JP2010208575A - Caster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a caster capable of sufficiently damping a sudden impact and also damping an impact even when a load weight is suddenly reduced by reducing the spring constant of a damping member which absorbs the impact transmitted from a wheel or a body thereto through a link member while a vehicle travels or when a load weight changes. <P>SOLUTION: The damping member comprising a cylindrical coiled spring and a cylindrical viscoelastic resin is installed on a bolt in series along the longitudinal direction of a body case elongated in the traveling direction. The wheel is supported at the long leg side end of a pair of L-links, the base is rotatably attached to the sidewall of the body case and associated with the rear end of the damping member through a push block at the short leg side end, and the movements of the short leg side end and the push block due to the upward movement of the wheel are absorbed by the damping member. An auxiliary coiled spring is disposed on the rear sides of the damping member and the push block to absorb the rearward movements of the short leg side end and the push block due to the downward movement of the wheel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  This invention is attached to a cart for moving and conveying materials, products, etc. in a factory, for example, and not only with respect to a normal load resistance of 80 to 100 kg, but also small impact received from unevenness of the floor surface during movement. The present invention relates to a caster including a shock absorbing member that absorbs with high shock resistance without amplitude vibration.

  FIG. 5 shows an example of a conventional caster with a buffer member. A fork for pivotally suspending a wheel 1 is separated into an upper fork 2 and a lower fork 3. The wheel shaft 5 is inserted into the shaft support hole, and the connecting shaft 6 is inserted into the shaft support hole on the short leg side base and the shaft support hole on the tip of the upper fork 2 corresponding thereto, so that both forks can be rotated. Then, the conical coil spring 4 is mounted in a compressed state between the long leg side tip of the L-shaped lower fork 3 and the inner wall of the main body portion of the upper fork 2 covering the L-shaped lower fork 3. The load applied to the connecting shaft 6 from the head of the upper fork 2 pushes down the short leg side base of the lower fork 3, so that the long leg end of the lower fork 3 rotates in the direction pushing the small diameter side end of the conical coil spring 4. It moves to compress the conical coil spring 4 and buffer the load. Similarly, the unevenness of the floor surface moves the wheel shaft 5 up and down, the long leg side of the lower fork 3 rotates about the connecting shaft 6 and compresses or extends the conical coil spring 4 to buffer the impact due to the unevenness. (See Patent Document 1)

  The conical coil spring used in the caster shown in FIG. 5 has a non-linear spring constant, and the displacement of the spring increases as the impact increases. Therefore, it is possible to effectively buffer a strong impact in a place with a large step, It is said that the spring constant should be increased rapidly for use in a place with large unevenness. However, in the configuration shown in FIG. 5, the distance between the connecting shaft 6 and the long leg side tip is larger than the distance between the wheel shaft 5 on the short leg side of the L-shaped lower fork 3 and the connecting shaft 6. large. For this reason, when a sudden load is applied to the connecting shaft 6, the rotation of the front end on the long axis centering on the wheel shaft 5 rapidly pushes the small diameter end of the conical coil spring 4 at the doubled speed and stroke. For this reason, if the spring constant of the conical coil spring 4 is not adapted to this situation, the conical coil spring is exposed to the risk of breakage. Conversely, if the load is momentarily reduced during use of the caster, the rotational speed and stroke of the long leg side end of the lower fork 3 that extends the conical coil spring 4 are also doubled. Collisions and damages between the constituent members of the upper and lower forks 2 and 3 are inevitable.

Japanese Patent No. 3799554

  A conventional caster with a cylindrical coil spring that functions as a buffer against shocks caused by load or unevenness on the floor surface has a relatively large spring constant. If a sudden impact is exceeded, not only the spring itself but also the spring support member may be damaged. On the other hand, when using a conical coil spring whose spring constant changes in response to an impact, in addition to the risk of breakage due to an abrupt impact, avoid collisions between spring support members in the event of an instantaneous load reduction. I can't. In either case, the vibration transmissibility is large, and the buffer function in the case of sudden impact or sudden decrease in load load is not sufficiently fulfilled.

  The present invention has been proposed with these points as problems. Therefore, the vibration transmission rate or the spring constant as a whole is small, and a sudden shock is sufficiently buffered. It is an object of the present invention to provide a caster having a buffering function that can be achieved.

According to the present invention, the caster according to claim 1 has a pedestal in the upper part and a link member that holds both ends rotatably in the lower part, and a buffer that absorbs the rotation of one end of the link member in the intermediate part. It comprises a main body having a member and a wheel rotatably attached to the other end of the link member, and the buffer member is composed of a coil spring and a viscoelastic resin arranged in series in the rotation direction of one end of the link member. To do.
The caster according to claim 2 is the caster according to claim 1, wherein the main body includes a pair of opposing legs each having a shaft supporting hole at the lower portion thereof, and a main shaft carrying a pedestal attached to the upper portion through a bearing. The link member is a cover case provided with a cushioning material extending along the traveling direction in the middle portion that is long in the traveling direction, and the link member rotatably supports the wheel via the axle at the long leg side tip. A pair of L-shaped members that are linked to the rear end of the cushioning material at the front end via a linkage member and that are pivotally attached to the cover case with respect to the pivot shaft that is inserted into the shaft support hole of the opposite leg of the cover case at the intermediate base. It consists of a link, and the buffer member is inserted through the bolt nut attached between the opposing walls in the longitudinal direction of the middle part of the cover case, and the bolt nut bolt It consists of a cylindrical coil and viscoelastic resin assembly and a pushing piece with a bolt inserted through the rear end of this assembly, and the cooperation member extends in the direction in which the cushioning material extends to the opposing wall in the middle of the cover case A first long hole provided along the second long hole, a second long hole provided so as to extend from the tip of the short side of the L-shaped link toward the rotating shaft, and a short length of the L-shaped link through these long holes. It consists of a shoulder screw that pivotally connects the leg side tip to both ends of the push piece, and the upward movement of the axle is the movement of the short leg side end of the L-shaped link and the push piece in the caster traveling direction with the pivot shaft as a fulcrum. It is converted, and this movement is absorbed by the assembly of the coil spring and the viscoelastic resin.
The caster according to claim 3 is the caster according to claim 2, wherein the buffer member further includes an auxiliary coil spring through which a bolt is inserted on the rear side of the push piece, and the tip of the short leg side of the L-shaped link by the downward movement of the axle. The movement in the direction opposite to the caster traveling direction is absorbed by the auxiliary coil spring.

  According to the present invention, as a cushioning member between the pedestal and the wheel constituting the caster, it absorbs the movement in the caster traveling direction at one end of the link member when the load is increased or the wheel is moved upward while the caster is traveling. Thus, a combination assembly of a cylindrical coil spring and a cylindrical viscoelastic resin arranged in series coaxially in the caster traveling direction is used. Since the coil spring absorbs vibration or shock by compressive deformation and the viscoelastic resin absorbs both compression and tensile deformation, the buffer member used in the present invention has a small spring constant as a whole and a vibration transmissibility. Therefore, the vibration from the wheel to the load such as a cart using the caster is remarkably absorbed, and a sudden impact is also effectively absorbed to prevent the coil spring from being damaged.

  The caster according to the present invention is further provided on the rear side of the push piece so as to absorb the movement in the direction opposite to the caster traveling direction of one end of the link member accompanying the downward movement of the wheel when the load is suddenly removed. Auxiliary coil springs are mounted in series with the coil spring and viscoelastic resin assembly, so that the impact caused by the recoil when the load is suddenly removed can be reduced, and the coil spring and viscoelastic resin assembly can be stably held under no load. Make it possible.

FIG. 1 is a top view showing an internal buffer member by cutting a part of a base of a caster and a part of an upper wall of a cover case according to an embodiment of the present invention. FIG. 2 is a side view showing a cushioning member by cutting a part of the cover case side wall of the caster of FIG. FIG. 3 is a front view of the caster of FIG. FIG. 4 shows the deflection of a caster under a constant load when a combination of a coil spring and a viscoelastic resin of a buffer member used in the present invention is used as a viscoelastic resin using three types of polyurethane resins having different Shore hardnesses. The figure shown in comparison with the case where it is only. FIG. 5 is a side view showing the structure of a conventional caster.

  Hereinafter, the structure of the caster of the embodiment according to the present invention will be described with reference to FIGS.

  1 to 3, the caster of the embodiment according to the present invention is roughly composed of an L-shaped link 13 having a pedestal 24 in the upper part and pivoting the base part with both long and short leg ends pivotable in the lower part. A main body formed of a cover case 19 having a link member, and a buffer member made up of a coil spring 16 and a viscoelastic resin 17 that absorbs rotation of one end on the short leg side of the L-shaped link 13 in the middle portion; The wheel 11 is rotatably supported at the other end on the long leg side of the link member extending obliquely downward from the lower end. The upward movement of the wheel 11 and the axle 12 due to the load and the convex portion of the floor surface encountered during the progress of the caster travels on the short leg side end of the L-shaped link 13 with the pivot shaft 14 of the L-shaped link 13 as a fulcrum. It is converted into movement in the direction and is absorbed by the buffer member made up of the coil spring 16 and the viscoelastic resin 17 arranged in series along the traveling direction.

  The cover case 19 forming the main body is formed in a box shape having an opening on the lower side and extending in the direction of the caster with a width slightly larger than the width of the wheel 11, and a pair of opposing ends extending substantially at the center of the long side wall. Legs are formed and a shaft support hole is provided near the tip. A main shaft 25 with a pedestal 24 attached is supported on the upper surface of the cover case 19 via a bearing, and the short leg side of the pair of L-shaped links 13 is brought into contact with the outer side of the lower opposed leg so that the L-shaped link 13 The rotation shaft 14 of the L-shaped link 13 is inserted into the shaft support hole of the base portion and the shaft support hole of the opposite leg of the cover case 19, and the pair of L-shaped links 13 are freely rotatable about the rotation shaft 14. Install to. The wheel 11 is sandwiched between a pair of long leg-side tips of the L-shaped link 13 extending obliquely downward on the rear side from the lower part of the cover case 19, and the axle 12 held by the ball bearing is inserted into the shaft support hole at the long leg-side tip. Then, the wheel 11 is held rotatably and can be moved up and down with the rotation of the L-shaped link 13.

  Two bolts 20 are inserted between the opposite side walls of the box-like portion of the cover case 19 in parallel with each other along the caster traveling direction and fixed with nuts 21. A thick plate-like push piece 15 is inserted across the cylindrical coil spring 16, the cylindrical viscoelastic resin 17, and the two bolts 20. On both end surfaces of the push piece 15 are a first long hole 23 a provided in parallel with the bolt 20 on both side walls on the long side of the cover case 19, and a short leg on the short leg side tip of the pair of L-shaped links 13. A pair of shoulder screws 22 are screwed through a second elongated hole 23b provided along the length direction. Accordingly, the upward movement of the wheel 11 and the axle 12 leads to rotation of the short leg side tip and the shoulder screw 22 in the caster traveling direction with the rotation shaft 14 of the L-shaped link 13 as a fulcrum. The first and second elongated holes are slid to move the push piece 15 in the advancing direction of the caster. This movement is absorbed by the coil spring 16 and the viscoelastic resin 17 and is excellent particularly against a sudden movement shock. Demonstrate buffer capacity.

  Preferably, the buffer member according to the present invention further includes a pair of auxiliary coil springs 18 on the rear side of the push piece 15, that is, on the side opposite to the caster traveling direction, and the bolts 20 are respectively inserted therethrough. These auxiliary coil springs 18 are provided at the rear end of the short leg of the L-shaped link 13 or the back of the push piece 15 that is generated due to the downward movement of the wheel 11 or the axle 12 when the caster encounters a recess in the floor surface. Although it absorbs directional movement, it has excellent buffering capacity especially against sudden movement and its impact.

  The shock-absorbing member of the present invention comprising a coil spring and viscoelastic resin assembly exhibits a combined effect due to absorption of vibration due to compression deformation of the coil spring and absorption of vibration due to compression deformation and tensile deformation of the viscoelastic resin. The spring constant becomes small, and even if it receives strong vibration, there is no continuous generation of small amplitude vibration. Furthermore, the deformation of the viscoelastic resin against momentary compression of the coil spring prevents the coil spring from being damaged.

  In practice, for example, a cylindrical polyurethane having a length of 35 mm as a coil spring and an outer diameter of 14 mm and a spring constant of 7.0 kg / mm, and a cylindrical polyurethane having a length of 15 mm, an outer diameter of 14 mm and an inner diameter of 7 mm as a viscoelastic resin. Three groups of casters are prepared by combining three types of polyurethane resins with a Shore hardness of A95, A90, and A70, respectively, and the above coil springs. The casters in each group are 600 mm long, 450 mm wide, and 20 mm thick aluminum. Caster deflection was measured when a load of 150 kg was placed on each of the four corners of the plate. The measured values are shown in FIG. 4 in comparison with the measured values obtained by a caster (indicated as “spring only”) in which an iron pipe having the same shape is combined with a coil spring instead of the cylindrical polyurethane resin. As can be seen from the figure, the smaller the Shore hardness of the polyurethane resin used as the viscoelastic resin, the greater the amount of bending of the caster, and the greater the degree of synthesis of the buffer spring and the buffering properties of the viscoelastic resin. This also has the effect of speeding up the vibration damping response by preventing the vibration or impact transmitted by the coil spring through the L-shaped link and at the same time suppressing the free vibration of the coil spring by the viscoelastic resin.

11 Wheel 12 Axle 13 L-shaped link 14 Rotating shaft 15 Pushing piece 16 Coil spring 17 Viscoelastic resin 18 Auxiliary coil spring 20 Bolt 21 Nut 22 Shoulder screw 23a First long hole 23b Second long hole 24 Base 25 Main shaft

Claims (3)

  A main body having a pedestal at the upper part and a link member holding both ends rotatably at the lower part and a buffer member for absorbing the rotation of one end of the link member at the middle part, and rotating at the other end of the link member A caster comprising a freely attached wheel, and a buffer member comprising a coil spring and a viscoelastic resin arranged in series in a rotation direction of one end of the link member. The main body includes a pair of opposing legs each having a shaft supporting hole at the lower portion thereof, and supports the main shaft with a pedestal attached at the upper portion, and has a longitudinal direction in the moving direction of the caster along the traveling direction. A cover case with extended cushioning material,
The link member rotatably supports the wheel via the axle at the front end of the long leg, cooperates with the rear end of the cushioning material via the cooperation member at the front end of the short leg, and at the intermediate base, the shaft of the opposite leg of the cover case It consists of a pair of L-shaped links that are pivotably attached to the cover case with respect to the pivot shaft inserted through the support hole.
The buffer member includes a bolt nut attached between opposing walls in the longitudinal direction of the intermediate portion of the cover case, a cylindrical coil and viscoelastic resin assembly through which the bolt of the bolt nut is inserted, and a rear end of the assembly. It consists of a push piece through which a bolt is inserted,
The linking member is provided in the opposite wall body in the middle part of the cover case so as to extend from the short leg side tip of the L-shaped link toward the rotating shaft in the extending direction of the cushioning material. The second elongated hole and a shoulder screw that pivotally connects the tip of the short leg side of the L-shaped link to both ends of the push piece through these elongated holes, and the upward movement of the axle is a fulcrum. 2. The caster according to claim 1, wherein the caster is converted into a movement of the short leg side end of the L-shaped link and the push piece in the caster traveling direction, and the movement is absorbed by a coil spring and a viscoelastic resin assembly.   The buffer member further includes an auxiliary coil spring through which a bolt is inserted on the rear side of the push piece, and the auxiliary coil spring absorbs the movement in the direction opposite to the caster traveling direction of the short leg side end of the L-shaped link due to the downward movement of the axle. The caster according to claim 2, wherein:

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