom constructed by telescopically fitting a plurality of boom members whose bottom portions in a horizontal state of the boom are curved downwardly, and adjacent to each other. A belt-shaped pad holder that is attached to the inner peripheral surface of at least the lower part of the outer boom material among both boom materials over a certain range in the circumferential direction of the boom, and supports the boom material slidably in contact with the outer peripheral surface of the inner boom material The pad holder has a plurality of pads that open upward and extend in the boom length direction as means for assisting bending of the pad holder into a curved shape on the upper surface side facing the inner boom member. Bending grooves are provided at intervals in the circumferential direction of the boom, and a plurality of recesses are provided in the portion between the bending grooves and the four circumferences are closed and open upward. Head is sliding support member for a boom, characterized in that mounted in a state fitted into and is fixed in position the boom circumferential direction and length direction of the recess.   2. A slide support member for a boom according to claim 1, wherein a bending auxiliary groove that opens downward and extends in the boom length direction is provided at a position corresponding to each of the bending grooves on the lower surface side of the pad holder. .   3. The boom support member according to claim 1, wherein the pad holder and the pad are formed of different synthetic resin materials. Compared to the pad holder, the pad
(I) a small coefficient of dynamic friction;
(Ii) the difference between the coefficient of static friction and the coefficient of dynamic friction is small;
The slide support member for a boom according to claim 3, wherein at least one condition of (iii) high wear resistance is satisfied. Claim 3 or 4 SL placing the sliding support member for a boom, characterized in that the pad is formed by oil-impregnated type synthetic resin material. The pad holder, with a thermoplastic resin material, in advance, any one of the preceding claims, characterized in that the heated molded into a curved shape corresponding to the inner peripheral surface of the outer boom member is attached target The slide support member for booms described in 1. The boom slide support member according to any one of claims 1 to 6, wherein each of the pads is detachably fitted into a recess of the pad holder . Pas Tsu the bottom surface of the recess in the de holder, sliding support member for a boom according to claim 7 Symbol mounting pad extraction hole penetrating the pad holder thickness direction, characterized in that provided et the. In a telescopic boom constructed by fitting a plurality of boom members whose bottom portions in the horizontal state of the boom are curved downwardly into a telescope shape, at least of the outer boom members among the adjacent inner and outer boom members. The slide support member according to any one of claims 1 to 8 and a holder fixing means for fixing the pad holder of the slide support member in the boom circumferential direction and the boom length direction are provided in the lower part. Boom featuring. As the holder fixing means, a front side fixing member that is detachably attached to the distal end portion of the outer boom material in a state in which the pad holder is restrained from the front side, and a state in which the pad holder is restrained from the rear side at a plurality of locations in the boom circumferential direction. A rear side fixing member attached to the inner peripheral surface of the outer boom material, and a circumferential direction fixing member attached to the inner peripheral surface of the outer boom material in a state of restraining the pad holder from both sides in the boom circumferential direction. The boom according to claim 9 .

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