EP2703099B1

EP2703099B1 - Holder for a joining device

Info

Publication number: EP2703099B1
Application number: EP13182119.1A
Authority: EP
Inventors: Michael Schneider; Alexander Pohl
Original assignee: Newfrey LLC
Current assignee: Newfrey LLC
Priority date: 2012-08-30
Filing date: 2013-08-29
Publication date: 2018-08-22
Anticipated expiration: 2033-08-29
Also published as: CN103658494A; DE102012108031A1; JP2014046365A; EP2703099A1; KR20140029221A; TW201429578A

Description

The invention relates to a holder for a joining device having a first arm and having a second arm that is connected by a swivel joint to the first arm such that it can rotate about an axis and that forms a C-shaped frame with the first arm in a predefined operating position in which the two arms are braced rigidly on one another, wherein the free end of the first arm has a receptacle for a joining device and the free end of the second arm has a receptacle for a mating tool cooperating with the joining device.
Holders of the specified type are used to mount joining devices for producing fastened joints, for example rivet joints and self-piercing rivet joints. Such joining devices have a punch equipped with a drive and also have a mating tool, e.g. in the form of a die. The punch and die are held coaxially to one another on the holder and are supported against the reaction forces arising during the joining process. High demands are placed on the coaxial alignment of the punch and die, since the strength and appearance of the fastened joint produced depend on it to a great degree. In the operating position that produces the fastened joint, coaxial alignment of the joining device and mating tool is a must. For bringing the fastening apparatus to the parts to be joined and for moving it away from them, the holder can be placed in a different shape using its swivel joint, by which means the distance between the joining device and the mating tool is increased so that they can be moved past projections or other obstacles in the vicinity of the parts to be joined.
From US 1,404,126 , a riveter is known with a holder of the initially mentioned type. The dies of the riveter are not coaxial in this design, but instead are arranged at an angle to one another. But it is important here, too, for the joining surfaces of the dies to be located exactly opposite one another during the joining process so that uniform deformation of the rivet is ensured.
Known from EP 1,163,963 B1 is a rivet setting machine with an essentially C-shaped frame that has a movable punch at a first end and, at a second end, a die supporting member with a die located thereon. The die supporting member is movably mounted on the frame and can be moved from a first position in which the die is opposite the punch during fastening operations into a second position in which the die is in a location away from the punch and the distance between the die and punch is increased. In this way, additional space is available for inserting larger and more complicated workpieces into the frame opening and removing them therefrom. The die supporting member is supported in a pivoting manner on an axle journal, and on its underside has a positioning guide with which it is brought into the appropriate position for accommodating the punch pressure in the operating position for joining.
Document DE 197 43 277 A1 describes an adjustment aid for a joining device in which two eccentric bushings are located in a receiving bore in an arm of a C-frame to hold a punch tool. The eccentric bushings have the same eccentricity, and are rotated relative to one another with an open-end wrench to adjust the coaxiality or to compensate for alignment errors. The rotational position of the eccentric bushings that has been adjusted can be locked by means of a screw that can be placed in milled openings on the circumference of the eccentric bushings.
A spot welding gun having a holder according to the preamble of claim 1 is disclosed in JP H04 46682 A . The holder comprises a first gun arm inserted between forks of a second gun arm. Both gun arms are connected by a rotation pivot equipment having a hinge pin which penetrates the two forks and the first gun arm and is supported on bearing brackets arranged at its opposite ends. Thrust washers are placed on both sides of each fork and provide sliding surfaces for the rotation of the gun arms. When the thrust washers are worn and a gap arises between the thrust washers and the forks, bolts of pressing means which are arranged at the bearing brackets can be tightened thereby eliminating the gap and preventing a center difference developed between electrodes at the tip parts of the gun arms.
The object of the invention is to create a holder of the initially mentioned type in which a coaxial adjustment of the receptacles for the joining device and the mating tool is easy to carry out and can be achieved economically. In doing so, it is necessary to ensure that the adjusted coaxiality is maintained over the long term and when the arms of the holder are moved.
According to the invention, this object is attained by a holder for a joining device having a first arm and having a second arm that is connected by a swivel joint to the first arm such that it can rotate about an axis and that forms a C-shaped frame with the first arm in an operating position predefined for joining in which the two arms are braced rigidly on one another, wherein the free end of the first arm has a receptacle for a joining device, and the free end of the second arm has a receptacle for a mating tool cooperating with the joining device, wherein the position of the first arm relative to the second arm can be adjusted in the longitudinal direction of the axis by means of a first adjusting device at the swivel joint, and wherein the position of the first arm relative to the second arm can also be adjustable in a direction perpendicular to the axis by means of a second adjusting device at the swivel joint.. Advantageous further developments of the holder are specified below.
As a result of the adjustability of the swivel joint according to the invention, the arms of the holder, which are manufactured separately from one another, can easily be adjusted in one direction at the swivel joint when they are assembled. The requirements for precision of manufacture of the various parts of the holder can thus be less demanding and permit looser manufacturing tolerances. The axial adjustment at the pivot bearing can be carried out with a simple adjusting device and requires only very little additional construction effort.
As a result of this second adjustment option, the position of the tool receptacle of the first arm relative to the tool receptacle of the second arm can be adjusted in two mutually perpendicular spatial directions, so that the receptacles intended for the joining device and mating tool can be adjusted to be very precisely coaxial to one another in the operating position predefined for joining.
In a preferred embodiment of the frame, the first arm has a forked first bearing section with two bearing branches that extend around a second bearing section of the second arm, wherein the swivel joint is located in mutually aligned bores in the bearing branches and the second bearing section. This design allows a simple and robust implementation of the swivel joint and a distribution of the forces to be transmitted by the swivel joint that is symmetrical to the center plane of the frame.
According to the invention, an advantageous design of the swivel joint can have an axle journal that is attached in a bore of the second arm and whose ends extend out of the bearing section of the second arm on both sides, wherein bearings are arranged on the ends of the axle journal to be axially movable, these bearings being attached in the bores of the bearing branches of the first arm and being designed to support the first arm axially and radially on the axle journal. In this design, the axial position of the bearings relative to the axle journal can be adjusted by means of the first adjusting device.
The design according to the invention of the swivel joint can be manufactured economically using simple, standard components, and is simple to assemble. Moreover, it permits an advantageous embodiment of the first adjusting device, which can have adjusting elements at both ends of the axle journal that limit the axial position of the bearings relative to the axle journal in the direction of the relevant end of the axle journal. The adjusting elements can be composed of an adjusting screw with a flange having a contact surface for a bearing, and a locking screw, wherein the two screws are located in threaded bores on the end faces of the axle journal.
According to the invention, the second adjusting device has eccentric bushings, which are rotatably arranged in the bores in the bearing branches, and which accommodate the bearings. Rotating the eccentric bushings in the bores of the bearing branches makes it possible to displace the bearing center inside the bores, and thus to adjust the position of the first arm relative to the axle journal and thus relative to the second arm in the radial direction.
Each of the eccentric bushings preferably has an annular flange located on the outside of the bearing branches that is provided with openings or recesses, and at which the rotational position of the eccentric bushings can be locked by means of a screw engaging in an opening or recess. In this way the eccentric bushings are easily accessible from outside and can be moved in a simple manner.
According to the invention, the bearings are preferably plain bearings with an inner bushing and an outer bushing that are in engagement with one another through congruent spherical sliding surfaces. As a result of this design of the plain bearings, clamping forces and high stresses resulting from deformation of the branches and of the axle journal under high load are avoided. In addition, asymmetrical movement of the bushings of the plain bearings can be compensated. However, the invention is not limited to the use of such bearings, but can also be implemented by means of conical plain bearings or roller bearings that accommodate axial forces.
To accommodate the joining device and the mating tool, the first and second arms can be provided at their free ends with receiving bores whose center axes each lie in a plane intersecting the center axes of the bores at a right angle, and are parallel in the operating position of the arms predefined for joining, and have a minimal distance from one another. The distance must be smaller than the maximum axial and radial adjustability of the pivot bearing in order to ensure that the receiving bores can be brought into a coaxial position with the aid of the adjusting devices.
The invention is explained in detail below with reference to an exemplary embodiment that is shown in the drawings, wherein:

Figure 1: is a perspective view of a frame according to the invention, and
Figure 2: is a cross-section through the swivel joint of the frame from Figure 1.

Figure 1 shows a frame 1 that has a first arm 2 and a second arm 3, which are connected by a swivel joint 4 to one another so as to be able to rotate about an axis A. The first arm 2 has an essentially straight, elongated shape and extends crosswise to the axis A. One end 5 of the arm 2 is forked to form a bearing section in two bearing branches 6, 7, which accommodate bearings of the swivel joint 4 in coaxial bores. The other free end 8 of the arm 2 is provided with a receptacle 9 for a joining device. The receptacle 9 has a cylindrical bore 10, into which a cylindrical section of the joining device can be inserted. The bore 10 has an axis B that lies in the center plane of the arm 2 perpendicular to the axis A. Approximately in the center, on the side facing away from the arm 3, the arm 2 is provided with a bearing lug 11 that serves to connect to an actuating and support device, by means of which the arm 2 can be rotated relative to the arm 3 and can be braced rigidly on the arm 3 in the operating position for joining shown in Figure 1.
The second arm 3 has essentially the shape of a right angle, with the end 12 of one side of the angle forming a bearing section that is connected to the swivel joint 4 and is located between the bearing branches 6, 7. The free end 13 of the other side of the angle forms a receptacle 14 for a mating tool, for example a die 15. In the vicinity of the swivel joint 4, the arm 3 has an attachment point 16 for attaching a handling device, for example the hand of an industrial robot. Also located on the handling device is the actuating and support device for rotating and supporting the first arm 2.
Figure 2 shows the swivel joint 4 and the devices for adjusting it. The swivel joint 4 has an axle journal 20, a center section of which is inserted without play in a bore 21 in the arm 3. For axial positioning, a collar 22 formed on the axle journal 20 rests against one side of the arm 3. On the opposite side of the arm 3, a nut 23 is screwed on a threaded section of the axle journal 20, resting against the arm 3 and holding the collar 22 in contact with the arm 3. Bearings 24, 25 of identical design are located on the two ends of the axle journal 20 projecting from the arm 3. The bearings 24, 25 have an inner bushing 26 and an outer bushing 27 that are in engagement with one another through congruent spherical sliding surfaces. The bearings 24, 25 thus constitute plain bearings that can transmit forces in both the radial and axial directions. The outer bushings 27 of the bearings 24, 25 are arranged in eccentric bushings 28, each of which is located in a bore 29 in the bearing branches 6, 7 of the arm 2. The outer bushings 27 of the bearings 24, 25 are axially positioned in the eccentric bushings 28 by a stop collar 30 and a resilient retaining ring 31.
At their outer ends, the eccentric bushings 28 have an annular flange 32 that is located in an annular recess on the outside of the applicable bearing branch 6, 7. The annular flange 32 is provided with a number of bores 33 arranged at regular intervals from one another for accommodating a stop screw 34 that can be screwed into a threaded bore in the bearing branch 6 or 7.
The adjusting device for adjusting the position of the arm 2 in the axial direction relative to the arm 3 comprises adjusting screws 35, 36, a threaded section 37 of which is screwed into threaded bores located in the end faces of the two ends of the axle journal 20. The adjusting screws 35, 36 have flanges 38, which constitute contact surfaces for the inner bushings 26 on the outsides of the bearings 24, 25. The adjusting screws 35, 36 are secured against loosening by means of locking screws 39 that engage threaded bores in the axle journal 20.
As is evident from Figure 2, the outer bushings 27 of each of the two bearings 24, 25 are supported on the inside in the direction of the arm 3 at the bearing branches 6, 7 by the stop collar 30, the eccentric bushing 28, and the annular flange 32. In the opposite direction the bearings 24, 25 are braced against the flanges 38 of the adjusting screws 36 by their inner bushings 26, which project beyond the end faces of the axle journal 20. If the arm 2 is to be moved to the left in Figure 2 relative to the arm 3, first the left-hand locking screw 39 is loosened before the left-hand adjusting screw 35 is unscrewed by the amount of the adjustment, and then the right-hand locking screw 39 is loosened before the right-hand adjusting screw 36 is screwed deeper into the threaded bore in the axle journal 20 by the corresponding amount. In this process, the right-hand adjusting screw 36 displaces the right-hand bearing 25, and with it the arm 2 and thus the left-hand bearing 24, far enough to the left that its inner bushing 27 once again rests against the left-hand adjusting screw 35. As a result of such a movement, the receptacle 9 of the arm 2 can be adjusted in the X direction relative to the die 15.
To move the position of the arm 2 in the radial direction relative to the arm 3, the stop screws 34 are loosened before the two eccentric bushings 28 are rotated in the same direction in the bores 29 by a specific angle of rotation. The rotation of the eccentric bushings 28 causes a parallel displacement of the axis of the bores 29 relative to the axis of the axle journal 20 in two spatial directions. For the adjustment of the receptacle 9 relative to the die 15 in the Y direction, the displacement in the direction perpendicular to the axis B is relevant. The maximum movement of the receptacle 9 in the Y direction is limited to twice the eccentricity of the eccentric bushings 28.
By means of the eccentric bushings 28, the parallel alignment of the receptacle 9 with the receptacle 14 can also be adjusted by the means that the eccentric bushings are rotated through different angles of rotation or in opposite directions. However, such a motion can also result in a motion in the X direction, which then must be corrected with the aid of the adjusting screws 35, 36.
Depending on the design of the support and actuating device attached to the bearing lug 11, a movement of the arm 2 in the Y direction may also require an adjustment at the support and actuating device so that the operating position of the arm 2 that is predefined for joining is maintained.
As is evident from the foregoing description, the relative positions of the receptacles 9, 14 for the joining device and for the mating tool can be adjusted in the X and Y directions with the aid of the adjusting devices implemented on the swivel joint 4, thereby establishing a precise coaxial alignment of the receptacles 9, 14 with one another. The adjustment can be performed easily at easily accessible locations on the frame 1, and can be secured over the long term by means of stop screws and locking screws.

Claims

Holder for a joining device having a first arm (2) and having a second arm (3) that is connected by a swivel joint (4) to the first arm (2) such that it can rotate about an axis (A) and that forms a C-shaped frame (1) with the first arm (2) in an operating position predefined for joining in which the two arms (2, 3) are braced rigidly on one another, wherein the free end of the first arm (2) has a receptacle (9) for a joining device, and the free end of the second arm (3) has a receptacle (14) for a mating tool cooperating with the joining device, and wherein the position of the first arm (2) relative to the second arm (3) can be adjusted in the longitudinal direction of the axis (A) by means of a first adjusting device at the swivel joint (4), characterized in that the position of the first arm (2) relative to the second arm (3) can be adjusted in a direction perpendicular to the axis (A) by means of a second adjusting device at the swivel joint (4).
Holder according to claim 1, characterized in that the first arm (2) has a forked first bearing section with two bearing branches (6, 7) that extend around a second bearing section of the second arm (3), and in that the swivel joint (4) is located in mutually aligned bores (29) in the bearing branches (6, 7) and a bore (21) in the second bearing section of the second arm (3).
Holder according to claim 2, characterized in that the swivel joint (4) has an axle journal (20) that is attached in the bore (21) of the second bearing section and whose ends extend out of the second bearing section on both sides, and in that bearings (24, 25) are arranged on the ends of the axle journal (20) to be axially movable, these bearings being attached in the bores (29) of the bearing branches (6, 7) of the first arm (2) and being designed to support the first arm (2) axially and radially on the axle journal (20), wherein the axial position of the bearings (24, 25) relative to the axle journal (20) can be adjusted by means of the first adjusting device.
Holder according to claim 3, characterized in that the first adjusting device has adjusting elements at both ends of the axle journal (20) that limit the axial position of the bearings (24, 25) relative to the axle journal (20) in the direction of the relevant end of the axle journal (20).
Holder according to claim 4, characterized in that the adjusting elements have an adjusting screw (35, 36) with a flange (38) having a contact surface for a bearing (24, 25), and have a locking screw (39), wherein the adjusting screw (35, 36) and the locking screw (39) are located in threaded bores on the end faces of the axle journal (20).
Holder according to one of claims 1 through 5, characterized in that the second adjusting device has eccentric bushings (28) that are rotatably arranged in the bores (29) in the bearing branches (6, 7) and that accommodate the bearings.
Holder according to claim 6, characterized in that the eccentric bushings (28) have an annular flange (32) provided with openings or recesses, which flange is located on the outside of the bearing branches (6, 7), and at which flange the rotational position of the eccentric bushings (28) can be locked by means of a screw (34) engaging in an opening (33) or recess.
Holder according to one of the claims 4-7, characterized in that the bearings (24, 25) are plain bearings and have an inner bushing (26) and an outer bushing (27) that are in engagement with one another through congruent spherical sliding surfaces.
Holder according to one of the preceding claims, characterized in that the first arm (2) and the second arm (3) have, at their free ends, receiving bores whose center axes each lie in a plane intersecting the center axes of the bores (21, 29) at a right angle, and are parallel in the operating position of the arms (2, 3) predefined for joining, and have a minimal distance from one another.