JP6550679B2 - Shock absorber for screw tightening device - Google Patents

Description

  The present invention relates to a shock absorber having an elastic member, and more particularly to a shock absorber for a screw tightening device for tightening a screw member held at the tip of a driver bit on a work member.

  In an automatic assembly line for assembling various devices, a screw clamping device is used to clamp a screw member on a large number of work members of the same structure. The screw tightening device usually includes a motorized driver, a driver bit connected to the motorized driver, and a screw holder connected to the driver bit, and is installed at the tip of the robot arm via a mounting stay. In such a screw tightening device, based on the data of the screw hole position calculated from the design data, the driver bit in which the screw member is vacuum-sucked by the screw holder is moved right above the screw hole provided in the work member. When the screw member is disposed immediately above the screw hole, the screw member is tightened to the work member by rotating the driver bit in the direction around the screw tightening axis while being lowered.

  However, for example, due to the calculated screw hole position data and the dimensional tolerance of the work member, a screw bit is generated between the actual position of the screw hole and the position where the screw bit is placed. The date may not be correct. In such a case, that is, when "lifting" occurs at the screw hole position of the screw member, the driver receives an impact due to an external force on the driver bit generated by the screw member contacting the work member at a position other than the predetermined screw hole position. Bits, screw retainers, robots, work members, etc. may be damaged, which may interrupt the automatic assembly line for repair or replacement.

  Heretofore, as a screw tightening device for avoiding such a disadvantage, as shown in FIG. 3, a structure having a buffer mechanism using a spring (or an air cylinder) between a robot arm and an electric driver is provided. Are known. The screw tightening device having such a configuration can buffer an impact due to an external force on the driver bit caused by the lifting of the screw member. However, since the shapes of the robot arm and the motorized driver differ from manufacturer to manufacturer, it is necessary to install a dedicated buffer mechanism corresponding to each screw tightening device, which causes a problem of cost and time.

  For this reason, in recent years, as disclosed in, for example, Patent Document 1, a driven shaft having a bit receiving hole for inserting a driver bit is provided between a motorized driver and a driver bit, and a bottom portion of the bit receiving hole There has been proposed a screw tightening device having a buffer mechanism having a configuration in which an elastic member is interposed between the bottom surface of the bit. The screw tightening device described in Patent Document 1 does not install a buffer mechanism using a spring or an air cylinder between the robot arm and the electric driver, but arranges an elastic member between the electric driver and the driver bit. Based on the idea of doing so, the buffer mechanism is made compact.

JP 2012-096296 A

  However, since the buffer mechanism described in Patent Document 1 has a structure in which the driver bit itself contacts and supports the elastic member 321, the driver bit 33 is axially moved when an upward external force is applied to the driver bit 33. Therefore, there is a problem in that the driver bit is not stable and the looseness causes so-called looseness. In addition, since the elastic member 321 is disposed in the bit receiving hole provided in the driven shaft 31, the operating force (biasing force) and the degree of deterioration can not be visually confirmed, and adjustment, replacement, etc. It's not easy.

  The present invention has been made based on the above-mentioned circumstances, and is a shock absorber for a screw tightening device, which absorbs an impact due to an external force to a driver bit caused by contact of a screw member with a work member. It is an object of the present invention to provide a shock absorber which can prevent breakage of a driver bit, a screw holder, a robot, a work member, etc. and is compact and easy to handle.

  In order to solve the above-described problems, the present invention provides a shock absorber for a screw tightening device including an electric driver and a driver bit that is rotationally driven by the electric driver, the insertion hole extending in the direction of the rotation axis of the driver bit. And a second member having a sliding portion slidably inserted in the insertion hole along the inner circumferential surface thereof in the insertion hole, the first member and the first member, and An elastic member disposed on at least an outer peripheral surface of the second member among the two members, and a connecting shaft provided coaxially with the rotating shaft and detachably connecting the first member and the electric driver, The first member has a contact portion that contacts the first end portion of the elastic member on the electric driver side, and the second member supports the second end portion of the elastic member on the driver bit side. And grip the driver bit Provided is a shock absorber having a holding hole, wherein the elastic member biases the second member in the direction of separating from the first member between the contact portion and the support portion (Invention 1). .

  The buffer mechanism configured to provide a spring (or air cylinder) between the robot arm and the electric driver needs to be manufactured as a dedicated buffer mechanism corresponding to the shapes of the robot arm and the electric driver, which is expensive and time-consuming. According to this invention (Invention 1), in addition to being able to absorb an impact due to an external force on the driver bit generated by the screw member coming into contact with the work member, it is arranged between the electric driver and the driver bit. As a result, the shock absorber can be made compact, and the cost and time required for manufacturing and installation can be reduced. Further, since the second member having the sliding portion supports the end portion of the elastic member on the driver bit side and holds the driver bit, the driver bit does not loosen even when an external force is applied. Therefore, no mechanical backlash occurs and the screw tightening operation can be performed stably. Furthermore, since the elastic member is disposed on the outer peripheral surface of the second member having at least the sliding portion of the first member and the second member, the operating force (biasing force) and the degree of deterioration can be easily confirmed visually Therefore, adjustment or replacement can be easily performed.

  In the present invention, the screw member is not only a fastener generally called a screw consisting of a screw-cut shaft and a head having a diameter larger than that of the screw, but also a screw, a rivet, a nail, etc. It is a concept including general parts having a circular or polygonal head in a plan view and a rod-shaped shaft portion extended from the center of the head.

  In the said invention (invention 1), it is preferable to provide the detection mechanism which detects the external force with respect to the said driver bit based on the relative moving distance of the said rotating shaft direction of the said 2nd member (invention 2).

  According to this invention (Invention 2), the relative movement distance of the second member in the direction of the rotation axis can be measured by the detection mechanism, so that, for example, by using this measured value as detection data If an external force is applied to the driver bit, the failure may be prevented by stopping the screw tightening device, or the driver bit may be made to follow an actual screw hole by finely adjusting the position of the driver bit. It becomes possible.

  In the above inventions (Inventions 1 and 2), preferably, the contact portion is movably disposed in the rotation axis direction so that the position of the first end of the elastic member can be adjusted. (Invention 3).

  According to this invention (invention 3), by adjusting the position of the first end of the elastic member, the biasing force exerted on the second member by the elastic member can be adjusted, so that what size and material are used It is possible to exert a buffering function also on the workpiece member.

  According to the shock absorber for the screw tightening device of the present invention, in addition to being able to absorb an impact due to an external force on the driver bit caused by the screw member coming into contact with the work member, between the motorized driver and the driver bit By the arrangement configuration, since the shock absorber can be made compact, the cost and time required for manufacturing and installation can be reduced. Further, since the second member having the sliding portion supports the end portion of the elastic member on the driver bit side and holds the driver bit, the driver bit is loosened even when an external force is applied to the driver bit. Therefore, no mechanical backlash occurs and the screw tightening operation can be performed stably. Furthermore, since the elastic member is disposed on the outer peripheral surface of the second member having at least the sliding portion of the first member and the second member, the operating force (biasing force) and the degree of deterioration can be easily confirmed visually Therefore, adjustment or replacement can be easily performed.

Fig.1 (a) is a schematic block diagram which shows the shock absorber for screw clamp apparatuses which concerns on one Embodiment of this invention, FIG.1 (b) is a center longitudinal cross-sectional view of Fig.1 (a). FIG. 2 is a schematic perspective view showing a state in which the electric driver in the shock absorber for a screw tightening device of FIG. 1 (a) is connected. FIG. 3 is a schematic diagram showing a conventional screw tightening device provided with a buffer mechanism.

  Hereinafter, a shock absorber for a screw tightening device according to an embodiment of the present invention will be described with reference to the drawings as appropriate. The embodiments described below are for the purpose of facilitating the understanding of the present invention, and do not limit the present invention at all.

  As shown in FIGS. 1A and 1B, a shock absorber 1 for a screw tightening device according to the present embodiment is disposed between an electric driver and a driver bit that is rotationally driven by the electric driver. The first member 11 in which the insertion hole 111 is bored in the direction of the rotation axis of the bit (hereinafter referred to as the rotation axis X), and the insertion hole 111 can slide in the rotation axis X direction along its inner circumferential surface The second member 12 having the sliding portion 121 inserted therein, the elastic member 13 disposed on at least the outer peripheral surface of the first member 11 and the second member 12, and the rotation axis X are provided coaxially. A connecting shaft 14 for detachably connecting the first member 11 and the electric driver, a detection mechanism 15 for detecting an external force applied to the driver bit, and a fixing member 16 for fixing the first member 11 to the electric driver Prepare mainly.

<First member>
The first member 11 is a substantially cylindrical member, and a cylindrical insertion hole 111 is bored coaxially with the central axis of the first member 11 from one end in the axial direction to the other end. A through hole 113 into which one end of the connecting shaft 14 is inserted is formed at the center of the other end in the axial direction.

  The first member 11 has an abutment portion 112 on its outer peripheral surface that abuts on a first end 131 of the elastic member 13 on the electric driver side. The contact portion 112 is disposed movably in the rotation axis X direction so that the position of the first end 131 of the elastic member 13 can be adjusted. With such a configuration, by adjusting the position of the first end portion 131, the biasing force exerted on the second member 12 by the elastic member 13 can be adjusted. It is possible to exert a buffering function also on the work member.

  Although the specific structure of the contact part 112 is not specifically limited, In this embodiment, the contact part 112 functions as what is called an ajastring. That is, the abutting portion 112 has a ring shape in which a thread groove is cut on the inner peripheral surface, and is screwed into a screw thread formed on the outer peripheral surface of the first member 11, whereby the first member 11. By rotating with respect to the rotation axis X as an axis, the rotation axis X is arranged so as to be movable in the direction of the rotation axis X.

  Further, the first member 11 has a through hole 113 through which the connecting shaft 14 can be inserted, and the first member 11 is connected by inserting the connecting shaft 14 connected to the electric driver into the through hole 113. It is connected to an electric driver via a shaft 14. Various known methods can be adopted as a method of fixing the connecting shaft 14 inserted into the through hole 113 to the first member 11, and for example, a screw type, a coupler type, or the like can be adopted. As a method of connecting the connecting shaft 14 to the electric driver, a conventional method of connecting the driver bit to the electric driver can be adopted. For example, a screw-in type, a coupler type, or the like can be adopted.

<Second member>
The second member 12 includes a cylindrical sliding portion 121 inserted into the insertion hole 111 of the first member 11 so as to be slidable in the direction of the rotation axis X along the inner peripheral surface thereof, and a driver bit of the sliding portion 121 A flange-shaped support portion 122 that supports the second end portion 132 on the driver bit side of the elastic member 13 provided at the end portion on the side, and is drilled in the center of the end portion where the support portion 122 is provided. And a gripping hole 123 capable of gripping the driver bit. The sliding portion 121 of the second member 12 is slightly smaller in diameter than the insertion hole 111 of the first member 11, and the sliding portion 121 can smoothly reciprocate with respect to the insertion hole 111 of the first member 11. It is configured to be able to

  Although the specific configuration of the support portion 122 is not particularly limited, in the present embodiment, the support portion 122 is provided integrally with the sliding portion 121 at the end of the second member 12 on the driver bit side. Thus, by providing the support part 122 integrally with the sliding part 121, it is not necessary to add a special part in order to comprise the 2nd member 12, and it can be set as the simple structure with few number of parts. It becomes possible.

  Various known methods can be adopted as a method of holding the driver bit inserted into the holding hole 123 on the second member 12, and for example, a screw type, a coupler type, or the like can be adopted.

  Here, the driver bit held by the holding hole 123 of the second member 12 is more securely fixed to the second member by the other holding mechanism 17 disposed on the driver bit side of the second member 12 Can be configured to

  The specific configuration of the gripping mechanism 17 is not particularly limited, but in the present embodiment, the gripping mechanism 17 has a so-called collet-like structure. Compared with a mechanical chuck in which the collet clamps and fixes the object with a claw such as a scroll chuck, for example, the pressure applied to the object may be smaller, so the object can be strongly fixed while the load on the object is small. It has the advantage of

  The gripping mechanism 17 has a through hole 171 through which the driver bit can be inserted, and a plurality of grooves formed radially from the center of the through hole 171, and presses its outer peripheral surface toward the axial center of the rotation axis X The driver bit inserted through the through-hole 171 is gripped by being elastically displaced. A conventional method can be employed as a method of pressing the outer peripheral surface of the gripping mechanism 17 for elastic displacement, and for example, a flat collet, a pyramidal collet, or the like can be employed.

  Further, the second member 12 has a through hole 124 through which the connecting shaft 14 on the driver bit side can be slidably inserted. By forming the through hole 124 so as to be able to be inserted by sliding on the connecting shaft 14 on the driver bit side, movement of the second member 12 in the rotation axis X direction is hindered by the connecting shaft 14 on the driver bit side. It becomes possible to avoid.

<Elastic member>
The elastic member 13 absorbs external force applied to the driver bit. The elastic member 13 has a diameter larger than at least the sliding portion 121 of the second member 12, and is disposed on the outer peripheral surface of the sliding portion 121. With such a configuration, it is possible to appropriately absorb the external force applied to the driver bit and to easily check the biasing force and the degree of deterioration visually.

  The specific configuration of the elastic member 13 is not particularly limited, but in the present embodiment, the elastic member 13 is a coil spring having a diameter larger than that of the first member 11. The elastic member 13 is disposed on the outer peripheral surfaces of the first member 11 and the second member 12, and thereby the second member 12 is separated from the first member 11 between the contact portion 112 and the support portion 122. Energize. As described above, the elastic member 13 is disposed not only on the outer peripheral surface of the second member 12 but also on the outer peripheral surface of the first member 11, so that the contact portion 112 of the first member 11 is moved to the first of the elastic member 13. It is possible to arrange the end 131 so that the position of the end 131 can be adjusted. Various known members can be used as the elastic member 13, but a coil spring can be particularly preferably used.

  A cylindrical member 18 is provided on the outer periphery of the elastic member 13 so as to move with the movement of the second member 12 in the rotation axis X direction. The specific configuration of the cylindrical member 18 is such that the detection mechanism 15 described later can measure the relative movement distance of the second member 12 in the direction of the rotation axis X, and moves as the second member 12 moves in the direction of the rotation axis X. If it is comprised so that it may do, it will not specifically limit. The material of the cylindrical member 18 is not particularly limited as long as it does not prevent the movement of the second member 12 in the rotational axis X direction, but metal is preferably used from the viewpoint of easiness of detection by the detection mechanism 15.

<Connection axis>
The connecting shaft 14 removably connects the first member 11 and the electric driver. The connecting shaft 14 is provided coaxially with the rotation axis X, the rear end portion on the electric driver side has the same shape as the bottom portion of the driver bit, and the tip portion on the driver bit side is a through hole of the first member 11. It has a shape engageable with 113. With such a configuration, the first member 11 and the electric driver are firmly connected, so that the rotational drive of the electric driver can be directly transmitted to the shock absorber 1.

  The method of fixing the connecting shaft 14 to the first member 11 and the method of connecting the connecting shaft 14 to the electric driver are as described above. Various known materials can be adopted as the material of the connecting shaft 14, but from the viewpoint of wear resistance and strength, chromium-molybdenum high steels similar to driver bits, cemented carbide metals such as carbon steel and chromium steel, etc. It can be adopted suitably.

<Detection mechanism>
Detection mechanism 15, by measuring the moving distance of the rotation axis X direction of the cylindrical member 18 that is provided on the outer periphery of the elastic member 13, detected as the data detect the relative moving distance of the rotation axis X direction of the second member 12 It is The movement distance may be measured by detecting that the end of the cylindrical member 18 has moved to a predetermined position, or by measuring the actual movement distance of the cylindrical member 18 at a predetermined position. It may be Detection data detected by the detection mechanism 15 is output to a control mechanism (not shown). When this detection data exceeds a predetermined value , the control mechanism is caused by a deviation between the position where the driver bit places the screw member and the actual screw hole position, that is, the screw member. If the screw bit position of the screw is “lifted” , it is determined that an external force exceeding the specified level is applied to the driver bit, and the screw tightening device is stopped to prevent malfunction or to finely adjust the driver bit position. can or to follow the actual screw holes a driver bit by adjusting. In the present embodiment, the detection mechanism 15 is provided outside the fixing member 16 described later. However, as long as the movement distance of the cylindrical member 18 in the direction of the rotation axis X can be measured, the mounting position thereof is It is not particularly limited.

<Fixing member>
The fixing member 16 is for fixing the shock absorber 1 to the electric driver. Since the electric driver and the shock absorber 1 are more firmly connected by using the fixing member 16, the driver bit is prevented from shaking due to the rotation of the electric driver due to the driver bit not being directly connected to the electric driver. Is possible.

  The fixing member 16 includes a substantially cylindrical housing portion 161, an opening portion 162 provided on the side surface of the housing portion 161, a bearing 163 disposed on the inner peripheral side of the housing portion 161, and electric power of the housing portion 161. And an attachment portion 164 attached to the end portion on the driver side. By providing the opening portion 162 on the side surface of the housing portion 161 in this manner, it becomes possible to easily carry out the attachment / detachment operation of the connecting shaft 14 to the electric driver, and tightening torque by turning the torque adjustment knob of the electric driver. It is possible to adjust the The size of the opening of the opening 162 is not particularly limited as long as the size of the opening 162 is sufficient for attaching and detaching the connecting shaft 14 to the electric driver and adjusting the tightening torque of the electric driver.

  The bearing 163 is composed of a first bearing 1631 disposed on the electric driver side and a second bearing 1632 disposed on the driver bit side, and the fixing member 16 includes the first bearing 1631 and the second bearing 1632. The 1st member 11 is rotatably supported via this. Thus, by providing the two bearings at a distance, the first member 11 can be more stably supported by the fixing member 16, and the shake of the driver bit accompanying the rotation of the electric driver can be avoided. It becomes possible.

  The mounting portion 164 integrally connects the shock absorber 1 and the electric driver to a robot arm (not shown). The shape of the mounting portion 164 is not particularly limited as long as the motor-driven driver can be connected to the robot arm, and various known ones can be adopted. In addition, the electric driver is configured by configuring the mounting portion for connecting the motorized dry to the robot arm, which is conventionally used independently as the mounting stay, as the mounting portion 164 integrated with the fixing member 16 of the shock absorber 1. It is possible to reduce the time required for the operation of connecting to the robot arm.

  2 shows a state in which the shock absorber 1 of the present embodiment is connected to the electric driver, that is, the first member 11 is connected to the electric driver via the connecting shaft 14, and the fixing member 16 electrically connects the first member 11 It is a typical perspective view which shows the state fixed to the driver. In FIG. 2, the driver bit is shown inserted through a screw holder for vacuum suction of the screw member.

  The embodiments described above are described to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in each of the above embodiments is intended to include all design changes and equivalents that fall within the technical scope of the present invention.

  A shock absorber for a screw tightening device according to the present invention is a shock absorber for a screw tightening device, and absorbs an impact caused by an external force with respect to the driver bit generated when the screw member comes into contact with a work member, Since the screw holder, the robot, the work member and the like can be prevented from being damaged, and the compactness and easy handling, its industrial applicability is extremely large.

DESCRIPTION OF SYMBOLS 1 Shock absorber 11 1st member 111 Insertion hole 112 Contact part 113 Through-hole 12 2nd member 121 Sliding part 122 Support part 123 Gripping hole 124 Through-hole 13 Elastic member 131 1st end part 132 2nd end part 14 Connection shaft DESCRIPTION OF SYMBOLS 15 Detection mechanism 16 Fixed member 161 Housing part 162 Opening part 163 Bearing 1631 1st bearing 1632 2nd bearing 164 Attachment part 17 Grip mechanism 171 Through-hole 18 Cylindrical member

Claims (2)

A shock absorber for a screw tightening device comprising an electric driver and a driver bit rotated by the electric driver,
A first member in which an insertion hole is bored in a rotational axis direction of the driver bit;
A second member having a sliding portion inserted into the insertion hole so as to be slidable in the direction of the rotation axis along the inner peripheral surface thereof;
An elastic member disposed on an outer peripheral surface of at least the second member of the first member and the second member;
A connecting shaft provided coaxially with the rotating shaft and removably connecting the first member and the electric driver ;
A cylindrical member provided so as to move with the movement of the second member in the direction of the rotation axis;
A detection mechanism that detects a relative movement distance of the second member in the rotation axis direction as detection data by measuring a movement distance of the cylindrical member in the rotation axis direction ;
The first member has an abutting portion that abuts on a first end of the elastic member on the electric driver side.
The second member has a support portion that supports the second end portion of the elastic member on the driver bit side, and a gripping hole capable of gripping the driver bit,
The shock absorber urges the second member in a direction away from the first member between the contact portion and the support portion. The shock absorber according to claim 1, wherein the abutting portion is disposed so as to be movable in the direction of the rotation axis so that the position of the first end portion of the elastic member can be adjusted.

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