TW201742721A - Linear extension and retraction mechanism - Google Patents

Abstract

In order to improve the durability of a feeding mechanism in a direct-acting extension/retraction mechanism, this direct-acting extension/retraction mechanism is equipped with: multiple flat-plate-shaped first segments (53) coupled to each other so as to be capable of bending at the front and back end surfaces; multiple groove-shaped second segments (54) coupled to each other so as to be capable of bending at the front and back end surfaces of a base part; a coupling segment (55) that couples the leading ends of the first and second segments; and a feeding mechanism part (26) equipped with multiple rollers (59, 60) for rigidly joining the first and second segments and supporting the segments so as to be capable of moving back and forth. The first and second segments are joined to each other by the rollers and stiffen into a straight line when the segments are fed forward, and together with the coupling part, form a columnar arm part, whereas the first and second segments are separated from each other at the rear of the rollers when the segments are drawn back, and return to a bent state. The rollers are formed from the same material as the first and second segments.

Description

Direct motion telescopic mechanism

Embodiments of the present invention relate to a linear motion expansion mechanism.

Since the prior art, the multi-joint robot arm mechanism has been used in various fields such as industrial robots. The inventors and the like have developed a linear motion expansion mechanism that can be applied to such a multi-joint mechanical arm mechanism (Patent Document 1). The linear motion retracting mechanism is used for the multi-joint robot arm mechanism, and since the elbow joint portion is not required and the critical point can be easily eliminated, it is a very advantageous configuration.

The linear motion retracting mechanism includes: a plurality of links (first link) made of a metal having a flat plate shape that are bendably coupled; and a plurality of links made of metal having a groove shape that are bendably coupled to the bottom plate (No. Two chain links). The first and second links are coupled at the front end, and when the front side is sent out, the first and second links are coincident to ensure a hard straight state. Thereby, a columnar arm portion having a certain rigidity is formed. When pulled back toward the rear, the first and second links are separated and restored to a bendable state, and are accommodated inside the pillar. The sending mechanism is equipped with a plurality of rollers on the four sides of the frame of the corner cylinder shape, and the first and second links are clamped from the four directions to move forward and backward, and The arms are supported up and down and left and right.

The wrist is equipped at the front end of the arm, and the wrist is equipped with an end effector, and the end effector holds the workpiece. In order to support the weight of the material, the workpiece is transferred to the front and rear, and the upper and lower sides, and the arm portion is required to be very firmly held by the roller. Therefore, the outer peripheral surface (rolling surface) of the roller is easily worn. When the outer surface of the roller is worn, it is difficult for the arm portion to smoothly perform the linear expansion and contraction operation, and as a result, the durability of the delivery mechanism is lowered.

However, if only the steel is composed of steel from the viewpoint of improving the durability of the roller, the first and second links are damaged by the roller, and the durability of the feeding mechanism is still lowered. The roller is cheaper than the first and second links, so the replacement object should not be the first and second links but should be rollers.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5435679

The object of the present invention is to achieve an improvement in the durability of the feeding mechanism of the linear motion stretching mechanism.

The linear motion expansion/contraction mechanism of the present embodiment includes a plurality of first link segments having a flat plate shape, and the first link segments are bendably coupled to each other at the front and rear end faces; and the plurality of second link segments having a groove shape are mutually front and rear end faces of the bottom portion Curved ground a joint that joins the foremost ends of the first and second links; and a delivery mechanism that equips the plurality of rollers in order to securely engage the first and second links and move back and forth freely . The first and second links are straight and rigid when they are fed forward to each other by rollers, and form a columnar arm together with the joint portion, and are separated from each other after being pulled back toward the rear. And restored to a bent state. The roller system is constructed of the same material as the first and second links.

5‧‧‧arm

26‧‧‧Corner frame

53‧‧‧First link

54‧‧‧second chain link

59‧‧‧Up and down rolls

60‧‧‧ left and right rolls

551, 552, 553, 554‧‧‧ slot

Fig. 1 is a view showing the appearance of a mechanical arm mechanism equipped with a linear motion expansion joint according to a first embodiment.

Fig. 2 is a view showing the configuration of the mechanical arm mechanism of Fig. 1 by the symbol representation.

Fig. 3 is a side view showing the internal structure of the mechanical arm mechanism of Fig. 1.

Fig. 4 is a view showing the configuration of the mechanical arm mechanism of Fig. 1 by the symbol representation.

Fig. 5 is a perspective view showing the delivery mechanism of Fig. 3.

Fig. 6 is a view showing a plurality of rollers provided in the delivery mechanism of Fig. 3 together with the first and second link rows.

Hereinafter, the linear motion expansion mechanism of the first, second, and third embodiments will be described with reference to the drawings. Furthermore, the linear motion expansion mechanism of each embodiment can be used as a separate mechanism (joint). In the following description In the middle, a robot arm mechanism in which one of the plurality of joint portions is constituted by the linear motion expansion mechanism of each embodiment will be described as an example. As the mechanical arm mechanism, a robot arm mechanism having a polar coordinate type of a linear motion expansion mechanism will be described here, but other types of mechanical arm mechanisms may be used. In the following description, components having substantially the same functions and configurations are denoted by the same reference numerals, and the description will be repeated only when necessary.

Fig. 1 is a view showing the appearance of a mechanical arm mechanism equipped with the linear motion retracting mechanism of the first embodiment. Figure 2 is a side elevational view of the robotic arm mechanism of Figure 1. Fig. 3 is a side view showing the internal structure of the mechanical arm mechanism of Fig. 1.

The arm mechanism includes a base 1, a post portion 2, a shoulder portion 4, an arm portion 5, and a wrist portion 6. The pillar portion 2, the shoulder portion 4, the arm portion 5, and the wrist portion 6 are sequentially disposed from the susceptor 1. A plurality of joint portions J1, J2, J3, J4, J5, and J6 are sequentially disposed from the susceptor 1. The pillar portion 2 forming the cylindrical body on the susceptor 1 is typically provided vertically. The pillar portion 2 houses the first joint portion J1 as a turning joint portion. The first joint portion J1 has a rotation axis RA1. The rotating shaft RA1 is parallel to the vertical direction. The pillar portion 2 has a lower frame 21 and an upper frame 22. One end of the lower frame 21 is connected to the fixed portion of the first joint portion J1. The other end of the lower frame 21 is connected to the base 1. The lower frame 21 is covered by a cylindrical casing 31. The upper frame 22 is connected to the rotating portion of the first joint portion J1, and pivots about the rotation axis RA1. The upper frame 22 is covered by a cylindrical casing 32. As the first joint portion J1 rotates, the upper frame 22 rotates relative to the lower frame 21, whereby the arm portion 5 is horizontally rotated. The first and second link rows 51 and 52 of the third joint portion J3, which will be described later as a linear motion expansion mechanism, are hollowly accommodated inside the pillar portion 2 forming the cylindrical body.

A shoulder portion 4 that houses the second joint portion J2 as the undulating rotary joint portion is provided at an upper portion of the pillar portion 2. The second joint portion J2 is a rotating joint. The rotation axis RA2 of the second joint portion J2 is perpendicular to the rotation axis RA1. The shoulder portion 4 has one side frame 23 as one of the fixing portions (support portions) of the second joint portion J2. The pair of side frames 23 are coupled to the upper frame 22. The pair of side frames 23 are covered by a saddle-shaped outer cover 33. A cylindrical body 24 serving as a rotating portion of the second joint portion J2 that also serves as a motor housing is supported by the pair of side frames 23. A delivery mechanism 25 is attached to the circumferential surface of the cylindrical body 24. The drive gear 56, the guide roller 57, and the roller unit 58 are supported by the frame 26 of the delivery mechanism 25. As the shaft of the cylindrical body 24 rotates, the delivery mechanism 25 rotates to support the arm portion 5 supported by the delivery mechanism 25 up and down. The delivery mechanism 25 is covered by a cylindrical outer cover 34. The gap between the saddle cover 33 and the cylindrical outer cover 34 is covered by a U-shaped bellows outer cover 14 having a U-shaped cross section. The U-shaped corona cover 14 is stretched and contracted following the undulating movement of the second joint portion J2.

The third joint portion J3 is provided by a linear motion stretching mechanism. The linear motion expansion mechanism has a newly developed structure by the inventors and the like, and is clearly distinguished from the so-called previous direct motion joint from the viewpoint of the movable range. The arm portion 5 of the third joint portion J3 is freely bendable, but the bending is restricted when the feed mechanism 25 from the root portion of the arm portion 5 is fed forward along the center axis (the telescopic center axis RA3) to ensure linear rigidity. When the arm portion 5 is pulled back toward the rear, the bending is resumed. The arm portion 5 has a first chain link row 51 and a second chain link row 52. The first link row 51 includes a plurality of first links 53 that are freely coupled. The first link 53 is formed in a substantially flat shape. The first link 53 is flexibly coupled by a hinge portion (hinge portion) of the end portion. The second chain link row 52 includes a plurality of second links 54. The second link 54 is configured as a cross section " a groove-shaped body of a glyph or a tubular shape of a "mouth" shape. The second link 54 is flexibly connected by a hinge portion of the end portion of the bottom plate. The curvature of the second chain link 52 is tied to the second link. The positions at which the end faces of the side plates of 54 abut each other are restricted. At this position, the second link rows 52 are linearly arranged. The first link 53 and the second link row 52 of the foremost end of the first link row 51 The foremost second link 54 is connected by a joint link 55. For example, the joint link 55 has a shape in which the first link 53 and the second link 54 are combined.

The first and second chain link rows 51, 52 are pressed and joined to each other when passing through the roller unit 58. The first and second link rows 51 and 52 are linearly rigid by joining, and constitute a columnar arm portion 5. Immediately after the roller unit 58, the drive gear 56 is disposed together with the guide roller 57. The drive gear 56 is connected to a motor unit (not shown). The motor unit generates power for rotating the drive gear 56. A linear gear 539 is formed along the connecting direction at the center of the inner surface of the first link 53, that is, the surface on the side joined to the second link 54. When the plurality of first links 53 are linearly aligned, the adjacent linear gears 539 are linearly connected to form a long linear gear. The drive gear 56 meshes with the linear gear 539 of the first link 53 which is pressed by the guide roller 57. The linearly connected linear gear 539 is combined with the drive gear 56 to constitute a rack and pinion mechanism. When the drive gear 56 rotates in the forward direction, the first and second link rows 51, 52 are fed forward from the roller unit 58 toward the front. When the drive gear 56 rotates in the reverse direction, the first and second link rows 51, 52 are pulled back toward the rear of the roller unit 58. The first and second link rows 51, 52 that are pulled back are separated from each other between the roller unit 58 and the drive gear 56. First after separation, The second link rows 51, 52 are respectively restored to a bendable state. The first and second link rows 51 and 52 that have been restored to the bendable state are all bent in the same direction (inner side), and are vertically stored inside the pillar portion 2. At this time, the first link row 51 is accommodated in a substantially aligned state substantially in parallel with the second link row 52.

A wrist portion 6 is attached to the front end of the arm portion 5. The wrist 6 is equipped with fourth to sixth joint portions J4 to J6. The fourth to sixth joint portions J4 to J6 each have orthogonal three-axis rotation axes RA4 to RA6. The fourth joint portion J4 has a rotary joint of a fourth rotating shaft RA4 that substantially coincides with the telescopic central axis RA3. The end effector swings and rotates by the rotation of the fourth joint portion J4. The fifth joint portion J5 has a rotary joint of a fifth rotating shaft RA5 disposed perpendicular to the fourth rotating shaft RA4. The end effector tilts back and forth by the rotation of the fifth joint portion J5. The sixth joint portion J6 has a rotation joint of a sixth rotation shaft RA6 that is disposed perpendicular to the fourth rotation axis RA4 and the fifth rotation axis RA5. The end effector performs shaft rotation by the rotation of the sixth joint portion J6.

The end effector (end effector) is attached to the adapter 7 provided at the lower portion of the rotating portion of the sixth joint portion J6 of the wrist portion 6. The end effector has a function of allowing the robot to directly act on the work object (workpiece), and for example, there are a retaining portion, a vacuum suction portion, a nut fastener, a welding gun, a spray gun, and the like, depending on the task. The end effector is moved to an arbitrary position by the first, second, and third joint portions J1, J2, and J3, and is disposed in any posture by the fourth, fifth, and sixth joint portions J4, J5, and J6. . In particular, the length of the telescopic distance of the arm portion 5 of the third joint portion J3 can be The end effector reaches a wide range of objects from the proximity of the base 1 to the remote location. The third joint portion J3 is characterized in that the linear telescopic movement realized by the linear motion expansion mechanism constituting the third joint portion J3 and the length of the telescopic distance thereof are different from the previous direct motion joint.

Fig. 4 is a view showing the configuration of the mechanical arm mechanism by the symbol representation. In the arm mechanism, three positional degrees of freedom are realized by the first joint portion J1, the second joint portion J2, and the third joint portion J3 which constitute the three axes of the root. Further, three posture degrees of freedom are realized by the fourth joint portion J4, the fifth joint portion J5, and the sixth joint portion J6 which constitute the three axes of the wrist. As shown in FIG. 4, the rotation axis RA1 of the first joint portion J1 is provided in the vertical direction. The rotation axis RA2 of the second joint portion J2 is provided in the horizontal direction. The second joint portion J2 is offset from the first joint portion J1 in two directions of the rotation axis RA1 and the axis orthogonal to the rotation axis RA1. The rotation axis RA2 of the second joint portion J2 does not intersect the rotation axis RA1 of the first joint portion J1. The movement axis RA3 of the third joint portion J3 is oriented perpendicular to the rotation axis RA2. The third joint portion J3 is offset from the second joint portion J2 in two directions of the rotation axis RA1 and the axis orthogonal to the rotation axis RA1. The rotation axis RA3 of the third joint portion J3 does not intersect the rotation axis RA2 of the second joint portion J2. One of the three rotation axes of the plurality of joint portions J1 - J6 is replaced by the linear motion joint portion J3, and the second joint portion J2 is displaced in two directions with respect to the first joint portion J1, and The third joint portion J3 is displaced in two directions with respect to the second joint portion J2, whereby the mechanical arm mechanism of the robot apparatus of the present embodiment structurally eliminates the critical point posture.

Fig. 5 is a view showing the configuration of the delivery mechanism 25 of Fig. 3. Figure 6 is A perspective view of the roller of Fig. 5 together with the chain links 51, 52 is shown. The delivery mechanism 25 is provided with a roller unit 58. The roller unit 58 constitutes one of the main structures of the linear motion expansion mechanism (third joint portion J3) together with the first and second link rows 51 and 52. The roller unit 58 is equipped with a plurality of upper and lower rollers 59 and a plurality of left and right rollers 60. The rollers 59, 60 include a cylindrical rolling body, a bearing, and a shaft.

The upper and lower rollers 59 are supported by a pair of plate-shaped frames 58 such that their rotation axes are orthogonal to the movement axis RA3 of the arm portion 5 and parallel to the rotation axis RA2. There are four upper and lower rollers 59, for example, two of which are disposed on the upper side of the moving shaft RA3, and the remaining two are disposed on the lower side. The two rollers 59 on the upper side and the lower side are arranged in a row along the movement axis RA3 by a certain distance in such a manner that the rotation axes are parallel to each other. The upper two rolls 59 and the lower two rolls 59 are separated by a distance equal to the total thickness of the joined first and second links 53, 54. Here, the total thickness of the first and second links 53, 54 is substantially equivalent to the distance from the lowermost portion of the arm portion 5 to the uppermost portion of the arm portion 5. Thereby, the upper and lower rollers 59 can join the first and second links 53, 54 and can be firmly joined from the upper and lower sides and can be supported by being movable back and forth.

The left and right rollers 60 have a rotation axis orthogonal to the movement axis RA3 and the rotation axis RA2. For example, there are two left and right rollers 60, one of which is disposed on the left side of the moving shaft RA3, and the other one is disposed on the right side. The left side roller 60 and the right side roller 60 are spaced apart by a distance equivalent to the width of the first and second links 53, 54. Here, the widths of the first and second links 53, 54 are substantially equivalent to the outermost distance from the outermost side to the right side of the left side of the arm portion 5. Thereby, the right and left rollers 60 securely join the first and second links 53, 54 from the left and right sides. It is free to move forward and backward to support.

The rollers 59 and 60 are required to support the arm portion 5, the wrist portion 6 at the front end of the arm portion 5, and the total weight of the end effector of the adapter 7 provided on the wrist portion 6 to achieve smooth movement before and after the movement. The arm portion 5 is firmly held up, down, left, and right. Since the arm portion 5 is moved back and forth in a state in which the arm portion 5 is firmly clamped from the upper, lower, left, and right sides, the outer peripheral surface (rolling surface) of the rollers 59 and 60 is easily worn. The rollers 59 and 60 in the worn state hinder the smooth expansion and contraction of the arm portion 5, and the accuracy of moving the end effector to the target position is lowered. On the other hand, in order to improve the durability of the rolls 59, 60, the rolling elements of the rolls 59, 60 are made of a material having a higher hardness than the first and second links 53, 54, and the rolls 59, 60 are used. The rolling elements break the surface of the first and second links 53, 54. The first and second links 53, 54 are more expensive than the rollers 59, 60 and have many maintenance steps. Therefore, the material should be selected such that the breaking speed of the first and second links 53, 54 is slower than the rolls 59, 60.

In the present embodiment, 1) the durability of the rolls 59, 60 is improved, 2) the durability of the first and second links 53, 54 is improved, and in addition, 3) is simultaneously suppressed to the first and second rolls 59, 60. From the viewpoint of the aggressiveness of the links 53, 54 , the materials of the rollers 59, 60 and the first and second links 53, 54 are selected, and the rollers 59, 60 and the first and second links 53, 54 are selected. Whether or not the surface treatment is performed, the types of surface treatment of the respective rolls 59, 60 and the first and second links 53, 54 are selected, and the surfaces of the rolls 59, 60 and the first and second links 53, 54 are selected to be lubricated. The formation of the film layer selects the type of the lubricating film layer on the surfaces of the rolls 59, 60 and the first and second links 53, 54 respectively.

In addition, the term "surface treatment" as used herein refers to the treatment of forming a lubricating coating layer by applying a lubricant to the surface, and also refers to electroplating, electroless plating, nitriding, spraying, anodizing, ion implantation, and CVD. , high-hardness surface treatment for improving wear resistance, such as ion implantation and heat treatment. The anodic oxidation is, for example, aluminum, which is a surface treatment in which surface modification of an oxide film (aluminum oxide) is formed on the surface by electrolytic treatment of the anode.

The lubricating film layer forming treatment is performed by dispersing one or a plurality of solid lubricants such as molybdenum disulfide, graphite, fluororesin (tetrafluoroethylene, etc.), tungsten disulfide, and metal oxide in various organic resins to form a coating material. The drying treatment can be formed on the surface of the surface treated object. Typically, it is formed using a fluorine-based dry film lubricant. HANARL (registered trademark) manufactured by Kanto Chemical Co., Ltd. is preferably used as the fluorine-based dry film lubricant. HANARL contains a volatile solvent of 80 to 90 (by weight) as a main component and contains polytetrafluoroethylene (PTFE) as a fluorine-based resin. A fluorine-based dry film layer is formed by coating and drying.

Surface treatment is performed on either or both of the first and second links 53, 54 of the rollers 59, 60, and further, either or both of the rollers 59, 60 and the first and second links 53, 54 The surface of the person forms a lubricating film layer. That is, as the surface treatment of the rolls 59 and 60 and the deformation of the lubricating film layer, there are 1) surface treatment of the rolls 59 and 60, and further formation of a lubricating film layer on the surface thereof; 2) surface treatment of the rolls 59, 60 , the lubricating film layer is not formed on the surface; 3) the surface treatment is not performed on the rolls 59, 60, and the lubricating film layer is formed on the surface; 4) the surface treatment of the rolls 59, 60 is not performed, nor is it formed Lubricate the film layer. Similarly, for the surface treatment of the first and second links 53, 54 and the deformation of the lubricating film layer, there are also 1) surface treatment of the first and second links 53, 54 to form a lubricant on the surface thereof. 2) performing surface treatment on the first and second links 53, 54 without forming a lubricating film layer on the surface thereof; 3) not performing surface treatment on the first and second links 53, 54 to form lubrication on the surface The film layer; 4) does not perform surface treatment on the first and second links 53, 54 nor form a lubricating film layer.

The material of the rolls 59, 60, in particular the rolling elements, may be identical or different from the material of the first and second links 53, 54. As the material, it may be either metal or resin. When it is a resin, surface treatment is not performed, and it is necessary to study whether or not a lubricating film layer is formed. The metal material is aluminum, typically aluminum alloy, but titanium, titanium alloy, magnesium alloy, and stainless steel or steel depending on the degree of load resistance. As a resin material, a general engineering plastic such as acrylonitrile butadiene styrene resin (ABS resin), a super engineering plastic such as a fluorine resin such as polytetrafluoroethylene having a low friction coefficient and high durability, and a self-lubricating resin are used. Polyacetal, polyamide, polytetrafluoroethylene, and the like. When the self-lubricating resin is selected, the surface treatment is not performed, and the lubricating film layer is not formed.

Hereinafter, a preferred specific example will be described. The rolling system of the rolls 59, 60 is made of the same metal as the first and second links 53, 54. Typically, the rolling systems of the first and second links 53 and 54 and the rolls 59 and 60 are made of, for example, an Al—Cu-based aluminum alloy from the viewpoint of hardness, weight, and formability.

Surfaces of the first and second links 53, 54 (connected to the rollers 59, 60) The surface is covered by a hard alumite layer by a hard alumite surface treatment. The outer peripheral surface (rolling surface) of the rolls 59 and 60 is covered with the lubricating coating layer 61 by application and drying of the dry film lubricant. The lubricating coating layer 61 is preferably a fluorine-based lubricating coating formed by HANARL (registered trademark) manufactured by Kanto Chemicals Co., Ltd.

By forming the first and second links 53 and 54 with an aluminum alloy having a relatively small specific gravity in the metal, the columnar body joined by the first and second links 53 and 54 can be made lighter. Further, the material of the rolling elements of the rolls 59 and 60 is made of an aluminum alloy similarly to the first and second links 53, 54, but the surfaces of the first and second links 53, 54 are covered with a hard alumite layer. The outer peripheral surfaces of the rolls 59, 60 are covered by the lubricating coating layer 61, that is, the first and second links 53, 54 and the rolls 59, 60 are made of the same material, but the first and second links 53, 54 The surface hardness is higher than the surface hardness of the rolls 59, 60, whereby the aggressiveness of the rolls 59, 60 against the surfaces of the first and second links 53, 54 can be suppressed, and the first and second links 53, 54 are ensured. Higher durability. Further, since the outer peripheral surface (rolling surface) of the rolls 59 and 60 is also covered by the lubricating coating layer 61, the outer peripheral surface can be effectively prevented from being worn compared with the case where the outer peripheral surface is not covered by the lubricating coating layer 61.

That is, in the present embodiment, the first and second links 53, 54 which are high in manufacturing cost and complicated in replacement work are slower than the structural design of the rollers 59, 60, and also ensure high durability of the rollers 59, 60 themselves. In addition, the weight of the arm portion 5, that is, the first and second links 53, 54 is also achieved. Thereby, the durability of the feeding mechanism of the linear motion expansion mechanism can be improved and the weight of the arm portion 5 can be reduced.

Further, in the present embodiment, the outer circumferential surface of the upper and lower rollers 59 and the outer circumferential surface of the right and left rollers 60 are covered by the lubricating coating layer 61. However, since the load due to the weight of the arm portion 5 is mainly applied to the upper and lower rollers 59, Even if only the upper and lower rolls 59 are covered by the lubricating film layer 61, a certain effect is achieved. Further, not all of the plurality of upper and lower rollers 59 are covered by the lubricating coating layer 61, but the uppermost roller 59 and the lowermost roller are generated only by the self-weight of the arm portion 5. 59 is covered by the lubricating film layer 61, and a certain effect is also achieved.

The embodiments of the present invention have been described, but the embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiments can be implemented in various other forms, and various omissions, substitutions and changes can be made without departing from the scope of the invention. The scope of the invention and the scope of the invention are intended to be included in the scope of the invention and the equivalents thereof.

23‧‧‧A pair of side frames

24‧‧‧Cylinder

25‧‧‧Send agency

26‧‧‧Corner frame

56‧‧‧ drive gear

57‧‧‧guide roller

59, 60‧‧‧ Roll

Claims (20)

A linear motion retracting mechanism comprising: a plurality of first links in a flat plate shape, wherein the first and second end portions are bendably coupled to each other; and the plurality of second links in the shape of the groove are opposite to each other at the front and rear end faces a joint portion that joins a front end of the first link and a front end of the second link; and a sending mechanism that firmly engages the front and rear links and moves back and forth The plurality of rollers are arbitrarily supported, and the first and second links are linearly rigidly joined to each other by the rollers when they are fed forward, and form a columnar arm together with the joint portion. When the back is pulled back, the roller is separated from each other and returned to the bent state, and the roller is formed of the same material as the first and second links. The linear motion expansion and contraction mechanism of claim 1, wherein the first and second links are subjected to an abrasion resistant surface treatment, and a lubricating coating layer is formed on the surface of the roller. The linear motion stretching mechanism of claim 2, wherein the surface treatment is a hard alumite treatment. The linear motion stretching mechanism of claim 2, wherein the lubricating coating layer is formed using a fluorine-based dry film lubricant. For example, the linear motion retracting mechanism of patent scope 1 wherein the above roller Both or one of the first and second links described above is subjected to an abrasion resistant surface treatment. The linear motion stretching mechanism of claim 5, wherein the roller is subjected to a surface treatment different from the surface treatment performed on the first and second links. The linear motion stretching mechanism of claim 5, wherein the roller is subjected to the same surface treatment as the surface treatment performed on the first and second links. The linear motion stretching mechanism according to any one of claims 1 to 5, wherein a lubricating film layer is formed on a surface of the roller and either or both of the first and second links. The linear motion stretching mechanism according to claim 8, wherein the roller is formed with a lubricating coating layer different from the type of the lubricating coating layer formed on the first and second links. The linear motion stretching mechanism according to claim 8, wherein the roller is formed with a lubricating coating layer of the same type as the lubricating coating layer formed on the first and second links. A linear motion retracting mechanism comprising: a plurality of first links in a flat plate shape, wherein the first and second end portions are bendably coupled to each other; and the plurality of second links in the shape of the groove are opposite to each other at the front and rear end faces a joint that bendably joins a front end of the first link and a front end of the second link; and a delivery mechanism unit equipped with a plurality of rollers for firmly supporting the first and second link segments and being movable back and forth, and the first and second links are fed by the rollers when being forwardly fed forward The rods are rigidly connected to each other and form a columnar arm portion together with the joint portion, and are separated from each other behind the roller and returned to a curved state when pulled back toward the rear, and the roller system utilizes the first The second link is composed of different materials. The linear motion stretching mechanism according to claim 11, wherein the first and second links are subjected to a surface treatment for abrasion resistance, and a lubricating coating layer is formed on the surface of the roller. The linear motion stretching mechanism of claim 12, wherein the surface treatment is a hard alumite treatment. The linear motion stretching mechanism of claim 12, wherein the lubricating film layer is formed using a fluorine-based dry film lubricant. The linear motion stretching mechanism of claim 11, wherein the roller and the first or second link are both subjected to an abrasion resistant surface treatment. The linear motion stretching mechanism of claim 15, wherein the roller is subjected to a surface treatment different from the surface treatment performed on the first and second links. The linear motion stretching mechanism of claim 15, wherein the roller is subjected to the same surface treatment as the surface treatment performed on the first and second links. The linear motion stretching mechanism according to any one of claims 11 to 15, wherein a lubricating film layer is formed on a surface of the roller and either or both of the first and second links. The linear motion stretching mechanism according to claim 18, wherein the roller is formed with a lubricating coating layer different from the type of the lubricating coating layer formed on the first and second links. A linear motion stretching mechanism according to claim 18, wherein the roller is formed with a lubricating coating layer of the same type as the lubricating coating layer formed on the first and second links.