CN118176076A - Method for automatically transferring a workpiece to a tooth machine - Google Patents

Abstract

The invention relates to a method for automatically transferring workpieces, in particular workpieces having a diameter of more than 200mm and/or a weight of more than 100kg, to a tooth machine for tooth machining of the workpieces, in which method a workpiece is clamped at a supply position by two clamping arms which perform a relative movement with respect to one another in a motor-wise manner, and in the clamped state by the two clamping arms is moved from the supply position in a motor-wise manner along a movement path to a receiving position of the tooth machine by means of a joint movement of the two clamping arms, wherein the joint movement is caused by at least two motor drives which are controlled in a coupled manner, wherein one motor drive is a first motor drive which contributes to or causes the relative movement.

Description

Method for automatically transferring a workpiece to a tooth machine

The invention relates to a method for automatically transferring workpieces, in particular workpieces having a diameter of more than 200mm and/or a weight of more than 100kg, to a tooth machine for tooth machining of the workpieces, in which method a workpiece is clamped at a supply position by two clamping arms which perform a relative movement with respect to one another caused by means of a motor, and in a state clamped by the two clamping arms, is moved from the supply position along a movement path by means of a motor to a receiving position of the tooth machine by means of a combined movement of the two clamping arms.

The loading of tooth machines by means of loading systems with gripping arms is well known in the art, for which purpose the most widely used should be a ring loader system, as it is disclosed for example in DE 10 2017 005 756 A1. Such a ring loader has several gripper units, for example two (angular spacing of 180 °), three (angular spacing of 120 °) or four (angular spacing of 90 °), each having two gripper arms. A common metronomic motor ensures that each gripper unit is constantly clocked between individual positions (e.g., processing stations, infeed and/or outfeed positions, and other processing stations as appropriate). In this way, the loading and unloading times can be greatly shortened and an advantageous ratio of auxiliary time to main time can be achieved. In some applications, particularly when working with large-sized workpieces, this ratio is not taken into account, and for such systems, depending on the workpiece size, a loading system like a crane is used in order to hoist the workpiece to the machine tool turntable of the toothed machine.

The object of the present invention is to improve a method of the above-mentioned type in an advantageous manner, in particular for workpieces of larger dimensions.

The invention is based on a method which is characterized in that the joint movement is caused by at least two motor drives which are controlled in a coupled manner, wherein one motor drive is the first motor drive which contributes to or causes the relative movement.

The invention is based on the recognition here that, although the above-mentioned conventional ring loader has many advantages, these cannot counteract the disadvantages of material design reinforcement anymore in the case of larger workpiece sizes, but in conventional loading systems it is still possible to increase the degree of automation for large-sized workpieces.

In a particularly preferred embodiment, there are no other gripping arms than two, and the loading system has just two gripping arms. This saves material and weight while reducing the ratio of secondary time to primary time.

In a particularly preferred embodiment, the clamping arm and/or the motor drive for its relative movement is designed to hold workpieces having a diameter of still more than 300mm, even more than 450mm, still more than 600mm and/or a weight of more than 150kg, still more than 200kg, even more than 400kg or still more than 600kg or more. It is to be understood that the clamping arms are designed with correspondingly high rigidity for this purpose, and that the drives assigned to these clamping arms can also apply correspondingly high torques in the case of force-fitting holding of the workpiece.

In a further preferred embodiment, it is provided that a second of the at least two motor drives is a second drive which can be used to cause a relative movement, and in particular both motor drives cause a relative movement for clamping the workpiece.

In the case of a joint coupling movement, the coupling control is preferably arranged such that if it is arranged for force-fit retention, the non-pushing clamping arm exerts a counter-torque which has a torque limitation, in particular a torque limitation. Such mechanically equivalent moment limitation with springs counteracting the joint movement and acting on the non-pushing gripping arms is preferably achieved by control techniques.

In a preferred embodiment, the movement path comprises a path segment of circular arc shape, and in particular a circular path when projected onto the movement plane. This design can be easily combined with a column base around which the movement is performed.

In a further preferred embodiment, the movement path comprises a path section having an axial, in particular vertical, movement component caused by the third motor drive. This increases the flexibility of the method and allows for different levels of elevation for each station, as well as allowing for skipping work pieces in a station to position the clamp arm.

In a preferred embodiment, the respective gripper arm motion paths traversed by one of the gripper arms when gripping and moving a workpiece overlap. Therefore, the movement locus is restricted by the forced guide, which improves the positioning safety and reliability with a simple structure.

In a further preferred embodiment, it is provided that the workpiece is moved after processing into a storage position, which is in particular different from the supply position, in particular in the same direction of movement as the path of movement, and the clamping arm is moved again in particular from the storage position into the supply position for clamping a next workpiece, in particular in the opposite direction of movement. In this way, for example, a new workpiece can be prepared in advance for machining at the supply position, without waiting for the workpiece being machined to return to the supply position after tooth-making machining, and the efficiency of the loading method can be improved.

In an apparatus technical aspect, the present invention provides a loading system for automatically conveying a workpiece to a tooth machine for tooth machining of the workpiece, the loading system having: two clamping arms for clamping a workpiece in a supply position while performing a motor-induced relative movement with respect to each other; means for performing a joint movement of the two gripping arms from the providing position along a movement path to a receiving position of the toothed machine, the loading system being primarily characterized by at least two motor drives which are coupled controlled in a first operating mode for the joint movement, wherein one motor drive is the first motor drive which contributes to or causes a relative movement in a second operating mode.

The advantages of the loading system of the present invention have been derived from the above explanation of the method of the present invention. Variants are contemplated in which two drives are used to move one gripper arm. In this way, in the first operating mode, a total of four motors are controlled in a coupled manner.

In terms of construction, it is preferred that the loading system has at least one base, in particular a cylindrical base, with respect to which the two first and second clamping arms are arranged to be absolutely movable, in particular pivotable. For this purpose, the clamping arm can be provided with a vertically corresponding support which moves along a rail, in particular a circular rail, and with respect to which the clamping arm can move vertically.

The positive guide described above is provided such that the pivoting movement of the two clamping arms has a common center.

By means of such a circular movement path around a common center, an infinite rotation of the clamping arm is in principle achieved, which allows a role exchange in a simple way as described below, and a kinematic claw is provided which is used by switching to the other side of the clamping arm. However, there is preferably also a variant in which the pivoting movement of one and/or both clamping arms is limited to less than 360 °, preferably less than 340 °, in particular less than 320 °. This provides a simpler, more reliable design.

Furthermore, it is provided that a clamping jaw, in particular a replaceable clamping jaw, is fastened to one clamping arm, which clamping jaw in particular has two contact surfaces arranged at an angle. With respect to the design of the contact surface arranged at an angle, what is achieved is: workpieces of different sizes can still be held with the same jaw. However, since the two clamping arms are forced by their movement not parallel to one another but in the shape of scissors, the workpiece does not have to be positioned symmetrically on the contact surface, but is held slightly offset during the force-fit holding. In this context, it is preferably provided that the angle of the contact surface with respect to the radial direction is at least half the angle between the two clamping arms when holding the workpiece, preferably at least 1 °, more preferably at least 2 °, in particular at least 3 ° and above. For the exchangeable clamping jaws, it is also considered to provide a set of clamping jaws with different angles to the radial direction and/or different total radial elongation. The contact surface may also be curved with different (cut) angles exceeding the above mentioned angles.

As already explained above, the clamping arm with the clamping jaw can be designed for force-fitting retention and/or load-bearing retention; in the latter case, an L-shaped step or a flange extending in radial and tangential directions may be provided in the clamping jaw.

Furthermore, as already mentioned above, a linear movement axis is preferably provided, which has a direction component orthogonal to the movement plane, in particular the pivot plane. If a horizontal movement plane, different height levels can thus be approximated individually or jointly.

The invention furthermore provides a tooth-making processing station with a tooth-making machine having a workpiece spindle which is embodied in particular as a self-contained workpiece spindle for tooth-making processing of workpieces, and also a loading system according to one of the above-described aspects.

Preferably, the ratio of the free radial length of the clamping arm to the distance of the center of its pivoting movement from the workpiece spindle axis is less than 88%, preferably less than 84%, in particular less than 80%. This reduces the requirements on the rigidity and bending rigidity of the clamping arm and the holding structure.

The drive means for the circular movement of the clamping arm causes the drive coupling via a drive track, such as a toothed ring track.

The second rail, which serves either as an additional drive rail or as a guide rail, is preferably arranged in the vertical direction at a distance of preferably at least 40cm, in particular at least 60 cm.

Toothed couplings are considered in connection with drive transmissions, but driven friction wheels or other drive/rail technologies, for example, running on running rails are also considered. In a preferred design, a fixing bracket for fixing the clamping arm is arranged between two (annular) rail designs, at which the clamping arm is preferably also axially movable, preferably vertically movable.

As already explained above, preferably only exactly two fixing brackets are moving at the (endless) track, each of which fixes exactly one clamping arm. In a preferred embodiment, the drive means for moving the fixed support along the track are arranged to operate with the fixed support. The drives for the vertical movement of the clamping arms relative to their respective fixing supports can be arranged to operate together in one variant, in another variant spatially fixed and preferably arranged inside a column-shaped base whose central axis defines the center of the workpiece's circle of flight during movement in a projection plane orthogonal to the force of gravity.

Further details, features and advantages of the invention will emerge from the following description with reference to the drawings, in which:

FIG. 1 shows a schematic view of a loading system;

FIG. 2 shows a loading system and its various approximations;

FIG. 3 shows one loading cycle of the loading system;

FIG. 4 shows another loading cycle of the loading system;

FIG. 5 shows the loading system with the clamp arms in different relative positions;

FIG. 6 shows another design of a loading system;

FIG. 7 shows a side view of the loading system;

fig. 8 shows a top view of the loading system of fig. 7.

In the schematic view of fig. 1, a workpiece W shown without outline is held between the jaws 1a and 2a of the clamping arms 1 and 2. The clamping arms 1, 2 are arranged pivotable with respect to a base 10 (schematically shown as a ring) and extend substantially radially with respect to a common center Z. The pivot angle alpha ₁、α₂ with the reference axis X may be adjustably varied. For this purpose, each of the clamping arms 1, 2 has a motor drive assigned to it, which is not shown in the schematic illustration of fig. 1. Their clamping motion balance is a circular trajectory in a plane orthogonal to gravity.

In the operating mode provided for gripping the workpiece W, the two gripping arms 1 and 2 are moved in opposite directions by correspondingly controlling the driving means thereof so as to approach each other and grip the workpiece W. Correspondingly, if the clamping arms 1, 2 are to be released from the workpiece W, the clamping arms 1, 2 are moved away from each other. For these modes of operation, one clamping arm is thus moved independently of the other clamping arm; different workpieces W, W' may be clamped (fig. 5). Conversely, if the workpiece W is to be moved, the two clamping arms 1, 2 act as a pair and are correspondingly coupled so as to be jointly moved in each case in a clockwise or counterclockwise direction, while maintaining the relative position to one another.

In addition to the illustration of fig. 1, other positions approximated by the clamping arms 1 and 2 are also shown in fig. 2. Here, B denotes a supply position at which a workpiece that has not been machined by the tooth making machine is supplied. The position a (in the illustration of fig. 2, in which the workpiece W is currently held by the clamping arms 1, 2) represents a receiving position of the tooth machine, for example a rotary table, in which the workpiece W is positioned and placed. After the work piece W has been processed in position a, the work piece is moved to a storage position C from which it can be further transported away.

As can be seen in fig. 2a, the approximated position A, B, C may be arranged at a position of about 120 ° to each other. However, since preferably only the two gripper arms 1, 2 are exactly realized, rather than several pairs of gripper arms as in conventional ring loaders, any configuration in the pivot path for the station/position A, B, C is conceivable in terms of angular position. The clamping arms 1 and 2 are in the supply position B in fig. 2B and in the storage position C in fig. 2C.

A preferred cycle for loading the workpiece W will now be shown by figure 3. Here, fig. 3a shows a pivoting movement of about 120 ° which moves the workpiece W from the supply position B to the receiving position a, for example a machine tool rotary table, for processing. Fig. 3C shows the movement of the processed workpiece W from the receiving position a to the storage position C. This movement, likewise of about 120 °, is performed in the same rotational direction as the charging process shown in fig. 3 a. In order to now pick up the next workpiece from the supply position B, the gripper is moved in the opposite rotational direction to fig. 3a and 3c, during which the receiving position a is reached again (without workpiece), wherein a total of about 240 ° of (counter-clockwise) movement is performed. In this variant it is not necessary that the holder is able to pivot infinitely about the base 10. Rather, the respective pivotability is limited, here to about 300 °.

The steps of fig. 3a, 3c and 3b are then repeated for more cycles of each workpiece.

In another embodiment, which is explained by fig. 4, the clockwise movement of fig. 4a and 4c is identical to the clockwise movement of fig. 3a and 3c, which has already been explained. Only in the movement step of returning again to the supply position, the gripper is not moved counter-clockwise as before, but is moved further clockwise (directly) from the storage position C to the supply position B. The swivel bearings of the clamping arms 1,2 are configured for this configuration to be infinitely rotatable.

In this variant, the two gripper arms can also be repositioned by pivoting the gripper arm running in front (not carrying the workpiece) in fig. 4a clockwise by 330 °, i.e. to the shown position of the other gripper arm, and then moving the other gripper arm by about 30 ° to the position of the preceding gripper arm. As shown in fig. 6, if the clamping arms 1, 2 have further different clamping jaws 1a ', 2a' on the side opposite to the clamping jaws 1a, 2a, the clamping jaws do not need to be replaced (in other cases, in order to accommodate different workpieces beyond a certain size range), but only the positions of the clamping arms need to be exchanged, and the other pair of clamping jaws 1a ', 2a' can be used. The clamping jaws 1a, 2a are shaped with contact surfaces in the form of a "V" with an obtuse angle apex. The sides of the "V" may also be curved or even curved in a circle. In order to hold the workpiece in a supported manner, it is conceivable to modify the workpiece to a horizontal placement surface.

In a preferred embodiment, a high mobility of the clamping arms 1,2 is also provided, i.e. a movement in or against the direction of gravity g. For this purpose, two variants are also conceivable, namely the realization of independent individual height adjustability for each individual clamping arm 1,2 with respective individual drives which can be controlled by means of couplings to achieve synchronous joint upward or downward movements, but also individual controls, the latter also being conceivable, for example, in order to achieve a positional exchange of the clamping arms in design variants in which unlimited rotatability is not provided.

In a further embodiment, the upward or downward movement of the two holding arms can also be mechanically positively coupled, in particular by means of a common drive. In this way, a height range adjustment of at least 20cm, in particular at least 40cm, more preferably at least 60cm is achieved, for example to compensate for a height level difference between the individual positions A, B, C, or for lifting the individual clamping arms 1,2 individually or both simultaneously over the workpiece in order to position and clamp the workpiece.

In a further embodiment not shown in the figures, the stations A, B, C may also be arranged, for example, in different geometries, for example, linearly one after the other. In this case, the movement locus of the workpiece may also be linear, and the clamp arm may be movable along a linear rail. It will be appreciated that the shape of the movement path is not further limited and that due to the design of the clamping arms and their bearings in terms of construction the movement may follow other curved paths, but is preferably a (flying) circular path as shown projected onto a plane orthogonal to the direction of gravity.

An embodiment of the present invention will be explained in more detail with reference to fig. 7 and 8. In fig. 7 is depicted a base of a loading system in the form of a column 11, the lower column region 11a with a column foot 11b carrying two rails 12 mounted at a height spacing and extending annularly around the column 11. At least one of the tracks 12 is configured as a drive track. In the embodiment shown, the track takes the form of a toothed annular track for a gear drive coupling/toothed track drive coupling, but other variants are also conceivable, such as a running track for friction wheels or the like. The second rail can also be used as a drive rail for the driven coupling or as a guide rail. In the latter case, for example, the running track is used as a free-running guide roller.

Between or in this embodiment surrounding the two rails, two vertical support clamps 14 are provided, which are movable in circumferential direction along the rail 12. Corresponding drives are also provided at the vertical support clamps 14 for movement therewith, wherein the motor itself is not shown. Thus, the two gripping arms 1, 2 (fig. 8) mounted at the respective support jigs 14 can be moved independently of each other in the circumferential direction (for gripping/releasing the workpiece W) or controlled in a coupled manner (for moving the workpiece W along a circular motion trajectory on a projection plane orthogonal to the gravity force), as described in detail above.

The clamping arms 1 and 2 are also vertically movable; for this purpose, the radially outward surface of the vertical support clamp is designed as a displacement rail. In one embodiment, the vertical displaceability can be achieved by a common drive, which is arranged, for example, inside the lower column region 11a and which engages with the two clamping arms 1, 2. Instead of one drive for the vertical movement, two separate drives can also be implemented, in each of which one engages with one of the clamping arms 1 and 2. In an alternative design of the two independent vertical drives, they can also be arranged in a running-along manner at the vertical support clamp 14 itself.

The component mounted at the column 11 is indicated with 18 and is independent of the loading procedure itself, but can be used, for example, as a support for a shaft-like workpiece during machining or, for example, as a support for a cover covering the workpiece during machining.

The variants shown in fig. 7 and 8 are designed, for example, for workpieces with a workpiece diameter of 1200 mm. In the lowest position of the clamping arm, a clearance of about 400mm from the ground is still achieved. In this embodiment, the vertical travel of the clamp arm is about 800mm. In this embodiment, the distance from the column central axis (center of the flycircle movement of the workpiece) to the workpiece spindle axis of the machine tool table of the tooth machine, which in the figure passes through the center of the workpiece in the machining position (fig. 8), i.e. the position held by the clamping arms 1 and 2, is about 1150 mm.

In the present exemplary embodiment, the clamping jaw is an integral part of the clamping arms 1, 2, having a flange region protruding in the circumferential direction, on which the workpiece W rests. In the illustration of fig. 8, a different contact surface structure of the clamping arm is provided on the side facing away from the held workpiece W, which contact surface structure is provided for smaller-diameter workpieces. If this contact surface is to be used, for example, the two clamping arms 1 and 2 can be pivoted individually in opposite directions of rotation to the right in fig. 8 and then together again in the same direction of rotation back to the left, so that the two clamping arms 1 and 2 exchange their positions with each other, the original outer sides now pointing to the inner sides.

The invention is not limited to the features explained in the above specific embodiments. Rather, the various features of the foregoing description, as well as the following claims, may be presented as essential elements of the various embodiments of the invention, either individually or in combination.

Claims (15)

1. A method for automatically transferring workpieces, in particular workpieces having a diameter of more than 200mm and/or a weight of more than 100 mm, to a tooth machine for tooth machining of the workpieces, in which method a workpiece (W) is clamped at a supply position (B) by two clamping arms (1, 2) which perform a motor-induced relative movement with respect to one another and, in the clamped state by the two clamping arms, is moved from the supply position along a movement path by a motor to a receiving position (A) of the tooth machine,

Wherein the joint movement is caused by at least two coupled controlled motor drives, one of which is the first motor drive which contributes to or causes the relative movement.

2. Method according to claim 1, in which method a second one of the at least two motor drives is a second drive which can be used to cause the relative movement, and in particular both motor drives cause the relative movement to clamp the workpiece.

3. The method according to claim 1 or 2, in which the movement track comprises a track segment of circular arc shape.

4. Method according to one of the preceding claims, in which the movement path comprises a path section having an axial, in particular vertical, movement component caused by a third motor drive.

5. Method according to one of the preceding claims, in which method the respective gripper arm motion trajectories traversed by one of the gripper arms when gripping and moving the workpiece are overlapping.

6. Method according to one of the preceding claims, in which method the workpiece is moved after machining to a storage position (C), which storage position is in particular different from the supply position, in particular in the same direction of movement as the path of movement is traversed, and the gripper arm is in particular moved again from the storage position to the supply position for gripping a next workpiece, in particular in the opposite direction of movement.

7. A loading system (100) for automatically transferring a workpiece to a tooth machine for tooth machining of the workpiece, the loading system having: two clamping arms (1, 2) for clamping a workpiece (W) in a supply position (B) while performing a motor-driven relative movement with respect to one another; means for performing a combined movement of the two gripping arms from the supply position along a movement path to a receiving position (A) of the toothed machine,

Characterized by at least two motor drives which are coupled in a first operating mode for the joint movement, wherein one motor drive is the first motor drive which contributes to or causes the relative movement in a second operating mode.

8. Loading system according to claim 7, having at least one base (10), in particular a cylindrical base, the two first and second clamping arms being arranged to be absolutely movable, in particular pivotable, relative to the base.

9. Loading system according to claim 8, characterized by a common center (Z) of pivotal movement of the two clamping arms.

10. Loading system according to claim 8 or 9, in which the pivoting movement of one and/or both clamping arms is limited to less than 360 °, preferably less than 340 °, in particular less than 320 °.

11. Loading system according to claims 7 to 10, in which a clamping jaw, in particular a replaceable clamping jaw (1 a,2 a), is fixed at one clamping arm (1, 2), which clamping jaw in particular has two contact surfaces arranged at an angle.

12. Loading system according to claims 7 to 11, in which the clamping arms with the clamping jaws are designed for force-fit retention and/or load-bearing retention.

13. Loading system according to claims 7 to 12, having a linear movement axis with a directional component orthogonal to a movement plane, in particular a pivot plane.

14. Tooth-making processing station with a tooth-making machine with a workpiece spindle, in particular embodied as a rotary table, for tooth-making processing of workpieces, characterized by a loading system according to one of claims 7 to 13.

15. Tooth-making station according to claim 14, in which the ratio of the free radial length of the clamping arm to the distance of the centre of its pivoting movement to the workpiece spindle axis is less than 88%, preferably less than 84%, in particular less than 80%.