Method for automatically feeding a workpiece to a gear cutting machine

Abstract

The present invention relates to a method for automatically transporting a workpiece, in particular having a diameter of more than 200 mm and / or a weight in particular of more than 100 kg, to a gear cutting machine where the workpiece is subjected to gear cutting, in which the workpiece is gripped at a preparation spot by two gripper arms which perform a mutual relative movement brought about by a motor, and while gripped by both gripper arms, is moved from the preparation spot along a movement path to a receiving spot of the gear cutting machine by a common movement of both gripper arms by a motor, the common movement being brought about by at least two motor drives which are driven and controlled in a coupled manner, one of which is a first motor drive which contributes to or brings about the relative movement.

Description

[Technical field]

[0001] The present invention relates to a method for automatically transporting a workpiece, in particular having a diameter of more than 200 mm and / or a weight in particular of more than 100 kg, to a gear cutting machine for performing the gear cutting process on said workpiece, in which the workpiece is gripped at a preparation spot by two gripper arms which perform a mutually relative movement brought about by a motor and, while gripped by both gripper arms, is moved from the preparation spot to a receiving spot of the gear cutting machine along a movement path by a common movement of both gripper arms by the motor. [Background technology]

[0002] Such loading of gear cutting machines by means of loading systems with gripper arms is widely known in the art and in this respect ring loader systems, as disclosed for example in DE 10 2017 005 756 A1, are considered to be the most widespread. Ring loaders of this kind have a number of gripper units, each with two gripper arms, for example two (at an angular interval of 180°), three (at an angular interval of 120°) or four (at an angular interval of 90°). By means of a common timing motor, each gripper unit is further timed between the individual positions, such as the processing station, the waiting spot and / or the pick-up spot and possibly also further processing stations. In this way, loading and unloading times can be kept very short and a favourable ratio of non-productive time to main productive time can be achieved. In many applications, especially those involving larger size workpieces, this ratio is less critical and for such systems, depending on the size of the workpiece, a loading system on a crane is also used to lift the workpiece onto the machine rotary table of the gear cutting machine. Summary of the Invention

[0003] The object on which the invention is based is to develop a method as mentioned at the outset in an advantageous manner, in particular for workpieces of larger dimensions.

[0004] From a method-technical point of view, the invention is solved by a development of the method as mentioned at the beginning, which is essentially characterized in that a common movement is brought about by at least two motor drives which are driven and controlled in tandem, one of which is a first motor drive which contributes to or brings about the relative movement.

[0005] The invention is now based on the realization that although the above-mentioned conventional ring loader systems are no longer able to compensate for the extended material design for larger workpiece dimensions, there is still the advantage that a higher level of automation can be achieved with conventional loading systems for large workpiece dimensions.

[0006] In a particularly preferred configuration, there are no other gripper arms apart from the two gripper arms, and the loading system only has these two gripper arms, which saves material and weight at the expense of a worsening ratio of non-productive time to main productive time.

[0007] In one particularly preferred embodiment, the gripper arms and / or the motor drives for their relative movement are designed to hold workpieces having a diameter of more than 300 mm, or even more than 450 mm, or even more than 600 mm, and / or a weight of more than 150 kg, or even more than 200 kg, or even more than 400 kg, or even more than 600 kg, or even more. It is understood that the gripper arms have a correspondingly high stiffness for this purpose, and that, if the workpiece is held by a force coupling, the drives associated with the gripper arms can also apply correspondingly high torques.

[0008] In one further preferred embodiment, a second motor drive of the at least two motor drives is a second drive usable for providing relative motion, in particular both motor drives provide relative motion for gripping a workpiece.

[0009] In the common coupled movement, the coupled drive control is preferably provided in such a way that the non-pushed gripper arm applies a torque-limited, in particular rotationally-limited, counter torque if a force-coupled holding is intended. A spring of this kind is mechanically equivalent to a spring acting on the non-pushed gripper arm resisting the common movement and is preferably realized by the drive control technique.

[0010] In one preferred configuration, the path of movement includes arcuate path sections, and in particular is a circular path when projected onto the plane of movement, which can be combined well with a columnar base around which the movement takes place.

[0011] In one further preferred configuration, the movement path includes a path section with an axial, in particular vertical, movement component provided by a third motor drive, which increases the flexibility of the method and allows for varying the height levels of the individual stations and skipping of workpieces at stations that position the gripper arms.

[0012] In one preferred configuration, the gripper arm movement paths followed by each of the gripper arms when gripping and moving a workpiece overlap, thus restricting the movement paths under forced guidance, which improves the safety and reliability of positioning with a simple structure.

[0013] In one further preferred configuration, the workpiece is transferred after its processing, in particular to a storage spot different from the preparation spot, in particular in the same direction of movement along the path of movement, and the gripper arm moves again, in particular from the storage spot, towards the preparation spot in order to grip the next workpiece, in particular in the same direction of movement, which means that, for example, a new workpiece is already prepared for processing at the preparation spot, and the loading process is more efficient, since it is not necessary to wait for the workpiece to return to the preparation spot again after the tooth cutting of the workpiece currently being processed.

[0014] From an apparatus technical point of view, the present invention provides a loading system for automatically transporting a workpiece to a gear cutting machine which performs gear cutting on the workpiece, the loading system comprising two gripper arms for performing a mutual relative movement brought about by a motor to grip the workpiece at a preparation spot location and means for performing a common movement of both gripper arms from the preparation spot along a movement path to a receiving spot of the gear cutting machine, the loading system being substantially characterized in that there are provided at least two motor drives which are driven and controlled in conjunction in a first operating mode used for the common movement, one of the two motor drives being a first motor drive which contributes to or brings about the relative movement in a second operating mode.

[0015] The advantages of the loading system according to the invention are already clear from the above description of the method according to the invention. A variant is also conceivable in which two drives are used to move the gripper arms, in which case a total of four motors are driven in conjunction in the first operating mode.

[0016] Structurally, the loading system preferably has at least one base, in particular in the form of a column, on which both the first and the second gripper arms are absolutely movable, in particular pivotally mounted, For this purpose, suitable vertical supports for the gripper arms can be provided, which are movable along a rail, in particular along a ring rail, and with respect to which the gripper arms are vertically movable.

[0017] As regards the forced guidance already mentioned above, the pivoting movement of both gripper arms has a common centre.

[0018] With such a circular path of movement with a common center, an essentially infinite rotation of the gripper arms can be realized, which allows for a simple role exchange, as described further below, and a kinematic clamping jaw by switching to another gripper arm surface. However, variants are also preferred in which the pivoting movement of one and / or both gripper arms is limited to less than 360°, preferably less than 340°, in particular less than 320°. This results in a constructionally simpler and more reliable arrangement.

[0019] Furthermore, in terms of construction, a gripper jaw, in particular exchangeable, is fixed to the gripper arm, in particular with two contact surfaces arranged at an angle. With regard to the configuration of the contact surfaces arranged at an angle, it becomes possible that workpieces of different sizes can also be held with the same clamping jaw. However, since the two gripper arms are not parallel across their forced guide but are positioned in a scissor-like manner relative to one another, the workpieces do not necessarily have to be positioned symmetrically at the contact surfaces, but are held slightly offset when held by force coupling. In this connection, the angle of the contact surfaces with respect to the radial direction is preferably at least half the angle made by the two gripper arms when holding the workpiece, preferably at least 1°, more preferably at least 2°, in particular at least 3°. With regard to the exchangeable gripper jaws, gripper jaw sets may be provided, which gripper jaws have different angles with respect to the radial direction and / or a total radial extension. The contact surfaces may be curved, but with various (tangential) angles lying above these angles.

[0020] As already explained above, the gripper arm with the gripper jaws can be designed for force-coupled holding and / or load-bearing holding, in the latter case the gripper jaws can be provided with radially and tangentially extending flanges or L-shaped steps.

[0021] Furthermore, as also already mentioned above, linear movement axes are preferably provided which have a direction component perpendicular to the movement plane, in particular the pivoting plane, so that in the horizontal movement plane different height levels can be reached, either individually or jointly.

[0022] Furthermore, the invention also covers a gear cutting station having a gear cutting machine with a workpiece spindle, which is implemented in particular as an internal part, for carrying out gear cutting on a workpiece, as well as a loading system according to one of the aforementioned embodiments.

[0023] Preferably, for tooth cutting stations, the ratio of the free radial length of the gripper arm to the distance from the workpiece spindle axis to the centre of the swivel movement of the gripper arm is less than 88%, preferably less than 84%, in particular less than 80%, which relaxes the stiffness and bending stiffness requirements for the gripper arm and holding structure.

[0024] The drive for the circumferential movement of the gripper arms provides a drive connection via a drive rail, such as a toothed ring rail.

[0025] The second rail, which may be used as an additional drive rail or which may be used as a guide rail, is preferably arranged in the vertical direction at a distance of preferably at least 40 cm, in particular at least 60 cm.

[0026] In terms of drive transmission, a geared connection is conceivable, but also for example a driven friction wheel running on a running rail or other drive / rail technologies. In a preferred configuration, a holding support for holding the gripper arm is arranged between both (ring) rail structures, in which the gripper arm is preferably further movable in the axial direction and preferably also in the vertical direction.

[0027] As already explained above, preferably exactly two holding supports, each holding exactly one gripper arm, rotate on the (ring) rail. In one preferred configuration, the drives for moving the holding supports along the rail are arranged to move together with the holding supports. The drives for vertically moving the gripper arms relative to their respective holding supports can in one variant be arranged to move together, in another variant they are spatially fixed, preferably arranged inside a columnar base, the central axis of which, projected onto a plane perpendicular to gravity, defines the center of the workpiece (travel) circle during its movement. [Brief description of the drawings]

[0028] Further details, features and advantages of the invention will become apparent from the following description, which refers to the accompanying drawings. [Figure 1] A schematic diagram of the loading system is shown. [Diagram 2] 1 shows a loading system having various reachable positions. [Diagram 3] 1 shows a loading cycle of the loading system. [Figure 4] 4 shows another loading cycle of the loading system. [Diagram 5] 1 shows a loading system with different relative positions of the gripper arms. [Figure 6] 1 illustrates another configuration of the loading system. [Figure 7] FIG. 2 shows a side view of the loading system. [Figure 8] FIG. 8 shows a plan view of the loading system of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] In the schematic diagram of Fig. 1, the workpiece W is represented without contour as it is held between the gripper jaws 1a, 2a of the gripper arms 1, 2. The gripper arms 1, 2 are arranged pivotably on a base 10, which is shown diagrammatically as a ring, and extend substantially radially to a common centre Z. The pivot angles α1, α2 to a reference axis X are adjustable and therefore variable. For this purpose, each gripper arm 1, 2 has its own dedicated motor drive, which is not shown in the schematic diagram of Fig. 1. The gripper movement balance of the motor drives in a plane perpendicular to the direction of gravity is a circular orbit.

[0030] In the operating modes provided for gripping the workpiece W, the two gripper arms 1, 2 are moved in opposite directions by corresponding drive controls of their drives in order to move towards each other and grip the workpiece W. Correspondingly, the gripper arms 1, 2 are moved away from each other in order to move the gripper arms 1, 2 away from the workpiece W. Thus, for these operating modes, the gripper arms are moved independently of each other and can grip different workpieces W, W' (FIG. 5). In contrast, when the workpiece W moves, the two gripper arms 1, 2 function as a pair and are driven in a corresponding coupled manner to move together in a clockwise or counterclockwise direction while maintaining their respective positions relative to each other.

[0031] In Figure 2 further positions are shown, in addition to those shown in Figure 1, which the gripper arms 1, 2 can reach. Here, B represents a preparation spot where a workpiece that has not yet been processed by the gear cutting machine is prepared. In Figure 2, position A, where the workpiece W is actually held by the gripper arms 1, 2, represents a receiving spot of the gear cutting machine, for example a rotary table, on which the workpiece W is positioned and placed. After processing of the workpiece W in position A, it is transferred to a storage spot C, from where it can be further removed.

[0032] As is evident from Fig. 2a, the arrival spots A, B, C can be arranged at approximately 120° to each other. However, since preferably only the two gripper arms 1, 2 are realised and not several gripper arm pairs as in the case of conventional ring loaders, any configuration of angular positions on the swivel path of the stations / spots A, B, C is conceivable. In Fig. 2b the gripper arms 1, 2 are shown at the preparation spot B and in Fig. 2c at the storage spot C.

[0033] A preferred cycle for loading a workpiece W is described with reference to FIG. 3. FIG. 3a shows a common pivoting movement of about 120°, by which the workpiece W is transported from a preparation spot B to a receiving spot A, such as a machine rotary table, for processing. FIG. 3c shows the transport of the already processed workpiece W from the receiving spot A to a storage spot C. This movement, which is also about 120°, takes place in the same direction of rotation as the loading according to FIG. 3a. Now, in order to pick up the subsequent workpiece from the preparation spot B, the gripper moves in the opposite direction of rotation to FIG. 3a and FIG. 3c, reaching the receiving spot A again (where no workpiece is present), and thus performing a movement of about 240° (counterclockwise) overall. With this variant, it is not required that the gripper can rotate infinitely around the base 10. Rather, the respective pivoting possibility is limited, here to about 300°.

[0034] Furthermore, the steps of Figures 3a, c and b are repeated periodically for another workpiece.

[0035] In the alternative configuration, which is described on the basis of Fig. 4, the movements made in the clockwise direction in Fig. 4a and 4c correspond to the movements already described in Fig. 3a and 3c. In the movement step back to the preparation spot again, the gripper does not move counterclockwise as in the previous step, but further moves clockwise (directly) from the storage spot C to the preparation spot B. The rotational bearings of the gripper arms 1, 2 are arranged for this configuration such that they can rotate infinitely.

[0036] In this variation, the positions can also be swapped by the leading gripper arm in FIG. 4a (without a workpiece loaded) pivoting 330° clockwise, i.e. to the position shown in the figure of the other gripper arm, and the other gripper arm moving forward by about 30° to the position of the other gripper arm mentioned above. If the gripper arms 1, 2 have another different gripper jaw 1a', 2a' on the opposite side to their own gripper jaw 1a, 2a side, as shown in FIG. 6, no clamping jaws are required to be provided in a different way to accommodate different workpieces beyond a certain size range, but it is enough to swap the positions of the gripper arms and use another pair of clamping jaws 1a', 2a'. The clamping jaws 1a, 2a are designed in such a way that the contact surface has a "V"-shaped obtuse apex angle. The legs of the V may be curved or may extend so as to be curved until they are circular. It is also conceivable to modify them with a horizontal contact surface to maintain support of the workpiece.

[0037] In one preferred configuration, the gripper arms 1, 2 can also be moved in height, i.e. towards or against the direction of gravity g. Here too, two variants are conceivable: for each individual gripper arm 1, 2, the independent and separate height adjustments with their respective separate drives can be either driven jointly for a synchronized common upward or downward movement or driven separately. The latter, in a conceivable variant, also allows for an interchange of the positions of the gripper arms in configuration variants where infinite rotation possibilities are not provided.

[0038] Alternatively, the upward or downward movement of both gripper arms may also be mechanically forcibly coupled and in particular may even be realized via only one common drive. In this way, an adjustment in a height range of preferably at least 20 cm, in particular at least 40 cm, more preferably at least 60 cm, is realized, whereby, for example, height level differences between the individual positions A, B, C are compensated for or the individual gripper arms 1, 2, individually or both, are raised above the workpiece for positioning and gripping the workpiece.

[0039] In another configuration, not shown in the drawings, the stations A, B, C may be arranged one after the other, for example in a linear manner, with a different geometry. In this case, the movement path of the workpiece is also considered to be linear and the gripper arms may be movable along a linear rail. The shape of the movement path is not further limited and it is understood that the movement can also follow other curved paths depending on the structural configuration of the gripper arms and their bearings, however the circular trajectory shown in the drawings in projection onto a plane perpendicular to the direction of gravity g is considered to be preferred.

[0040] In the following, an embodiment of the invention will be explained in more detail with reference to figures 7 and 8. In figure 7, the base of the loading system is shown in the form of a column 11, the lower column area 11a with the column foot 11b of which supports two rails 12 mounted at a distance in height and which run in the form of a ring around the column 11. At least one of these rails 12 is configured as a drive rail. In the illustrated embodiment, this is in the form of a toothed ring lane for a gear drive connection / toothed rail drive connection, however, other variants such as a running rail for friction gears etc. are also conceivable. The second rail may likewise be used as a running rail for the drive connection or as another guide rail. In the latter case, it may for example be used as a running rail for a free-running guide roller.

[0041] Between the two rails, or in this embodiment surrounding them, two vertical support clamps 14 are provided, which can move in the circumferential direction along the rail 12. The respective drives for this purpose are provided on the vertical support clamps 14 so that they can move together, but the motors themselves are not shown here. Thus, both gripper arms 1, 2 (FIG. 8) attached to each support clamp 14 are either movable in the circumferential direction independently of each other (to grip / release the workpiece W) as explained in detail above, or are driven and controlled in a coupled manner (to move the workpiece W along a circular movement path in a projection plane perpendicular to gravity).

[0042] The gripper arms 1, 2 can also be moved vertically; for this purpose, the radially outwardly facing surface of the vertical support clamp is formed as a moving rail. In one configuration, the vertical movement can be realized via one common drive, which is arranged, for example, inside the lower pillar area 11a and acts on both gripper arms 1, 2. Instead of one drive for the vertical movement, two independent drives can also be realized, each of which acts on one of the gripper arms 1, 2. In an alternative configuration of two independent vertical drives, they can also be arranged on the vertical support clamp 14 itself so that they move together.

[0043] A component on the column 11 is provided with the reference symbol 18, which is not related to the loading process itself but can be used, for example, as a corresponding support for a wavy workpiece during processing or can be used, for example, as a support for a cover which covers the workpiece during processing.

[0044] The variant shown in Figures 7 and 8 is designed, for example, for a workpiece with a workpiece diameter of 1200 mm. In the lowest gripper arm position, a distance of about 400 mm from the bottom is further achieved. In this embodiment, the vertical stroke of the gripper arm is about 800 mm. In this embodiment, the distance from the central axis of the column (center of the circular travel path of the workpiece) to the workpiece spindle axis of the machine table of the gear cutting machine, which in the drawing runs through the workpiece center point in the processing position (Figure 8) of the positions held by the gripper arms 1, 2, is about 1150 mm.

[0045] In this embodiment, the gripper arm jaws are integral components of the gripper arms 1, 2 and have a flange area projecting in the circumferential direction, against which the workpiece W comes into contact. On the side opposite the held workpiece W in FIG. 8, the contact surface structure of the gripper arms is configured differently and is designed for workpieces with smaller diameters. To use this, for example, both gripper arms 1, 2 can be swiveled individually in mutually opposite rotational directions, to the right in FIG. 8, and then together back again to the left in the same rotational direction, so that the positions of both gripper arms 1, 2 are swapped, and in the swapped position the faces of both gripper arms 1, 2 which were previously facing outwards now face inwards.

[0046] The present invention is not limited to the features described in the specific examples above, but rather each individual feature of the above description, as well as the following claims, is considered essential, either alone or in combination, to realize the invention in its various embodiments.

Claims

1. 1. A method for automatically transporting workpieces, in particular having a diameter of more than 200 mm and / or a weight of more than 100 kg, to a gear cutting machine which performs gear cutting on the workpieces, comprising: A method in which a workpiece (W) is gripped at a preparation spot (B) by two gripper arms (1, 2) performing a mutually relative movement brought about by a motor, and is moved, while gripped by both gripper arms, from the preparation spot (B) along a movement path to a receiving spot (A) of the gear cutting machine by a common movement of both gripper arms brought about by a motor, The method is characterized in that the common movement is brought about by at least two motor drives that are driven and controlled in a coupled manner, one of the two motor drives being a first motor drive that contributes to or brings about the relative motion.

2. 2. The method of claim 1, wherein a second motor drive of the at least two motor drives is a second drive usable for providing the relative motion, and in particular both motor drives provide the relative motion for gripping the workpiece.

3. The method of claim 1 , wherein the path of movement includes an arcuate path segment.

4. 2. The method according to claim 1, wherein the movement path includes a path section having an axial, in particular vertical, movement component provided by a third motor drive.

5. The method of claim 1 , wherein the gripper arm movement paths followed by each of the gripper arms when gripping and moving the workpiece overlap.

6. 2. The method according to claim 1, wherein after processing the workpiece, the workpiece is transported to a storage spot (C) different from the preparation spot, in particular in the same direction of movement as when following the movement path, and the gripper arm moves again, in particular from the storage spot, towards the preparation spot to grip the next workpiece, in particular in the same direction of movement.

7. A loading system (100) for automatically transporting a workpiece to a gear cutting machine that performs gear cutting on the workpiece, comprising:

1. A loading system (100) comprising two gripper arms (1, 2) for performing a relative movement effected by a motor to grip a workpiece (W) at a preparation spot (B), and means for performing a common movement of both gripper arms from said preparation spot to a receiving spot (A) of said gear cutting machine along a movement path, A loading system (100) characterized in that at least two motor drive units are provided that are driven and controlled in a coupled manner in a first operating mode used for the common movement, and one of the two motor drive units is a first motor drive unit that contributes to or brings about relative motion in a second operating mode.

8. 8. The loading system according to claim 7, wherein both the first gripper arm and the second gripper arm have at least one absolutely movable, in particular pivotally mounted, base (10), in particular a column.

9. 9. A loading system according to claim 8, wherein a common centre (Z) of pivotal movement of both gripper arms is provided.

10. 10. A loading system according to claim 8 or 9, wherein the pivoting movement of one and / or both gripper arms is limited to less than 360[deg.], preferably less than 340[deg.], in particular less than 320[deg.].

11. 8. The loading system according to claim 7, wherein gripper jaws (1a, 2a), in particular exchangeable ones, having two contact surfaces arranged in particular at an angle, are fixed to the gripper arms (1, 2).

12. 8. The loading system of claim 7, wherein the gripper arms with gripper jaws are designed for force-coupled holding and / or load-bearing holding.

13. 8. The loading system according to claim 7, wherein a linear movement axis is provided having a direction component perpendicular to the movement plane, in particular the pivot plane.

14. 8. A gear cutting station, comprising a gear cutting machine, in particular having a workpiece spindle implemented as a rotary table, for cutting the gears of workpieces, characterized in that the loading system according to claim 7 is provided.

15. 15. The gear cutting station according to claim 14, wherein the ratio of the free radial length of the gripper arm to the distance from the workpiece spindle axis to the center of the pivoting movement of the gripper arm is less than 88%, preferably less than 84%, in particular less than 80%.

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