JP2012201432A - Gripping device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gripping device that can grasp an arm's elevation position where a workpiece lands on a placement surface even if heights of placement surfaces of a conveyance source and a conveyance destination are different from each other.SOLUTION: The gripping device 20 is provided with a ranging sensor 40 at the lower end of a pair of arms 21 for measuring a distance of the workpiece W to the placement surface (arm height h). The gripping device 20 stores the gripping height when gripping the workpiece W in a memory. When the workpiece W is placed on the placement surface f, the arm height h detected by the ranging sensor 40 is compared with the gripping height stored in the memory so as to grasp the arm's elevation position.

Description

  The present invention relates to a gripping device that grips a workpiece.

  Conventionally, a workpiece is gripped by a gripping device and conveyed to a predetermined place. At the transport destination, it is required to land smoothly without giving an impact to the workpiece when the workpiece is lowered. Therefore, for example, in Patent Document 1, a photoelectric sensor is arranged at a predetermined height position of the automatic guided vehicle. In Patent Document 1, when the automatic guided vehicle lifts the roll (work) by a certain stroke, the photoelectric sensor detects the lower surface of the roll and determines the lift-down stroke for unloading from the lower surface of the roll to the floor surface. ing.

  Also, for example, in Patent Document 2, in a forklift that lifts and lowers a side clamp that grips a transferred object (work), a contact part that contacts the transferred object and an arm part that supports the contact part can be relatively moved by a linear guide. It is configured. Further, a protrusion is provided on the contact portion, and a limit switch is provided on the arm portion. At the time of unloading, it is detected by the protrusion and the limit switch that the transferred object contacts the placement surface and the distance of the relative movement between the contact part and the arm part has reached a predetermined dimension. In this way, the transfer object is reliably brought into contact with the placement surface by detecting the change of the limit switch and stopping the lowering of the side clamp portion.

JP 2005-29357 A JP 2001-341807 A

  In the automatic guided vehicle disclosed in Patent Document 1, the work can be smoothly lowered onto the floor surface having a certain height. However, there is a problem that when the floor height of the transport source and the transport destination is different, it is not possible to correspond to a predetermined height position such as a shelf, and smooth landing according to the floor surface height cannot be performed. On the other hand, in the forklift disclosed in Patent Document 2, the transferred object can be landed on the mounting surfaces having different heights. However, since it detects that the relative movement of the contact part and the arm part has reached a predetermined dimension, it cannot detect the moment when the transferred object contacts the placement surface. In other words, there is a problem that the transported object comes into contact with the placement surface or the lift position cannot be accurately grasped.

  The present invention has been made in view of the above problems, and an object of the present invention is to raise and lower the arm where the workpiece lands on the placement surface even if the height of the placement surface of the conveyance source and the conveyance destination is different. The object is to provide a gripping device that can be grasped.

  In order to solve the above problems, the present invention provides an arm for gripping a workpiece, arm lifting means for lifting the arm, and an arm height for detecting the relative height of the arm with respect to the placement surface on which the workpiece is placed. A detection means, a grip height storage means for storing the grip height obtained from the relative height of the arm detected by the arm height detection means when gripping the workpiece placed on the placement surface, and the grip height Comparing means for comparing the grip height stored in the storage means with the arm height detected by the arm height detecting means is provided.

  According to the present invention, when the arm height detecting means detects the relative height of the arm from the placement surface on which the work is placed, and grips the work whose arm height is stored in the grip height storage means. The gripping height can be compared by the comparison means, and it can be grasped according to the placement surface height of the conveyance destination whether the workpiece is in the up-and-down position of the arm contacting the placement surface.

  Furthermore, the present invention is characterized in that, in the above gripping device, the gripping device uses the relative height of the arm from the placement surface detected when gripping the workpiece as the gripping height. As a result, the gripping height can be directly detected, resulting in a simpler configuration.

  Further, according to the present invention, in the above gripping device, the comparison means compares the grip height stored in the grip height storage means with the arm height detected by the arm height detection means when the arm is lowered by the arm lifting / lowering means. And a control means for stopping the lowering of the arm when it is determined that the grip height is equal to the arm height. Thereby, since the descent | fall of an arm stops according to the position where the workpiece | work grasped | ascertained by the comparison means contacts a mounting surface, it can unload smoothly, without giving an impact to a workpiece | work.

  Still further, the arm of the present invention is a pair of arms, and a pair of grip plates that abut the workpiece, and the arm is connected to and supported by the grip plate. When the grip plate is close to the arm, the grip plate And a link mechanism for swinging the gripping plate downward when the gripping plate is separated from the arm. According to this, since the grip plate is swung up and down by the link mechanism, the grip plate can be brought close to the arm and lift the workpiece slightly when gripping the workpiece. Further, when the work is placed, the grip plate is separated from the arm and swings downward, so that the work can be slightly lowered and landed gently on the placement surface.

  In the present invention, the arm height detecting means may be provided at the lower end of the arm, and the arm elevating means may further lower the arm by the vertical movement amount by which the gripping plate swings upward with respect to the arm by the link mechanism. Thereby, even if the workpiece swings upward by the link mechanism, the grip can be released after the workpiece is landed on the placement surface.

  In the present invention, arm height detection means may be provided at the lower end of the gripping plate. Thus, the arm height can be detected by the arm height detecting means including the vertical movement amount by which the workpiece swings up and down with respect to the arm by the link mechanism.

  The present invention can provide a gripping device that can grasp the lift position of an arm on which a workpiece lands on a placement surface even if the placement surfaces of the conveyance source and the conveyance destination are different.

It is a side view of a clamp lift which has a grasping device concerning a 1st embodiment of the present invention. It is a perspective view showing an outline of a grasping device concerning a 1st embodiment of the present invention. It is a front view showing an outline of a grasping device concerning a 1st embodiment of the present invention. It is a front view which shows the cargo handling work of the holding | gripping apparatus which concerns on the 1st Embodiment of this invention. It is a front view which shows the cargo handling work of the holding | gripping apparatus which concerns on the 1st Embodiment of this invention. It is a front view which shows the cargo handling work of the holding | gripping apparatus which concerns on the 1st Embodiment of this invention. It is a front view which shows the cargo handling work of the holding | gripping apparatus which concerns on the 2nd Embodiment of this invention. It is a front view which shows the cargo handling work of the holding | gripping apparatus which concerns on the 2nd Embodiment of this invention. It is a front view which shows the outline | summary of the holding | gripping apparatus which concerns on the example of a change of this invention.

(First embodiment)
Hereinafter, the gripping device according to the first embodiment will be described with reference to the drawings.
As shown in FIG. 1, the clamp lift 1 is provided with a mast 3 in front of the vehicle. The mast 3 is provided with a hydraulic cylinder 7 for raising and lowering the mast 3. On the front surface of the mast 3, a gripping device 20 having an arm 21 via a bracket 10 is provided extending forward. The mast 3 and the hydraulic cylinder 7 are arm elevating means for elevating the bracket 10 and the gripping device 20 up and down.

  As shown in FIG. 2, the gripping device 20 includes a pair of arms 21 and a pair of gripping plates 22. The pair of grip plates 22 is provided between the pair of left and right arms 21 facing each other. The arm 21 has a rectangular plate shape, and the longitudinal direction of the arm 21 coincides with the vehicle longitudinal direction of the clamp lift 1. The rear end of the arm 21 is connected to an actuator 15 provided on the bracket 10. When the actuator 15 is driven, the pair of arms 21 changes the distance between the arms 21 in the left-right direction. The actuator 15 may be a cylinder type or a ball screw type, for example.

  Near the front end portion and the rear end portion of the arm 21, a flange portion 21 </ b> A that stands up toward the inner side of the opposing arm 21 is provided. Each flange portion 21A is provided with two through holes. A pin 23 is inserted into each through hole. One end of each of the four link bars 35 is rotatably supported by the four pins 23. Further, a protruding portion 21B is provided at a position slightly below the center of the flange portion 21A in the vertical direction. A coil spring 30 is supported at one end of the protrusion 21B. The link bar 35 and the pin 23 constitute a link mechanism. Moreover, the coil spring 30 of this embodiment is a tension spring.

  The other end of the link bar 35 is rotatably connected to a flange portion 22A provided on the grip plate 22 via a pin 23. The other end of the coil spring 30 is supported by a protrusion 22B provided at a position slightly above the center of the flange 22A. The grip plate 22 is supported so as to be swingable up and down with respect to the arm 21 via the pin 23 and the link bar 35 of the flange portion 22A. As shown in FIG. 3, the arm 21 is provided with a stopper 21C on the flange portion 21A. The stopper 21 </ b> C restricts the link bar 35 from rotating below a predetermined angle. The stopper 21 </ b> C of the present embodiment regulates the rotation of the link bar 35 downward from a position inclined about 30 degrees upward from the horizontal plane.

  The grip plate 22 has a gap inside the arm 21. The grip plate 22 is connected to and supported by the arm 21 by a link bar 35, a pin 23, and a stopper 21C. The grip plate 22 comes close to the arm 21 by the link bar 35 and the pin 23 when the grip plate 22 is pressed to the arm 21 side in contact with a workpiece or the like. Further, when the link bar 35 tilts upward, the grip plate 22 swings upward with respect to the arm 21. When the force that pushes the gripping plate 22 toward the arm 21 is removed, the gripping plate 22 swings downward with respect to the arm 21 and is separated from the arm 21.

  One arm 21 is provided with a distance measuring sensor 40 at the front lower end. Here, an optical distance measuring sensor is used. The distance measuring sensor 40 is an arm height detecting unit that can measure the distance from the lower end of the arm 21 to the surface below the arm, that is, the relative height of the arm with respect to the surface on which the workpiece is placed. The distance measuring sensor 40 is connected to a control device 50 provided on the vehicle body of the clamp lift 1 shown in FIG. The control device 50 includes a memory 50 </ b> A that temporarily stores the distance from the lower end of the arm 21 detected by the distance measuring sensor 40 to the floor surface, that is, the height of the arm 21. The memory 50A is a grip height storage unit. Further, the control device 50 controls the drive of each part including the actuator 15 of the clamp lift 1. The control device 50 of this embodiment is also a comparison unit that compares the height of the arm 21 stored in the memory 50 </ b> A with the arm height detected by the distance measuring sensor 40.

Next, cargo handling work by the gripping device 20 of this embodiment will be described. Here, a case will be described in which the workpiece W placed on the floor surface F, which is the placement surface of the transport source, is transported to the placement surface f, which is the transport destination.
When the workpiece W shown in FIG. 2 is gripped by the gripping device 20 and transported to a predetermined transport destination, the clamp lift 1 is first swung to the front of the transport source workpiece W. Next, the actuator 15 is driven to widen the distance between the pair of arms 21 larger than the width of the workpiece W. Then, the clamp lift 1 is advanced to position the grip plate 22 of the arm 21 so as to face the side surface of the workpiece W. Next, the actuator 15 is driven to narrow the distance between the pair of arms 21.

  As the distance between the pair of arms 21 is reduced, the left and right grip plates 22 come into contact with the side surface of the workpiece W as shown in FIG. As the distance between the arms 21 is further reduced, the gripping plate 22 swings upward with respect to the arms 21 by the link bar 35 as shown in FIG. The coil spring 30 urges the grip plate 22 to return downward. Therefore, a force for gripping the workpiece W from the side surface is generated on the gripping plate 22. When the workpiece W is gripped and lifted by the link bar 35, the workpiece W rises about 5 mm from the floor surface F. The rising height of the workpiece W is determined by the length of the link bar 35 and the angle at which the link bar 35 can tilt.

  As shown in FIG. 5, when the workpiece W is lifted by the link bar 35 and the gripping device 20 completes the gripping of the workpiece W, the control device 50 detects the distance (grip height H) detected by the distance measuring sensor 40. Is recorded in the memory 50A. The gripping height H at this time is a relative distance (relative height) between the floor surface F (mounting surface) and the arm 21. Thereafter, the hydraulic cylinder 7 is extended to raise the mast 3, and the arm 21 (gripping device 20) is raised from the floor surface F to a predetermined height. The predetermined height at this time may be about 1 meter, for example.

  Next, the clamp lift 1 is caused to travel to the conveyance destination while holding the workpiece W. When arriving at the transport destination, as shown in FIG. 6, the gripping device 20 is moved up and down to a position higher than the height of the placement surface f on which the work W such as a floor or a shelf is placed. And the clamp lift 1 is advanced and the workpiece | work W is located above the mounting surface f. Next, when the hydraulic cylinder 7 is driven and the gripping device 20 is lowered, the arm 21 and the workpiece W approach the placement surface f. Here, the distance sensor 40 detects the distance (arm height h) between the lower end of the arm 21 and the placement surface f. In the present embodiment, the arm height h starts to be measured by the distance measuring sensor 40 as the arm 21 starts to descend. Then, the control device 50 compares the gripping height H of the arm 21 when gripping the workpiece W recorded in the memory 50A with the arm height h of the arm 21 being lowered.

  The distance measuring sensor 40 continues to detect the arm height h while the arm 21 is being lowered. The control device 50 continues the comparison until the gripping height H and the descending arm height h become the same. When the gripping height H and the arm height h have the same value, the control device 50 stops driving the hydraulic cylinder 7 and stops the gripping device 20 from descending. Then, the workpiece W is lifted by the link bar 35 when it is gripped with respect to the placement surface f, and has a height of about 5 mm. Then, the actuator 15 is driven to gently widen the left and right spacing of the arm 21. As the distance between the pair of arms 21 increases, the link bar 35 gradually tilts in the horizontal direction due to the load of the workpiece W. As the link bar 35 tilts, the grip plate 22 moves down with respect to the arm 21. When the grip plate 22 is lowered, the workpiece W gradually approaches the placement surface f.

  Further, the distance between the arms 21 is increased and tilted until the link bar 35 comes into contact with the stopper 21C. Then, the workpiece W is in a state of landing on the placement surface f. Then, the distance between the arms 21 is further increased by the actuator 15. Then, the workpiece | work W can be mounted on the mounting surface f of a conveyance destination, and conveyance is completed.

According to the present embodiment, the following effects can be obtained.
(1) The grip height H when gripping the workpiece W is stored in the memory 50A, and compared with the arm height h detected by the distance measuring sensor 40 when the workpiece W is placed on the placement surface f of the transport destination. By doing so, it is possible to grasp the height position of the arm 21 where the workpiece W lands on the placement surface f.
(2) The control device 50 compares the gripping height H and the arm height h, and stops the lowering of the arm 21 when the values are the same, so the workpiece W is damaged by the collision with the mounting surface f. It is possible to smoothly land on the mounting surface f without any problem.

(3) Since the distance measuring sensor 40 detects the distance (arm height h) between the arm 21 and the placement surface f, the floor surface F that grips the workpiece W and the height of the placement surface f on which the workpiece W is placed. Even if the heights are different, the workpiece W can be smoothly landed according to the height of the placement surface f. And it is not necessary to set the height of the floor surface F, the mounting surface f, etc. in the control apparatus 50 beforehand. In addition, it is not necessary to change the setting according to the height change of the placement surface f.
(4) One distance measuring sensor 40 may be provided in the gripping device 20, and an increase in the number of parts and cost of the gripping device 20 can be minimized.

(5) Since the arm height h is detected by the distance measuring sensor 40 and the lowering of the arm 21 is stopped at the position where the workpiece W comes into contact with the placement surface f, even a beginner who is unfamiliar with the work may damage the workpiece W. Can be transported without any problems.
(6) Since the arm height h is detected by the distance measuring sensor 40, it is possible to place the workpiece W without damaging the workpiece W even in a situation where the operator cannot visually confirm the placing surface f and the lowered state of the workpiece W. Moreover, since it is not necessary to confirm visually, an operator's burden can be reduced.

(7) Since the gripping device 20 uses the gripping plate 22 and the link bar 35, the gripping device 20 can lift the workpiece W at the same time as it grips it. Further, when placing the workpiece W, the workpiece W can be lowered slowly, and smoother placement is possible.

(Second Embodiment)
Hereinafter, the gripping device 60 according to the second embodiment will be described.
The gripping device 60 adds a distance measuring sensor 40 to the gripping device 20 of the first embodiment. As shown in FIG. 7, the distance measuring sensor 40 is provided on each of the pair of arms 21. The distance measuring sensor 40 uses the same thing on the left and right, and the mounting position on the arm 21 is also the same. The two distance measuring sensors 40 are both connected to the control device 50.

  Next, cargo handling work by the gripping device 60 of this embodiment will be described. Here, a case will be described in which the workpiece W placed on the floor surface F (mounting surface) shown in FIG. 7 is placed near the end of the placement surface f of the shelf T shown in FIG.

  First, the operator operates the clamp lift 1 to grip and lift the workpiece W with the gripping device 60 as shown in FIG. The procedure for gripping is the same as in the first embodiment. The workpiece W is gripped by the pair of gripping plates 22 and slightly lifted from the floor surface F. Then, the distance (grip height HR, HL) from the pair of arms 21 to the floor surface F is stored in the memory 50A by the distance measuring sensor 40 at this time.

  Then, as shown in FIG. 8, the work W is transported to the shelf T as the transport destination. The operator operates the clamp lift 1 to raise and lower the gripping device 60 higher than the placement surface f of the shelf T, and position the workpiece W above the designated placement location of the shelf T. In the present embodiment, the gripping device 60 places the workpiece W on the end of the shelf T. When placing on the end of the shelf T, one (right side) arm 21 is positioned above the placement surface f as shown in FIG. However, the other (left side) arm 21 is located on the side of the end of the shelf T. Therefore, the distance measuring sensor 40 provided on the other (left) arm 21 cannot detect the placement surface f of the shelf T and detects the distance to the floor surface F (arm height hL).

  The control device 50 notifies the operator when the arm heights hR and hL detected by the pair of left and right distance measuring sensors 40 are different. Then, the worker visually confirms whether the mounting surface f and other abnormalities are present. When the placement is continued when it is not abnormal, the operator selects which detection value of the pair of left and right distance measuring sensors 40 is to be used. In this embodiment, it is determined to use a value detected by one (right side) distance measuring sensor 40.

  The control device 50 starts to lower the arm 21 using the detection value (arm height hR) of the distance measuring sensor 40 selected by the operator. Then, the control device 50 compares the gripping heights HR and HL stored in the memory 50A with the arm height hR, and when the arm height hR becomes the same as the gripping heights HR and HL, Stop descent. Then, similarly to the first embodiment, the arm 21 is expanded by the actuator 15 and the link bar 35 is tilted downward. As the link bar 35 tilts, the grip plate 22 descends, and the workpiece W gently lands on the placement surface f of the shelf T. Further, the arm 21 is expanded and the transfer of the workpiece W is completed.

In this embodiment, in addition to the effects (1) to (7) of the first embodiment, the following effects are obtained.
(8) Since the distance measuring sensors 40 are provided on the pair of arms 21, the height of the arms 21 can be detected on both sides.
(9) Since the control device 50 notifies the operator when the detection values by the left and right distance measuring sensors 40 are large, if the placement surface f is abnormal, the control device 50 erroneously continues the placement work. There is no risk of damaging the workpiece W.

(10) Even when the detection values of the left and right distance measuring sensors 40 are greatly different, the operator can select one of the detection values and continue the mounting operation, so the end of the mounting surface f of the shelf T It is possible to effectively utilize the place for placing such as the end of a section or pallet.

The present invention is not limited to the above embodiment, and modifications of the present invention will be described below.
In the above embodiment, the gripping height H and the arm height h are compared, and when the values are the same, the lowering of the arm 21 is stopped, but the difference between the gripping height H and the arm height h is a predetermined value. The lowering of the arm 21 may be stopped when the following occurs. Further, the lowering speed may be decreased as the difference becomes smaller.

The distance measuring sensor 40 is provided at the lower front end of the arm 21, but may be any position that can measure the distance to the placement surface f even on the side surface or the rear side of the arm 21.
The distance measuring sensor 40 is not limited to an optical type. When the arm 21 is provided at the lower end, various sensors such as a proximity sensor can be used.

The distance measuring sensor 40 may be provided on the holding plate 22 as shown in FIG. By providing the grip plate 22, it is possible to grasp the height at which the work W is lifted by the link bar 35 when gripping the work W.
The gripping devices 20 and 60 may not include the gripping plate 22. The workpiece W may be directly gripped by the arm 21.

○ The height of the floor or shelf is registered in advance in the control device 50, and it is determined that there is an obstacle such as an obstacle on the mounting surface when the detection value of the distance measuring sensor 40 is significantly different from the registered data. May be.
The arm 21 may be further lowered by the vertical movement amount in the vertical direction in which the work W is swung upward by the link bar 35. In this case, by further lowering the lifting amount by the link bar 35 from the gripping height H, the gripping can be released after the work W is landed on the placement surface f.

In the second embodiment, two distance measuring sensors 40 are provided, but three or more distance measuring sensors 40 may be provided. Further, the inclination of the mounting surface may be grasped by a plurality of distance measuring sensors 40.
In the second embodiment, when gripping the workpiece W, the operator is notified even when the grip heights HR and HL are different, and if it is not abnormal, either value can be selected and stored in the memory 50A. good.

In the first embodiment and the second embodiment, the distance measuring sensor 40 detects the distance from the arm 21 to the floor surface F at the completion of gripping and stores it as the gripping height. However, the present invention is not limited to this. A predetermined distance from the reference height of the arm 21 to the floor F can be stored in the memory 50A, and the relative height of the arm when gripping is completed can be used. The grip height may be obtained by calculating whether the arm 21 is lowered from the reference height of the arm 21 or the amount of lowering.

The grip plate 22 is not limited to support by the link bar 35 and the pin 23. An inclined long hole may be provided in the arm 21 and the pin 23 on the grip plate 22 side may be inserted. Even if a long hole is used, the gripping plate 22 can be swung up and down with respect to the arm 21 and can be separated from each other.
The gripping devices 20 and 60 of the present invention are not limited to forklifts, but may be applied to hand lifts, stackers cranes in automatic warehouses, and the like.

DESCRIPTION OF SYMBOLS 1 Clamp lift 3 Mast 7 Hydraulic cylinder 10 Bracket 15 Actuator 20 Gripping device 21 Arm 21A Flange part 21B Protrusion part 21C Stopper 22 Grasping plate 22A Flange part 22B Protrusion part 23 Pin 30 Coil spring 35 Link bar 40 Distance sensor 50 Control device 50A Memory 60 Grasping device F Floor surface f Placement surface T Shelf W Workpiece

Claims (6)

An arm for gripping the workpiece;
Arm lifting means for lifting and lowering the arm;
Arm height detecting means for detecting a relative height of the arm with respect to a mounting surface on which the workpiece is mounted;
A grip height storage means for storing a grip height obtained from a relative height of the arm detected by the arm height detection means when gripping the work placed on the placement surface;
A gripping apparatus comprising: a comparison means for comparing a grip height stored in the grip height storage means with an arm height detected by the arm height detection means.   The gripping device according to claim 1, wherein the gripping device uses the relative height of the arm from the placement surface detected when the workpiece is gripped as the gripping height.   The gripping device compares the grip height stored in the grip height storage means with the arm height detected by the arm height detection means when the arm is lowered by the arm lifting / lowering means. 3. The gripping apparatus according to claim 1, further comprising a control unit that stops the lowering of the arm when it is determined that the grip height is equal to the arm height. The arms are a pair of arms,
The arm includes a pair of gripping plates that come into contact with the workpiece,
The grip plate is connected to and supported by the arm, the grip plate is swung upward when the grip plate is close to the arm, and the grip plate is moved downward when the grip plate is separated from the arm. The gripping device according to any one of claims 1 to 3, further comprising a link mechanism that swings. The arm height detection means is provided at the lower end of the arm,
5. The gripping apparatus according to claim 4, wherein the arm elevating means further lowers the arm by a vertical movement amount in which the gripping plate swings upward with respect to the arm by the link mechanism.   The gripping device according to claim 4, wherein the arm height detection means is provided at a lower end of the gripping plate.

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