DE102008018884B4 - Linear drive, system and method - Google Patents

Abstract

Linear drive comprising a first drive comprising a belt (2) or a chain,
a further linear drive being assigned to the first drive as a second drive,
wherein a tool (6) for linear movement of the tool (6) is directly or indirectly connected to the belt (2) or the chain,
a sword (7, 41, 42, 43, 44) made of electrically conductive material being arranged on the belt (2) or on the chain,
At least one stationary disc (5) fitted with permanent magnets (31) and rotatable by an electric motor (1) as the second drive is operatively connected to the sword (7, 41, 42, 43, 44) at times and/or for movement sections. kicks.

Description

The invention relates to a linear drive, a system and a method.

Belt drives include a belt that can be set in motion by means of deflection pulleys. Chain drives include a chain that can be set in motion by means of sprockets, i.e. gear wheels. In the case of the present invention, for the sake of simplicity, the term belt drive is often used, whereby chain drives are also to be understood as meaning.

From the DE 89 09 163 U1 a drive comprising a friction wheel is known, to which an auxiliary drive is assigned.

From the DE 195 42 059 C2 a linear drive is known, of which a further linear drive can be moved, as a result of which the mass to be moved is increased and the dynamics are thus reduced.

From the DD 237 444 A3 a main drive is known, of which a pneumatically operated auxiliary drive is also moved. Thus the mass to be moved is again increased.

From the DE 295 06 374 U1 a combination of a linearly moving component by means of a cable with an eddy current brake is known, the guide part of which is attached to the moving component in accordance with the blade.

From the DE 195 24 485 A1 a drive with a combined but not permanently connected linear and belt drive is known, with each drive being effective in its own areas

From the WO 2003 036 781 A2 a combination of belt drive and linear drive is known, but there is no direct or indirect connection of the runner part with the belt acting as a protective part.

From the DE 10 2006 055 663 A1 a drive principle of a linear motor is known.

The invention is therefore based on the object of making higher dynamics achievable in systems with at least one drive.

According to the invention, the object is achieved with the linear drive according to the features specified in claim 1 or 3, with the system according to the features specified in claim 7 and with the method according to the features specified in claim 10.

Important features of the invention in the linear drive are that it comprises a first drive comprising a belt or a chain,
a further linear drive being assigned to the first drive as a second drive,
wherein a tool is directly or indirectly connected to the belt or chain for its linear movement,
a bar made of electrically conductive material acting on the belt or chain,
at least one stationary arranged, rotatable by a motor, equipped with permanent magnets, rotationally driven disk at times and/or moving sections comes into operative connection with the sword.

The advantage here is that the acceleration or deceleration can be increased in the temporal and/or spatial connection ranges and thus improved dynamics can be achieved. A slight increase in the mass to be moved by the belt drive is sufficient here.

In an advantageous embodiment, the first drive is a belt drive with deflection means, in particular deflection rollers, or a chain drive with deflection means, in particular chain wheels. The advantage here is that existing inexpensive drive means can also be used.

In an advantageous embodiment, a tool is connected directly or indirectly to the belt or the chain for its linear movement, with the tool functioning as a reactive part on the belt and/or on the chain. The advantage here is that a sword can be connected as a reactive part to the tool or to the belt or to the chain and therefore only a small additional mass to be moved is necessary. For example, this reactive part can be designed as sheet metal.

In an advantageous embodiment, the reactive part is encompassed by the second drive and is operatively connected to the stator of a linear motor, in particular a reluctance linear motor, an asynchronous linear motor and/or a synchronous linear motor. The advantage here is that known stators, ie primary parts, can be used and the reactive part can also be constructed in the known manner. The reactive part only needs to be adjusted in the connection area with the tool or the belt or the chain.

In an advantageous embodiment, the reactive part is made of electrically conductive material, in particular with a straight or rounded bevel on at least one end area of the sword. Aluminum is preferably used. The advantage here is that an eddy current motor can be provided as the second drive. Here it is advantageous that the eddy current motor comprises a mechanical rotational energy store.

In an advantageous embodiment, the reactive part has elevations and depressions, which are oriented towards the stator of the linear motor functioning as the second drive and alternate in the direction of movement, in particular for the formation of magnetic poles. The advantage here is that an inexpensive motor can be used.

In an advantageous embodiment, the reactive part of the linear motor functioning as the second drive has permanent magnets that are oriented alternately in the direction of movement. The advantage here is that high forces can be generated in addition to the driving force of the first drive.

In an advantageous embodiment, the stator of the linear motor acting as the second drive and the reactive part are designed in such a way that the reactive part and the stator form a reluctance motor, an asynchronous motor or a synchronous motor. The advantage here is that respective second drives can be used with their respective advantages.

In an advantageous embodiment, the reactive part comes into operative connection with an eddy current motor. The advantage here is that high dynamics can be achieved since an additional mechanical energy store can be provided.

In an advantageous embodiment, the eddy current motor comprises at least one rotationally driven disk equipped with permanent magnets. The advantage here is that production is simple because a cost-effective rotary electric motor only has to drive one or more disks and the reactive part can be designed as a simple sheet metal.

Important features of the invention in the plant, in particular the machine, are that it comprises a linear drive, comprising a belt or a chain, as the first drive,
and a linear drive assigned to the first drive as a second drive,
wherein the second drive can be switched on at times and/or for movement sections.

The advantage here is that the dynamics can be increased at times and/or for movement sections. A mechanical energy store can be filled in the other periods of time.

In an advantageous embodiment, the second linear drive comprises a reactive part which can be brought into operative connection with the stator of a reluctance motor, asynchronous motor, synchronous motor or with a rotary-driven disc fitted with permanent magnets. The advantage here is that simple and inexpensive means are sufficient.

In an advantageous embodiment, the reactive part functions in the direction of movement for such a long time that the second linear drive is effective when the tool is braked to a target position. The advantage here is that the length of the reactive part can be used to control the time or the movement section. The mode of operation of the system can thus be determined in a simple manner.

Important features of the invention in the method for operating a system with a linear drive comprising a belt or a chain as the first drive,
and a linear drive assigned to the first drive as the second drive,
are that the first drive acts to drive a tool,
the second drive being switched on at times and/or for movement sections,
the connection becoming effective when the tool is decelerated to a target position and when it is removed from the target position at an accelerated, in particular positively accelerated, ie not decelerated.

The advantage here is that the second drive only has to be made effective in the movement sections mentioned. In the other periods of time, he can replenish his energy stores. In addition, the target position can be reached with a high level of accuracy.

In an advantageous embodiment, the first and/or the second drive is used as an actuator of a position control, with the position of the tool being detected and used by the control. The advantage here is that the controller can access one or two drives. The control quality and dynamics can therefore be selected as required.

In an advantageous embodiment, only the first drive is effective at the target position, in particular the position control uses only the first drive as an actuator. The advantage here is that no jerks, disruptive forces or the like can be introduced by the second drive.

In an alternative advantageous embodiment, the first and the second drive are effective at the target position; in particular, the position control uses only the first drive as an actuator. The advantage here is that a simple control method can be used.

Further advantages result from the dependent claims. The invention is not limited to the combination of features of the claims. For the person skilled in the art, there are further meaningful combinations of claims and/or individual claim features and/or features of the description and/or the figures, in particular from the task and/or the task posed by comparison with the prior art.

• In der 1 ist eine erfindungsgemäße Vorrichtung und ein Verfahren in Draufsicht und Schnittansicht gezeichnet.

The invention will now be explained in more detail with reference to figures:

• In the 1 a device according to the invention and a method are drawn in plan view and sectional view.

In 1 a drive combination of a device according to the invention is shown, in which an electric motor 1 drives a belt 2 or a chain via a deflection roller 3 . This part is also referred to below as the belt drive. The belt drive functions to perform a linear movement of a tool. The tool 6 is linearly moved back and forth.

The belt drive is preferably designed such that it can be positioned. To this end, it includes a sensor that detects the position of the belt 2 or the chain and/or a sensor that detects the angular position of the output shaft of the electric motor 1 . In this way, positions can be approached very precisely.

In versions without a sensor, it is only possible to control positions, with greater inaccuracies occurring.

In the invention, another linear drive is now functioning, which is also aligned in the linear direction like the belt drive.

In 1 This further linear drive is realized by means of an eddy current motor, which comprises an electric motor 4 which drives discs 5 fitted with permanent magnets 31 .

In 2 this eddy current motor is shown again separately in a schematic oblique view.

In 3 a disc 5 is shown in plan view, with the permanent magnets 31 being oriented radially. Eight permanent magnets 31 are shown here.

A sword made of electrically conductive material, preferably aluminum, acts on the tool 6 . As soon as this sword 7 enters the area between the disks 5, 5 eddy currents are induced because of the rapidly driven disks, which contribute to a force component in the direction of movement. A force generated by the eddy current motor is thus added to the driving force transmitted from the belt drive to the tool 6 .

In various embodiments, the sword 7 is the 1 shaped differently. In 4a a rectangular sword 41 is shown, which quickly makes full power transferrable when entering the eddy current motor. However, the course of the force is theoretically even discontinuous.

In 4b is a bevel on the front end portion of the blade 42, which leads to a steady progression of force when entering the eddy current motor area.

In 4d are each executed a chamfer on the front and rear end portion of the blade 42, whereby a steady flow of force is achieved when entering and exiting the eddy current motor area.

In 4c are compared to 4b and 4d round instead of linear bevels, where in 4c this is only performed on the front end area of the sword 43, which leads to a constantly differentiable force curve when entering the eddy current motor area. In further exemplary embodiments, the bevel is designed to be round at the front and rear.

In 5a An exemplary velocity curve is shown in the absence of the eddy current motor. The tool is accelerated and decelerated again between times t1 and t2 by means of the belt drive. A maximum acceleration and a maximum braking acceleration can be carried out here. The tool is held at the target position between times t2 and t3. The tool is then withdrawn from the target position, first accelerating in the reverse direction and then decelerating.

In 5b an example of the speed curve is shown with an additional eddy current motor. In this case, the tool is again accelerated and braked again between times t1 and t2. A maximum acceleration can be carried out here. The eddy current motor is positioned so that the blade 7 comes into effect at the beginning of the deceleration acceleration time range. Thus, the braking acceleration is much greater than with 5a . The sword is made so short that when the deceleration stops, ie when the target position is reached, the sword leaves the effective range of the eddy current motor. Thus, between the points in time t2 and t3 the tool is only held at the target position by the belt drive. The tool is then withdrawn from the target position, with the sword initially re-entering the effective range of the eddy current motor and thus being accelerated by the eddy current motor together with the belt drive, which leads to a very high acceleration. After exiting the effective range of the eddy current motor, the tool is braked by means of the belt drive, as a result of which the starting position, ie the same as at t1, is reached at time t4.

In further exemplary embodiments, the sword is made so long that it is also effective in the target position. The belt drive then works in the target position, i.e. in the time range between t2 and t3, against the force of the eddy current drive. In one embodiment, it is also possible to equate the times t2 with t3, ie not to remain in the target position but to initiate an immediate retreat from the target position immediately after it has been reached.

In the case of the eddy current motor, it is also important that the high rotational speed of the discs 5 means that large amounts of rotational energy can be stored. Thus, when the eddy current motor becomes effective, ie when the blade enters the effective range of the eddy current motor, more power can be transmitted from the eddy current motor to the tool, that is, at best it can be generated by the electric motor 4 . This is because additional power can be drawn from the mechanical energy store. The moments of inertia of the discs 5 have a positive effect. In such applications, it is even advantageous to design the panes to be particularly solid. Thus, a low-power motor 4 can be used, which constantly fills the mechanical accumulator, with energy being drawn off only in the short periods of time when the eddy-current motor becomes effective.

Another advantage of the eddy current drive is the low mass of the blade, i.e. the reactive part. The drive can therefore be operated in a highly dynamic manner.

Instead of in the 1 and 2 shown eddy current drive, another linear drive can be used. For this purpose, in a first further exemplary embodiment, instead of the electric motor 4 and the rotationally driven disks 5, a stator that generates a rotary field functions. Thus, the sword 7 connected to the tool 6 and the stator generating the rotating field form an asynchronous linear motor. Since the rotary field is generated by a converter supplying current to the stator windings of the stator, faster changes in the rotary field speed can be provided and better control behavior can thus be achieved. Even the linear motor can be used for fine positioning, i.e. for position control towards the target position. However, only the force generated by the rotating field can be supplied. The asynchronous motor has no additional mechanical energy store compared to the eddy current motor.

Instead of an asynchronous linear motor, a synchronous linear motor can also be used, in which the blade is equipped with permanent magnets oriented alternately in the direction of movement, or a reluctance linear motor in which the blade has protruding and retracted elevations in the direction of the stator, which alternate in the direction of movement with their respective functional advantages.

The arrangement of the windings of the respective stator is also known from the prior art in such motors.

The combination of drives according to the invention, i.e. belt drive, comprising belt or chain, and further linear drive, can be used advantageously, for example, in injection molding machines in which the workpiece, after injection molding has been carried out and the workpiece has cooled, the molds are moved apart and then a tool separates the workpiece, i.e the injection molded part, has to mold out of the area between the moulds. This tool, for example a gripper, is moved into the area between the molds by means of the belt drive. Then, the tool grips the workpiece, with means for ejecting the workpiece being actuated in the injection molding machine at the same time or immediately before. The tool then transports the workpiece out. The tool has to move very quickly into the area between the molds and, after gripping, move out again very quickly. With the invention it is now possible to exceed the acceleration limits of the belt drive.

Instead of ejecting and gripping an injection molding machine, the drive according to the invention can also be used with other machines and/or removal robots, as well as with folding adjustments and slides. A packaging machine should also be mentioned here as an example. In particular when stacking soft piece goods, such as handkerchiefs or the like, the tool of the packaging machine also needs to be moved back and forth quickly. However, an increase in the acceleration or deceleration of a linear axis is often advantageous for processing machines as well. Thus, the invention can be used in various machines and systems with a linear axis.

Reference List

1

electric motor

2

strap or chain

3

pulley

4

electric motor

5

slices

6

Tool

7

sword

31

permanent magnets

41

sword

42

sword

43

sword

44

sword

v

speed

t

time

t1

time

t2

time

t3

time

t4

time

Claims (11)

Linear drive comprising a first drive comprising a belt (2) or a chain, with the first drive being assigned a further linear drive as a second drive, wherein a tool (6) for linear movement of the tool (6) is directly or indirectly connected to the belt (2) or the chain, a sword (7, 41, 42, 43, 44) made of electrically conductive material being arranged on the belt (2) or on the chain, At least one stationary disc (5) fitted with permanent magnets (31) and rotatable by an electric motor (1) as the second drive is operatively connected to the sword (7, 41, 42, 43, 44) at times and/or for movement sections. kicks. linear drive after claim 1 , characterized in that the blade (7, 41, 42, 43, 44) has a round bevel at at least one end area. Linear drive comprising a first drive comprising a belt (2) or a chain, wherein a linear motor is assigned to the first drive as a second drive at times and/or for movement sections, wherein a tool (6) is connected directly or indirectly to the belt (2) or the chain for its linear movement, a sword (7, 41, 42, 43, 44) of the linear motor being arranged on the belt (2) or on the chain, which is in operative connection with the stationary arranged stator of the linear motor in the time segment and/or movement segment, wherein the stator of the linear motor acting as the second drive and the sword (7, 41, 42, 43, 44) are designed in such a way that the sword (7, 41, 42, 43, 44) and the stator are a reluctance motor, an asynchronous motor or form a synchronous motor. linear drive after claim 3 , characterized in that when the second linear drive is designed as a reluctance motor, the sword (7, 41, 42, 43, 44) is oriented towards the stator of the linear motor acting as the second drive and has alternating elevations and depressions in the direction of movement to form magnetic poles. linear drive after claim 3 , characterized in that when the second linear drive is designed as a synchronous motor, the blade (7, 41, 42, 43, 44) of the linear motor acting as the second drive has permanent magnets (31) oriented alternately in the direction of movement. Linear drive according to one of the preceding claims, characterized in that the first drive is a belt drive with deflection means, in particular deflection rollers (3), or a chain drive with deflection means, in particular chain wheels. Plant, in particular a machine, comprising a linear drive according to one of the preceding claims. plant after claim 7 , characterized in that the second linear drive comprises a blade (7, 41, 42, 43, 44) which is operatively connected to the stator of a reluctance motor, asynchronous motor, synchronous motor or to a rotary-driven disc (5) fitted with permanent magnets (31). is bringable. plant after claim 8 , characterized in that the blade (7, 41, 42, 43, 44) is designed so long in the direction of movement that when the tool (6) is braked to a target position, the second linear drive is effective. Method for operating a system with a linear drive, comprising a belt (2) or a chain as the first drive and a linear drive assigned to the first drive as the second drive, the first drive for driving a movement tool (6), the second drive being switched on intermittently and/or for movement sections, the tool (6) being connected directly or indirectly to the belt (2) or the chain for its linear movement, - the belt (2) or a sword (7, 41, 42, 43, 44) made of electrically conductive material is made on the chain, with which a stationary arranged, rotatable by a motor, equipped with permanent magnets (31), rotationally driven disc (5) is temporarily and/or or can be brought into operative connection in movement sections or - wherein a sword (7, 41, 42, 43, 44) of the second drive is arranged on the belt (2) or on the chain, which in a time section or movement section in operative connection with a stationary arranged stator of the second drive is, wherein the stator of the second drive and the sword (7, 41, 42, 43, 44) are designed such that the sword (7, 41, 42, 43, 44) and the stator a reluctance motor, a asynchronous motor or form a synchronous motor. switching on when braking the tool (6) towards a target position and when moving away from the target position in an accelerated, in particular positively accelerated, ie not decelerated manner, is made effective. procedure after claim 10 , characterized in that the first and / or the second drive is used as an actuator of a position control, the position of the tool (6) is detected and used by the control.

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