JP6154717B2 - Industrial robot shock absorber - Google Patents

Description

  The present invention is attached between the tip of a robot arm and a tool (tool, hand, processing head, etc.). For example, when a tool collides with a workpiece or the like during teaching of welding work, the robot absorbs the impact and simultaneously the robot The present invention relates to a shock absorber for an industrial robot capable of stopping the operation of an arm.

  For example, in a welding robot, a machining head (welding head) is attached to the tip of a robot arm, and welding is performed while controlling the machining head in various positions and postures. Prior to actual welding, teaching is performed to cause the robot to learn the operation, and at that time, the machining head (tool) may be hit against a workpiece or the like. When the machining head is hit, an overload acts between the machining head and the robot arm, which may damage the machining head or the robot arm.

  Therefore, normally, when an overload exceeding a predetermined level is applied between the robot arm tip and the machining head due to a collision or the like, the impact of the robot arm and the machining head is absorbed and the robot operation is stopped at the same time. A shock absorber is attached.

  Conventionally, for example, an overload detection device (overload detector) described in Patent Document 1 is known as a shock absorber that performs such a function. This overload detection device is a collision sensor that operates with air pressure. Briefly speaking, the tool is held with high rigidity by the air pressure of the air chamber, and when an overload occurs, the tool is instantaneously discharged to discharge the air pressure. It is free to protect and simultaneously send a stop signal to the robot controller to stop the robot arm.

  Below, with reference to FIGS. 3-7, the structure and effect | action of the overload detection apparatus described in patent document 1 are demonstrated.

  3 is an external perspective view of the overload detection device, FIG. 4 is a cross-sectional view showing a state before operation, FIG. 5 is a plan view with some parts removed, and FIG. 6 is a cross-sectional view showing the state during operation, FIG. 7 is an enlarged cross-sectional view of the main part.

  As shown in FIG. 3, the overload detection device 110 described in Patent Document 1 is attached between a mounting face plate 102 at the tip of the robot arm 104 and a tool 106 (such as a gripper or a welding head).

  A pressurized fluid (compressed air) is supplied to the overload detection device 110 through the hose 107, and normally, the overload detection device 110 rigidly couples the mounting face plate 102 and the tool 106. When the tool 106 collides with a workpiece or the like and an overload is generated between the mounting face plate 102 and the tool 106, the overload detection device 110 releases the rigid coupling, Relative motion is generated between the robot arm 104 and the mounting face plate 102 to minimize damage to the tool 106 and the robot arm 104. At the same time, the overload detection device 110 sends an operation stop signal for the robot arm 104 to the robot controller through the cable 108 to stop the robot arm 104.

Overload detection device 110 senses overloads (overloads) that occur in multiple directions due to forces such as compression load FZ, rotational torque FR, chipping moment FT, and horizontal load FL, and simultaneously yields in the same direction Can be done.
As shown in FIG. 4, the overload detection device 110 includes a housing 111 having a ring-shaped end wall 112 and a cylindrical peripheral wall 113, and an opening on the opposite side of the end wall 112 of the housing 111 to block the housing 111. An end face plate 115 that forms an air chamber 114 therein and a housing 111 that is housed in the air chamber 114 and air pressure is introduced into the air chamber 114, thereby closely contacting the sealing surface 117 of the end wall 112 of the housing 111. A sealing plate 116 that keeps the inside of the air chamber 114 in a sealed state, a stem 118 that is coupled to the sealing plate 116 and protrudes to the outside from the opening of the end wall 112 of the housing 111, and a fixture 126 on the stem 118. The mounting bracket 125 and the stem 118 are arranged on the outer periphery of the stem 118, and the opening of the end wall 112 of the housing 111 and the A breathable elastic member 127 that prevents entry of dust and the like into the air chamber 114 through the gap without hindering air escape from the gap with the gap 118, and a conical recess 120 formed in the sealing plate 116. When the housing 111 is screwed into the end wall 112 of the housing 111 and the hemispherical tip is inserted into the conical recess 120 and the housing 111 is rotated or displaced laterally with respect to the sealing plate 116. When the hemispherical tip rides on the slope of the conical recess 120, the screw 119 that releases the sealing plate 116 from the sealing surface 117 of the housing 111 and the air pressure in the air chamber 114 are reduced below a predetermined level. And a sensing sensor 103 for sending an operation stop signal of the robot arm 104 to a robot controller (not shown).

  As shown in FIG. 5, two screws 119 and conical recesses 120 are provided at a distance of about 180 degrees in the circumferential direction. In addition, a spring 130 is interposed between the end face plate 115 and the stem 118 to urge the sealing plate 116 in a direction in which the sealing plate 116 is pressed against the sealing surface 117.

  Then, as shown in FIG. 3, the overload detector 110 is interposed between the robot arm 104 and the tool 106 by fixing the mounting bracket 125 to the mounting face plate 102 and fixing the end face plate 115 to the tool 106. Has been.

  The overload detection device 110 operates as follows.

  Normally, a predetermined air pressure is introduced into the air chamber 114, so that the sealing plate 116 is in close contact with the sealing surface 117, and the air pressure in the air chamber 114 causes the sealing plate 116 to move to the housing 111. It is pressed with a preload. As a result, the housing 111 integrated with the end face plate 115 and the sealing plate 116 integrated with the mounting bracket 125 are in a rigid connection state.

  While teaching is being performed in this state, when the tool 106 hits a workpiece or the like and a moment-type overload state occurs between the tool 106 and the robot arm 104, as shown in FIGS. The housing 111 tilts with respect to the stem 118, and a gap is generated between the sealing surface 117 of the housing 111 and the sealing plate 116 due to the tilt, and the air in the air chamber 114 escapes to the atmosphere through the gap. When an overload state of torque type or horizontal load type occurs, the hemispherical tip of the screw 119 rides on the slope of the conical recess 120 due to the action of torque or horizontal load, and accordingly the housing 111 A gap is generated between the sealing surface 117 and the sealing plate 116, and the air in the air chamber 114 escapes to the atmosphere through the gap.

  Thereby, the rigid coupling state of the housing 111 and the sealing plate 116 is released, and the end face plate 115 coupled to the housing 111 and the mounting bracket 125 coupled to the sealing plate 116 can freely move, and the robot The relative movement between the arm 104 and the tool 106 is allowed, and the impact caused by the collision is absorbed. At the same time, the sensing sensor 103 senses the reduced pressure in the air chamber 114 and sends a robot arm stop signal to the robot controller, thereby stopping the robot arm.

Japanese Patent Laid-Open No. 5-4190

  By the way, in the conventional example described in Patent Document 1, since only the overload detection device 110 is incorporated in the robot as a shock absorber, an error occurs immediately after the tool 106 hits a workpiece or the like during teaching. Was forcibly stopped, and errors occurred frequently.

  In consideration of the above circumstances, the present invention is an industrial robot that can avoid frequent errors even when a tool hits a workpiece or the like during teaching, for example, and can facilitate teaching work. An object is to provide a shock absorber.

  In order to solve the above problem, the invention of claim 1 is characterized in that the robot arm and the tool attached to the tip of the robot arm are always rigidly coupled to the tip of the robot arm and the tool. When an overload due to impact acts between the tip of the robot arm and the tool, the rigid arm is released to absorb the impact and simultaneously output a signal to stop the operation of the robot arm. In a shock absorber for an industrial robot provided with an overload detection device, the tip of the robot arm and the tool are provided between the tip of the robot arm and the tool, separately from the overload detection device. Are always rigidly connected, and the overload detection device is activated when an overload is applied between the tip of the robot arm and the tool. Wherein the auxiliary shock-absorbing device which absorbs the shock to release said rigid connection with a small overload than overload is provided.

  The invention of claim 2 is the shock absorber for the industrial robot according to claim 1, wherein the auxiliary impact mitigating device is engaged with a first member engaged with a tip end side of the robot arm, and the tool side. A second member engaged with the first member, a piston provided on one of the first member and the second member, and a second member provided on the other of the first member and the second member, and sliding the piston And a cylinder that forms an air damper together with the piston by freely accommodating and forming an air pressure chamber with the piston, and an air pressure of a certain level or more introduced into the air pressure chamber of the cylinder The piston is pressed against the sliding limit position with a predetermined preload, so that the first member and the second member are always rigidly coupled to each other by the preload, and between the first member and the second member. Over the preload When heavy acts, said piston is characterized in that to absorb the impact by being displaced in a cylinder.

  The invention of claim 3 is the shock absorber for the industrial robot according to claim 2, wherein the piston is formed in a ring shape, the cylinder is formed as an annular recess, and the inside of the cylinder formed by the annular recess is provided. The air damper is configured by the ring-shaped piston being slidably fitted.

  The invention of claim 4 is the shock absorber for the industrial robot according to claim 3, wherein the piston inner peripheral sliding surface and the piston outer peripheral sliding surface which are sliding surfaces of the piston and the cylinder, An elastic O-ring that seals a minute gap secured between the sliding surfaces of the piston and the cylinder is loaded.

  According to the first aspect of the present invention, the auxiliary impact mitigation device that operates with an overload smaller than the overload detection device is provided separately from the overload detection device that stops the robot when an overload due to an impact is applied. Therefore, it is possible to avoid a situation where the robot is frequently forcibly stopped at each small collision, and it is possible to easily perform smooth teaching while preventing damage due to impact.

  According to the invention of claim 2, since the auxiliary impact mitigating device includes the air damper, it is possible to set the operating point (limit point) of the auxiliary impact mitigating device when an overload is easily applied by the introduced air pressure.

  According to the invention of claim 3, since the air damper is configured by the ring-like piston being slidably fitted inside the cylinder formed of the annular recess, the shock absorption can be performed in a balanced manner.

  According to the invention of claim 4, the piston can be tilted with respect to the cylinder by the minute gap between the sliding surfaces of the piston and the cylinder, and the displacement in the tilting direction when the impact is applied is determined by the elasticity of the O-ring. Can be absorbed by sex.

It is the front view which made a part the cross section which shows the front-end | tip part structure of the welding robot as embodiment of this invention. It is an expanded sectional view of the principal part of FIG. It is an external appearance perspective view of the overload detection apparatus which is the conventional buffer device. It is sectional drawing which shows the state before the operation | movement of the same overload detection apparatus. It is the top view which removed a part of parts of the overload detection device. It is sectional drawing which shows the state at the time of the action | operation of the same overload detection apparatus. It is an expanded sectional view of the principal part of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a front view, partly in section, showing the configuration of the tip of a welding robot as an embodiment, and FIG. 2 is an enlarged sectional view of the main part of FIG.

  As shown in FIG. 1, this welding robot (industrial robot) A has an attachment face plate 3 for attaching a tool to the tip of a robot arm 1, and an overload detection device 10 and an attachment face plate 3 are attached to the attachment face plate 3. A configuration is provided in which a machining head (welding head) 2 as a tool is attached via an auxiliary impact relaxation device 20.

  Here, the auxiliary impact mitigation device 20 is disposed on the mounting face plate 3 side of the robot arm 1 and the overload detection device 10 is disposed on the mounting bracket 4 side of the machining head 2. The mitigation device 20 may be reversed, that is, the overload detection device 10 may be disposed on the mounting face plate 3 side of the robot arm 1, and the auxiliary impact mitigation device 20 may be disposed on the mounting bracket 4 side of the machining head 2.

  Since the overload detection device 10 is equivalent to or similar to the overload detection device 110 described in Patent Document 1 described with reference to FIGS. 3 to 7, a brief description will be given. A housing 11 having a cylindrical peripheral wall 13, an end face plate 15 that forms an air chamber 14 in the housing 11 by closing an opening on the opposite side of the end wall 12 of the housing 11, and is accommodated in the housing 11. When air pressure is introduced into the inner wall 14, the sealing plate 16 is brought into close contact with the sealing surface 17 of the end wall 12 of the housing 11, thereby keeping the inside of the air chamber 14 in a hermetically sealed state. The stem 18 that is coupled and protrudes to the outside from the opening of the end wall 12 of the housing 11, and the bracket member 21 that is coupled to the stem 18 by a fixture 56 (of an auxiliary impact mitigation device 20 described later). In the air chamber 14 for dust and the like through the gap without hindering air escape from the gap between the opening of the end wall 12 of the housing 11 and the stem 18. A breathable elastic member 57 that prevents intrusion into the air chamber, and a sensor (not shown) that sends an operation stop signal of the robot arm 3 to a robot controller (not shown) when the air pressure in the air chamber 14 is reduced below a predetermined value. Abbreviation).

  A mounting bracket 4 on the processing head 2 side is coupled to the end face plate 15 of the overload detection device 10. Further, the bracket member 21 fixed to the stem 18 is fixed to the mounting face plate 3 of the robot arm 3.

  The sealing plate 16 has a conical recess (not shown), and a screw (not shown) is screwed into the end wall 12 of the housing 11. The screw has a hemispherical tip, the hemispherical tip is inserted into the conical recess, and when the housing 11 is rotated or displaced laterally with respect to the sealing plate 16, The hemispherical tip of the screw rides on the slope of the conical recess, so that the sealing plate 16 can be released from the sealing surface 17 of the housing 11. In addition, a spring 30 is interposed between the end face plate 15 and the stem 18 to urge the sealing plate 16 in a direction in which the sealing plate 16 is pressed against the sealing surface 17.

  This overload detection device 10 always rigidly couples the tip of the robot arm 1 and the machining head 2, and when an overload due to an impact acts between the tip of the robot arm 1 and the machining head 2, A signal for stopping the operation of the robot arm 1 is output at the same time as the impact is absorbed by releasing the rigid coupling, and the auxiliary impact mitigation device 20 is separated from the overload detection device 10 by the robot arm 1. It is provided between the tip portion and the processing head 2.

  In addition to the overload detection device 10, the auxiliary impact mitigation device 20 always rigidly couples the tip of the robot arm 1 and the machining head 2, and impacts between the tip of the robot arm 1 and the machining head 2. When an overload is applied, the rigid connection is released and the impact is absorbed by an overload smaller than the overload at which the overload detection device 10 operates.

  Specifically, the auxiliary impact mitigation device 20 is engaged with the bracket member 21 as the first member joined to the attachment face plate 3 at the tip of the robot arm 1 and the housing 11 of the overload detection device 10. Two members 22, a ring-shaped piston 27 provided on the second member 22, and an outer peripheral wall 23 of the bracket member 21, which is the first member. The piston 27 is slidably received, and the piston The air pressure chamber 24 is formed between the air cylinder 20 and the cylinder 25 that constitutes the air damper 20 </ b> A together with the piston 27. The cylinder 25 is formed as an annular recess so as to accommodate the ring-shaped piston 27. A stopper 28 for preventing the piston 27 from dropping off is attached to the opening side of the cylinder 25.

  Here, the axis of the overload detection device 10 coincides with the axis of the mounting face plate 3 of the robot arm 1, and the sliding direction of the piston 27 coincides with the axial direction of the overload detection device 10. Further, a minute clearance secured between the sliding surfaces of the piston 27 and the cylinder 25 is sealed to the piston inner peripheral sliding surface S2 and the piston outer peripheral sliding surface S1, which are sliding surfaces of the piston 27 and the cylinder 25. An elastic O-ring 29 is loaded.

  In the auxiliary impact mitigating device 20, the piston 27 is pressed against the sliding limit position (position where the housing 11 is engaged) with a predetermined preload by a predetermined or higher air pressure introduced into the pneumatic chamber 24 of the cylinder 25. Thus, the bracket member 21 as the first member and the second member 22 are always rigidly coupled by preload. When an overload exceeding the preload is applied between the bracket member 21 (first member) and the second member 22, the piston 27 is displaced in the cylinder 25 to absorb the impact. However, the impact is absorbed by releasing the rigid coupling with an overload smaller than the overload at which the overload detection device 10 operates. In FIG. 2, the sliding range of the piston 27 is indicated by L1 and L2.

  Next, the operation will be described.

  In normal times, the second member 22 is pressed against the housing 11 of the overload detection device 10 by introducing a predetermined air pressure into the pneumatic chamber 24 of the auxiliary impact mitigation device 20. Thereby, the bracket member 21 fixed to the robot arm 1 side and the housing 11 fixed to the processing head 2 side are in a rigid coupling state.

  Further, when another air pressure is introduced into the air chamber 14 of the overload detection device 10, the sealing plate 16 joined to the robot arm 1 side is in close contact with the sealing surface 17, and the inside of the air chamber 14 The air pressure presses the sealing plate 16 against the housing 11 with a preload. Thereby, the housing 11 integrated with the end surface plate 15 and the sealing plate 16 integrated with the bracket member 21 are in a rigid coupling state.

  When the machining head 2 hits a workpiece or the like during teaching in this state and an overload is generated between the machining head 2 and the robot arm 1, first, the auxiliary impact mitigating device 20 is activated first. . That is, when the piston 27 slides in the cylinder 25, the impact applied between the bracket member 21 and the second member 22 is absorbed.

  At this time, since the air damper 20A is configured by the ring-shaped piston 27 slidably fitted inside the cylinder 25 formed of an annular recess, shock absorption can be performed in a balanced manner. Further, the piston 27 can be tilted with respect to the cylinder 25 by a minute gap between the sliding surfaces of the piston 27 and the cylinder 25, and the displacement in the tilting direction when an impact is applied is caused by the elasticity of the O-ring 29. Can be absorbed. That is, the displacement due to the impact can be absorbed by tilting the piston 27 when an unbalanced load is applied.

  When an even greater impact is applied, the overload detection device 10 operates as described above, so that the impact is absorbed and at the same time a stop signal for the robot arm 1 is sent to the robot controller. Stops.

  As described above, in the welding robot according to the present embodiment, the overload detection device is separated from the overload detection device 10 that stops the robot when an overload due to an impact is applied between the machining head 2 and the robot arm 1. Since the auxiliary impact mitigation device 20 that operates with an overload smaller than 10 is provided, it is possible to avoid a situation where the robot frequently stops at every small collision, and smooth teaching while preventing damage due to impact. It can be performed.

  In particular, since the auxiliary shock absorbing device 20 includes the air damper 20A, the operating point of the auxiliary shock absorbing device 20 when an overload is easily applied by the introduced air pressure can be changed.

  In the embodiment, the piston 27 is formed on the second member 22 engaged with the machining head 2 side, and the cylinder 25 is formed on the first member (bracket member) 21 engaged with the robot arm 1 side. However, the piston and the cylinder may be formed in reverse. That is, a cylinder may be formed on the second member 22, and a piston may be formed on the first member (bracket member) 21.

1 Robot arm 2 Machining head (tool)
DESCRIPTION OF SYMBOLS 10 Overload detection apparatus 20 Auxiliary impact mitigation apparatus 20A Air damper 21 Bracket member (1st member)
22 Second member 24 Pneumatic chamber 29 O-ring S1 Piston inner peripheral sliding surface S2 Piston outer peripheral sliding surface

Claims (4)

Between the robot arm and the tool attached to the tip of the robot arm,
The robot arm tip and the tool are always rigidly coupled, and when an overload is applied between the robot arm tip and the tool, the impact is released by releasing the rigid coupling. In the shock absorber of an industrial robot provided with an overload detection device that outputs a signal for stopping the operation of the robot arm at the same time,
Apart from the overload detection device between the tip of the robot arm and the tool,
The overload is such that the robot arm tip and the tool are always rigidly coupled, and the overload detector is activated when an overload is applied between the robot arm tip and the tool due to an impact. A shock absorber for an industrial robot, characterized in that an auxiliary impact mitigation device is provided that releases the rigid coupling and absorbs the impact with a smaller overload. The industrial robot shock absorber according to claim 1,
The auxiliary impact mitigation device is
A first member engaged with the tip side of the robot arm;
A second member engaged on the tool side;
A piston provided on one of the first member and the second member;
A cylinder that is provided on the other of the first member and the second member, slidably houses the piston, and forms an air pressure chamber with the piston by forming an air pressure chamber between the piston and the piston. And,
The first member and the second member are always rigidly coupled to each other by the preload by the piston being pressed with a predetermined preload to the sliding limit position by a predetermined air pressure introduced into the pneumatic chamber of the cylinder. In addition, when an overload exceeding the preload acts between the first member and the second member, the industrial robot absorbs the impact by displacing the piston in the cylinder. Shock absorber. The industrial robot shock absorber according to claim 2,
The piston is formed in a ring shape, the cylinder is formed as an annular recess, and the ring damper is slidably fitted into a cylinder made of the annular recess, whereby the air damper is configured. Industrial robot shock absorber. A shock absorber for an industrial robot according to claim 3,
O which has elasticity which seals a minute clearance secured between the sliding surface of the piston and the cylinder on the sliding surface of the piston inner peripheral side and the piston outer peripheral side which is a sliding surface of the piston and the cylinder. A shock absorber for an industrial robot, wherein a ring is loaded.

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