WO2017188405A1

WO2017188405A1 - Linear extension/retraction mechanism

Info

Publication number: WO2017188405A1
Application number: PCT/JP2017/016843
Authority: WO
Inventors: 尹　祐根; 大輔神田; 啓明松田
Original assignee: ライフロボティクス株式会社
Priority date: 2016-04-27
Filing date: 2017-04-27
Publication date: 2017-11-02
Also published as: JPWO2017188405A1; TW201741098A; JP6573417B2

Abstract

The purpose of the present invention is to reduce the replacement frequency of first and second pieces that are critical components of a linear extension/retraction mechanism. A linear extension/retraction mechanism that has: a plurality of flat, flexibly connected first pieces 53; and a plurality of half-pipe-shaped, flexibly connected second pieces 54. Heads of the plurality of first pieces and heads of the plurality of second pieces are joined by a joining part 55. A support mechanism part 58 supports the first and second pieces such that the first and second pieces can move forward and backward, makes the first and second pieces adjoin when the first and second pieces move forward, and makes the first and second pieces separate when the first and second pieces move backward. The first and second pieces form a stiff straight line when adjoined and return to a flexible state when separated. Abrasion prevention pads 550 that comprise a softer material than the first and second pieces and that are for preventing abrasion at contact surfaces of the first and second pieces at which the first and second pieces contact each other are mounted at one section of the contact surfaces of the first and second pieces.

Description

Linear motion expansion / contraction mechanism

The embodiment of the present invention relates to a linear motion expansion / contraction mechanism.

Conventionally, articulated robot arm mechanisms have been used in various fields such as industrial robots. The inventors have developed a linear motion expansion / contraction mechanism applicable to such an articulated robot arm mechanism (Patent Document 1). The linear motion expansion / contraction mechanism is composed of a plurality of metal pieces having a flat plate shape (first frame) connected in a hinge structure so as to be bent, and a metal having a half-angle tube shape connected in a hinge shape on the bottom plate so as to be bent. A plurality of frames (second frames). The first and second frames are joined at the tip, and when sent forward, the first and second frames are overlapped to ensure a rigid state, and are configured as columnar arms having a certain rigidity. When pulled back, the first and second frames are separated, return to a bendable state, and housed inside the column. The adoption of this linear motion expansion / contraction mechanism in the articulated robot arm mechanism is an extremely useful structure because it eliminates the need for an elbow joint and can easily eliminate singularities.

It is required to increase the rigidity of the arm by firmly joining the first and second frames. As the arm expands and contracts, the strong collision between the first and second frames is repeated. Therefore, wear of the contact surfaces of the first and second frames is inevitable. Contact surface wear reduces the stiffness of the arm. Therefore, early replacement of the worn first and second frames is required.

The replacement work for the first and second frames requires a lot of man-hours because it is necessary to disassemble the arm mechanism because they are internal structural parts. The first and second frames are metal cutting products and are relatively expensive.

Japanese Patent No. 5435679

The purpose is to reduce the replacement frequency of the first and second frames, which are important parts of the linear motion expansion / contraction mechanism.

The linear motion expansion / contraction mechanism according to the present embodiment includes a plurality of flat plate-shaped first frames connected to bendable and a plurality of semi-tubular second frames connected to bendable. The heads of the plurality of first frames and the heads of the plurality of second frames are combined at the combining unit. The support mechanism supports the first and second frames so as to be movable back and forth, and joins the first and second frames when moving forward, and separates them when the first and second frames move backward. Let The first and second frames are straightened when they are joined together, and the first and second frames return to the bent state when separated from each other. At least a part of at least one contact surface of at least one of the first and second pieces, or at least one contact point where the first and second pieces contact each other, in order to prevent wear of the contact surfaces of the first and second pieces. An anti-abrasion pad made of a material having a hardness lower than that of the first and second frames is attached and / or a coating agent is coated.

FIG. 1 is a perspective view showing an appearance of a robot arm mechanism equipped with a linear motion expansion / contraction mechanism according to the present embodiment. FIG. 2 is a side view of the robot arm mechanism of FIG. FIG. 3 is a side view showing the internal structure of the robot arm mechanism of FIG. FIG. 4 is a diagram showing the configuration of the robot arm mechanism of FIG. FIG. 5 is a diagram illustrating the first frame of FIG. FIG. 6 is a diagram illustrating the second frame in FIG. 3. FIG. 7 is a perspective view showing an anti-wear pad attached to the second frame of FIG. FIG. 8 is a view for explaining the joining process of the first and second frames in FIG. FIG. 9 is a view for explaining a joining process of the lock mechanism of FIG. FIG. 10 is a diagram showing a coating portion formed from an antiwear agent.

Hereinafter, the linear motion expansion / contraction mechanism according to this embodiment will be described with reference to the drawings. In addition, the linear motion expansion-contraction mechanism which concerns on this embodiment can be used as an independent mechanism (joint). In the following description, a polar coordinate type robot arm mechanism in which one joint portion of the plurality of joint portions is configured by the linear motion extension mechanism according to the present embodiment will be described as an example. The linear motion expansion / contraction mechanism according to the present embodiment can also be applied to a cylindrical coordinate type robot arm mechanism. Of course, the linear motion expansion / contraction mechanism according to the present embodiment can also be applied to mechanisms other than the robot arm mechanism. In the following description, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

FIG. 1 shows the appearance of a robot arm mechanism equipped with a linear motion expansion / contraction mechanism according to this embodiment. FIG. 2 is a side view of the robot arm mechanism of FIG. FIG. 3 is a side view showing the internal structure of the robot arm mechanism of FIG. The robot arm mechanism includes a base 1, a turning part (supporting part) 2, a shoulder part 4, an arm part 5, and a wrist part 6. The turning part 2, the shoulder part 4, the arm part 5, and the wrist part 6 are arranged in order from the base 1. The turning part 2, the shoulder part 4, and the arm part 5 correspond to the joint parts J1, J2, and J3, respectively. The wrist 6 is assembled with joints J4, J5, and J6. The base 1 is typically provided with a swivel portion 2 that forms a cylindrical body vertically. The turning part 2 accommodates the first joint part J1. The first joint portion J1 is a rotational joint that rotates about the rotation axis RA1. The rotation axis RA1 is parallel to the vertical direction. The swivel unit 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 with a cylindrical housing 31. The upper frame 22 is connected to the rotating portion of the first joint portion J1, and rotates about the rotation axis RA1. The upper frame 22 is covered with a cylindrical housing 32. With the rotation of the first joint portion J1, the upper frame 22 rotates with respect to the lower frame 21, whereby the arm portion 5 turns. First and

second frame rows

51 and 52 of a third joint portion J3 serving as a linear motion extending / contracting mechanism to be described later are housed in the hollow interior of the swivel portion 2 forming a cylindrical body.

The shoulder part 4 is installed on the upper part of the turning part 2. The shoulder portion 4 includes a second joint portion J2 that is a rotary joint. The arm portion 2 rotates around the rotation axis RA2 by the rotation of the second joint portion J2. The rotation axis RA2 of the second joint portion J2 is orthogonal to the rotation axis RA1. The shoulder part 4 has a pair of side frames 23 as a fixing part (support part) of the second joint part J2. The pair of side frames 23 are connected to the upper frame 22. The pair of side frames 23 is covered with a bowl-shaped cover 33. The pair of side frames 23 supports a cylindrical body 24 as a rotating portion of the second joint portion J2 that also serves as a motor housing. A support mechanism 25 is attached to the peripheral surface of the cylindrical body 24. The support mechanism 25 is covered with a cylindrical cover 34. The gap between the bowl-shaped cover 33 and the cylindrical cover 34 is covered with a U-shaped bellows cover 14 having a U-shaped cross section. The U-shaped bellows cover 14 expands and contracts following the up-and-down movement of the second joint portion J2. The support mechanism 25 holds a drive gear 56, a guide roller 57, and a roller unit 58. The roller unit 58 includes a plurality of rollers 59 and is disposed in front of the support mechanism 25. A drive gear 56 is disposed behind the roller unit 58. The drive gear 56 is connected to a motor unit (not shown). The motor unit generates power for rotating the drive gear 56. The linear gear 539 of the first frame 53 is meshed with the drive gear 56. The linear gear 539 is formed along the connecting direction at the inner surface of the first frame 53, in other words, at the center of the width of the surface to be joined to the second frame 54. When the plurality of first frames 53 are aligned in a straight line, the adjacent linear gears 539 are connected in a straight line to form a long linear gear. The linear gear 539 connected in a straight line forms a rack and pinion mechanism together with the drive gear 56. A guide roller 57 is disposed above the drive gear 56 at a distance substantially equivalent to the thickness of the first frame 53. As a result, the drive gear 56 is engaged with the linear gear 539 of the first frame 53 pressed by the guide roller 57, so that the drive gear 56 can smoothly feed the first frame row 51. As the cylindrical body 24 rotates, the support mechanism 25 rotates, and the arm portion 5 supported by the support mechanism 25 rotates upward or downward.

The third joint J3 is a linear motion extending and retracting mechanism. The linear motion expansion / contraction mechanism has a structure newly developed by the inventors, and the movable range is clearly longer than that of a conventional prismatic joint. Although the arm portion 5 of the third joint portion J3 is freely bendable, the bending is limited when the arm portion 5 is fed forward from the support mechanism 25 at the base of the arm portion 5 along the central axis (extension / retraction center axis RA3), and linear rigidity is achieved. Is secured. When the arm part 5 is pulled back, the bending is recovered. The arm unit 5 includes a first frame row 51 and a second frame row 52. The first frame row 51 is composed of a plurality of first frames 53 that are connected to be freely bent. Each first frame 53 is formed in a substantially flat plate shape. The plurality of first frames 53 are connected in a row so as to be freely bent by a plurality of hinge portions. Each hinge portion connects adjacent pairs of first frames 53 at their end portions. The second frame row 52 includes a plurality of second frames 54. Each second frame 54 is a tube having a circular or polygonal cross-sectional shape or a semi-tube shape thereof. That is, the semi-tubular shape is either a semicircular ridge shape or a half-square ridge shape. Typically, each second piece 54 has a half-angled bowl shape in which a bottom plate and a two-side plate are combined at a right angle. The plurality of second frames 54 are connected in a row at a plurality of hinge portions so as to be freely bent. Each hinge portion connects adjacent pairs of second frames 54 at the end portions of the bottom plate. The bending of the second frame row 52 is locked at a position where the end surfaces of the side plates of the second frame 54 come into contact with each other. At that position, the plurality of second frame rows 52 are linearly arranged. The first first frame 53 of the first frame sequence 51 and the second second frame 54 of the second frame sequence 52 are connected by a combined frame 55. For example, the combined frame 55 has a shape obtained by combining the first frame 53 and the second frame 54.

The first and

second frame rows

51 and 52 are pressed and joined to each other by the roller 59 when passing through the roller unit 58 of the support mechanism 25. By joining, the first and

second frame rows

51 and 52 exhibit linear rigidity and constitute a columnar arm portion 5. When the drive gear 56 rotates in the forward direction, the first and

second frame rows

51 and 52 become columnar bodies and are sent forward. When the drive gear 56 rotates in the reverse direction, the columnar body is pulled back and separated into the first and

second frame rows

51 and 52 between the roller unit 58 and the drive gear 56. The separated first and

second frame rows

51 and 52 are returned to a bendable state. The first and

second frame rows

51, 52 that have returned to the bendable state are both bent in the same direction (inner side) and stored vertically in the turning unit 2. At this time, the first frame row 51 is stored in a state of being substantially aligned with the second frame row 52 substantially in parallel.

The wrist part 6 is attached to the tip of the arm part 5. The wrist 6 is equipped with fourth to sixth joints J4 to J6. The fourth to sixth joints J4 to J6 are each provided with three orthogonal rotation axes RA4 to RA6. The fourth joint portion J4 is a rotary joint that rotates about a fourth rotation axis RA4 that substantially coincides with the expansion / contraction center axis RA3, and the end effector swings by the rotation of the fourth joint portion J4. The fifth joint portion J5 is a rotary joint that rotates about a fifth rotation axis RA5 orthogonal to the fourth rotation axis RA4. The end effector tilts back and forth by the rotation of the fifth joint J5. The sixth joint portion J6 is a rotary joint that rotates about a sixth rotation axis RA6 that is orthogonal to the fourth rotation axis RA4 and the fifth rotation axis RA5. The end effector is axially rotated by the rotation of the sixth joint J6.

The end effector (hand effector) is attached to an adapter 7 provided at the lower part of the rotating part of the sixth joint part J6 of the wrist part 6. The end effector is a part having a function of directly acting on a work target (work) by the robot, and various tools such as a gripping part, a vacuum suction part, a nut fastener, a welding gun, and a spray gun exist. 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 an arbitrary posture by the fourth, fifth, and sixth joint portions J4, J5, and J6. In particular, the length of the expansion / contraction distance of the arm portion 5 of the third joint portion J3 enables the end effector to reach a wide range of objects from the proximity position of the base 1 to the remote position. The third joint portion J3 is a characteristic point that is different from the conventional linear motion joint in the linear expansion / contraction operation realized by the linear motion expansion / contraction mechanism constituting the third joint portion J3 and the length of the expansion / contraction distance.

Fig. 4 shows the configuration of the robot arm mechanism in graphical symbols. In the robot arm mechanism, three position degrees of freedom are realized by the first joint portion J1, the second joint portion J2, and the third joint portion J3 that form the three base axes. In addition, three posture degrees of freedom are realized by the fourth joint portion J4, the fifth joint portion J5, and the sixth joint portion J6 constituting the wrist three axes. As shown in FIG. 5, 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 with respect to the first joint portion J1 with respect to the two directions of the rotation axis RA1 and an 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 provided in a direction orthogonal to the rotation axis RA2. The third joint portion J2 is offset with respect to the second joint portion J2 with respect to two directions of the rotation axis RA1 and an 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 rotary joint portion of the base three axes of the plurality of joint portions J1-J6 is replaced with a linear motion expansion / contraction joint portion J3. The second joint J2 is offset in two directions with respect to the first joint J1. The third joint portion J3 is offset in two directions with respect to the second joint portion J2. Thus, the robot arm mechanism according to the present embodiment realizes elimination of singularities.

(First frame 53)
FIG. 5 is a diagram showing the structure of the first frame 53 of FIG. The first frame 53 is a substantially flat body as a whole. The first frame 53 is formed by integrally forming a pair of support blocks 532 and a bearing block 533 on a flat rectangular main body 531. The pair of support blocks 532 are provided to protrude forward on both sides of the front end of the main body portion 531. The bearing block 533 is provided to protrude rearward at the center of the rear end of the main body portion 531. A pair of shaft holes 534 are passed through the pair of support blocks 532 at the front end in parallel with the width direction of the first frame 53. A shaft hole 535 is also passed through the bearing block 533 at the rear end in parallel with the width direction of the first frame 53. The pair of shaft holes 534 and the shaft holes 535 are continuously formed in a state where the bearing block 533 at the rear end of the other first frame 53 is fitted between the pair of support blocks 532 at the front end of the first frame 53. Connected. A shaft (not shown) is inserted into the continuously connected through-holes, and the front and rear first frames 53 are connected to each other in a freely rotatable manner. A linear gear 539 is provided at the center of the width of the back surface of the first frame 53 across the front and rear in parallel with the connecting direction (length direction). A linear gear 539 is provided at the center of the back surface of the first frame 53, and a pair of quadrangular pyramid-shaped projections (pinhole blocks) 536 project vertically on both sides of the back surface. The pair of pinhole blocks 536 are located on both sides near the center of the first frame 53 in the front-rear direction (length direction). A lock pin hole 537 is formed in the pin hole block 536 along the front-rear direction.

In FIG. 5, the contact surface of the first frame 53 that contacts the second frame 54 in a state where the first and

second frames

53 and 54 are joined is indicated by hatching. As shown in FIG. 5, the contact surfaces of the first frame 53 are the back side portions of the first frame 53 and the front and rear end surfaces of the pinhole block 536.

(2nd frame 54)
FIG. 6 is a diagram showing the structure of the second frame 54 of FIG. The second frame 54 has a half-angle tube shape. The second frame 54 includes a bottom plate 541 and a pair of side plates 540 having the same size and shape. A pair of support blocks 542 are provided on both sides of the front end of the bottom plate 541. A bearing block 543 projects from the center of the rear end of the bottom plate 541. A pair of shaft holes 544 are passed through the pair of support blocks 542 at the front end in parallel with the width direction of the second frame 54. A shaft hole 545 is also passed through the bearing block 543 at the rear end in parallel with the width direction of the second frame 54. The pair of shaft holes 544 and 545 are continuously formed in a state in which the bearing block 543 at the rear end of the other second piece 54 is fitted between the pair of support blocks 542 at the front end of the second piece 54. Connected. A shaft is inserted into the continuously connected through hole, and the front and rear second pieces 54 are rotatably connected to each other. A lock pin block 546 protrudes inward from the upper front end of each side plate 540 of the second frame 54. The lock pin block 546 has a rectangular parallelepiped shape, and a lock pin 547 is provided on the front side surface thereof. The lock pin 547 forms a cylindrical body and projects forward in parallel with the connecting direction. A chuck block 548 protrudes inwardly from the upper rear end of each side plate 540 of the second frame 54. The chuck block 548 has a quadrangular pyramid shape, and its inclined surface faces rearward. In the second frame row 22, the chuck block 548 of the front second frame 54, together with the lock pin block 546 of the rear second frame 54, constitutes a receiving portion that receives the pinhole block 536 forward and backward.

In FIG. 6, the contact surface of the second frame 54 that contacts the first frame 53 in a state where the first and

second frames

53 and 54 are joined is indicated by hatching. As shown in FIG. 6, the contact surface of the second piece 54 is the upper end surface of the pair of side plates 540, the front end surface of the lock pin block 546, and the rear end surface of the chuck block 548.

(Lock mechanism)
The linear motion expansion / contraction mechanism has a lock mechanism for maintaining the joined state of the first and

second frames

53 and 54. The locking mechanism includes a chuck block 548 and a lock pin block 546 of the second frame 54, and a pinhole block 536 of the first frame 53.

When the arm portion 5 is extended, the pinhole block 536 of the first frame 53 is narrowed by the receiving portions of the front and rear second frames 54, whereby the first and

second frames

53 and 54 are joined. The joined state of the first and

second frames

53 and 54 is maintained in a state where the lock pin 547 of the second frame 54 is inserted into the pin hole 537 of the first frame 53. The lock pin 547 of the second frame 54 is arranged so that the second frame 54 passes through the last roller 59 of the roller unit 58 and is aligned linearly with the second frame 54 in front of the second frame 54. It is inserted into the pinhole 537. The state in which the lock pin 547 of the second frame 54 is inserted into the pin hole 537 of the first frame 53 is a state where the front and rear second frames 54 are linearly aligned, that is, the rear end portion of the arm portion 5 is a roller. It is maintained in a state of being firmly held by the unit 58.

When the arm portion 5 contracts, the second frame 54 returns to a bendable state behind the roller unit 58 and is pulled downward by gravity. On the other hand, the first frame 53 is pulled rearward by the drive gear 56 while maintaining the horizontal posture. When the second frame 54 is pulled downward and the first frame 53 is pulled rearward, the lock pin 547 of the second frame 54 is pulled out from the pin hole 537 of the first frame 53, and the second frame 54 is received by the front and rear. The part opens the pinhole block 536 of the first frame 53, whereby the joined state of the first and

second frames

53 and 54 is released, and the first frame 53 and the second frame 53 are separated from each other so as to be bent.

As described above, the expansion and contraction of the arm portion 5 constituting the linear motion expansion / contraction mechanism is realized by joining when the first and

second frames

53 and 54 are sent out and separating when the first and

second frames

53 and 54 are pulled back. When the first and

second frames

53 and 54 are joined, the contact surfaces of the first and

second frames

53 and 54 are worn by the collision of the second frame 54 against the first frame 53. Further, in the state where the first and

second pieces

53 and 54 are joined, the contact surface is worn due to minute vibrations caused by the expansion and contraction of the arm portion 5 and the like. The wear on the contact surfaces of the first and

second frames

53 and 54 changes the outer dimensions of the first and

second frames

53 and 54. Changes in the external dimensions of the first and

second frames

53 and 54 may decrease the rigidity of the arm unit 5 and hinder the linearity of the arm unit 5. The linear motion expansion / contraction mechanism according to this embodiment reduces wear on the contact surfaces of the first and

second frames

53 and 54. Specifically, the wear prevention pad is attached to at least a part of at least one of the contact surface of the first frame 53 and the contact surface of the second frame 54. A coating agent is coated on at least a part of at least one of the contact surface of the first piece 53 and the contact surface of the second piece 54 together with or in place of the wear prevention pad.

FIG. 7 is a perspective view showing the anti-wear pad attached to the first frame 53 of FIG. As shown in FIG. 7, the wear prevention pad 550 is preferably attached to the rear side surface of the chuck block 548. The wear prevention pad 550 has a disk shape, for example, and is attached to the chuck block 548 by adhesion or the like. The wear prevention pad 550 has a surface hardness of the first and second tops 53 and 54, that is, a material (for example, AlCu-based aluminum alloy), or a surface coating layer (for example, a hard anodized layer) of the first and second tops 53 and 54. It is made of a metal or resin having a lower hardness. In the case of resins, in addition to natural rubber, fluorine resins such as polytetrafluoroethylene, which has a low friction coefficient and high durability, ultrahigh molecular weight high density polyethylene, and polyacetal, polyamide, polytetrafluoroethylene as self-lubricating resins. Fluoroethylene is used. The collision, contact and sliding between the first and

second frames

53 and 54 preferentially wear the wear prevention pad 550 made of a material having a hardness lower than that of the first and

second frames

53 and 54.

FIG. 8 is a view for explaining the joining process of the arm portion 5 of FIG. FIG. 9 is a schematic view showing the locking mechanism of FIG. FIGS. 9A, 9B, and 9C are schematic views showing the locking mechanisms of FIGS. 8A, 8B, and 8C, respectively. As shown in FIGS. 8A, 8B, 9A, and 9B, when the second frame 54-1 is displaced from the bent state to the linear state, The rear side surface of the chuck block 548-1 of the top 54-1 collides with the front side surface of the pinhole block 536-1 of the first top 53-1, and the contact surface wears. Further, as shown in FIGS. 8C and 9C, when the rear second frame 54-2 is displaced from the bent state to the linear state, the rear second frame 54-2 is locked. The pin block 546-2 collides with the pinhole block 536-1 of the first frame 53-1, the pinhole block 536-1 of the first frame 53-1 is pushed forward, and the front side surface thereof is the second frame 54-1. -1 of the chuck block 548-1 is pressed. Since the rear side surface of the chuck block 548-1 and the front side surface of the pinhole block 536-1 are inclined with respect to the telescopic axis RA3, the pinhole block 536-1 is arranged with respect to the rear side surface of the chuck block 548-1. The front side slips and wears.

As described above, the bonding strength between the front side surface of the pinhole block 536 of the first frame 53 and the rear side surface of the chuck block 548 of the second frame 54 is higher than that of the other contact surfaces, and is applied per unit area. The stress is high and therefore wear progresses faster compared to other contact surfaces. Wearing the wear prevention pad 550 on the rear side surface of the chuck block 548 of the second frame 54 most effectively reduces wear on the contact surfaces of the first and

second frames

53 and 54. Specifically, the wear prevention pad 550 on the rear side surface of the chuck block 548 of the second frame 54 prevents wear of the rear side surface of the chuck block 548 of the second frame 54, and the pinhole block 536 of the first frame 53 Reduce front side wear. Further, the wear prevention pad 550 reduces the impact of the second frame 54 colliding with the first frame 53, and also reduces the wear of other contact surfaces. Further, the wear prevention pad 550 functions as an anti-slip and reduces the sliding wear generated on the contact surfaces of the first and

second pieces

53 and 54.

In addition, the mounting position of the wear prevention pad 550 is not limited to this. For example, the wear prevention pad 550 may be attached to the front side surface of the pinhole block 536 of the first frame 53. In this case, an effect equivalent to that obtained when the wear prevention pad 550 is mounted on the rear side surface of the chuck block 548 of the second frame 54 can be obtained. Further, if the lock mechanism can be maintained with the lock pin 547 of the second frame 54 inserted into the pin hole 537 of the first frame 53, the first and

second frames

53, 54 are joined to each other in the chuck block 548. The rear side surface and the front side surface of the pinhole block 536 may not be in contact with each other. Therefore, mounting the wear prevention pad 550 on the rear side surface of the chuck block 548 of the second frame 54 or the front side surface of the pinhole block 536 of the first frame 53 causes the wear prevention pad 550 to be mounted on the other contact surface. There is no effect on the outer shape of the frame as compared with the case where the wear prevention pad 550 is worn. Of course, the wear prevention pad 550 may be attached to the contact surfaces of the first and

second frames

53 and 54 other than the rear side surface of the chuck block 548 and the front side surface of the pinhole block 536.

Further, in order to reduce wear of the first and

second frames

53 and 54, at least a part of at least one of the contact surface of the first frame 53 and the contact surface of the second frame 54 is prevented from wearing. An agent, typically a resin coating agent, preferably a fluorine-based resin coating agent such as Hanar (registered trademark) may be coated. FIG. 10 is a view showing a coating portion formed by the wear inhibitor 553. As shown in FIG. 10, for example, a resin coating agent 553 may be coated on the entire contact surface of the second frame 54.

In addition, a plurality of sharp protrusions may be formed on at least one of the contact surface of the first frame 53 and the contact surface of the second frame 54, and the tips (contact points) of the sharp protrusions may be in contact with each other. In that case, a minute anti-abrasion pad may be attached to the tip of at least one sharp projection, or a coating agent may be coated.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

54 ... second frame, 540 ... side plate, 541 ... bottom plate, 542 ... support block, 543 ... bearing block, 544,545 ... shaft hole, 546 ... lock pin block, 547 ... lock pin, 548 ... chuck block, 550 ... wear Prevention pad.

Claims

A plurality of flat plate-shaped first frames connected to bendable;
A plurality of tube-shaped or semi-tube-shaped second pieces connected to bendable;
A coupling unit coupling the tops of the plurality of first frames and the tops of the plurality of second frames;
The first and second frames are supported movably in the front-rear direction, and the first and second frames are linearly stiffened when the first and second frames move forward. A support mechanism that separates the second frame from the first frame in order to join the two frames and return the first and second frames to the bent state when the first and second frames move backward; Equipped,
At least a part of at least one contact surface or at least one contact point of the first and second frames where the first and second frames contact each other prevents wear of the contact surfaces of the first and second frames. In order to achieve this, a linear motion expansion / contraction mechanism comprising a wear prevention pad made of a material having a hardness lower than that of the first and second pieces and / or coated with a coating agent.
The first frame is provided with a quadrangular pyramid-shaped projection on the surface to be joined to the second frame, and the projection is engaged with the front and rear sides of each of the front and rear ends of the second frame. A receiving part is provided, and the receiving part of the second piece before and after the second piece joins the first piece sandwiches the protrusion from the front and back;
The receiving portion provided at the rear end of the second frame is provided with the wear prevention pad on the surface contacting the front side surface of the projection and / or coated with the coating agent. The linear motion expansion / contraction mechanism according to claim 1.
The first frame is provided with a quadrangular pyramid-shaped projection on the surface to be joined to the second frame, and the projection is engaged with the front and rear sides of each of the front and rear ends of the second frame. A receiving part is provided, and the receiving part of the second piece before and after the second piece joins the first piece sandwiches the protrusion from the front and back;
2. The linear motion extension / contraction mechanism according to claim 1, wherein the wear prevention pad is attached to the front side surface of the protrusion and / or the coating agent is coated.
The linear motion expansion / contraction mechanism according to claim 1, wherein the coating agent is coated on an entire surface of at least one of the first and second frames.
The linear motion expansion / contraction mechanism according to claim 1, wherein the wear prevention pad is a resin pad.
The linear motion expansion / contraction mechanism according to claim 1, wherein the wear prevention pad is a metal pad.
The linear motion expansion / contraction mechanism according to claim 1, wherein the coating agent contains fluorine as a main component.
2. The linear motion extension / contraction mechanism according to claim 1, wherein the wear prevention pad has a disk shape.