EP3781355B1 - Piston-cylinder device with automatic shut-off, vacuum holder and vacuum support table - Google Patents

Description

Technical area

The invention relates to a piston-cylinder device with automatic shutdown, a vacuum holder and a vacuum support table.

State of the art

The use of pneumatic piston-cylinder devices for handling workpieces is generally known in the prior art. These can for example be designed with a blowing or suction function in order to hold workpieces or to convey them with compressed air. In this case, the overpressure or underpressure provided by an external pressure device is usually controlled via a separate switching valve, which creates a correspondingly high pneumatic and control-related interconnection effort.

Furthermore, the use of vacuum tables for temporarily holding flat workpieces in a stationary manner by means of negative pressure is known in the prior art. Such devices are used to temporarily fix the workpieces at individual processing stations as part of a manufacturing process, for example for machining steps such as grinding, drilling, sawing or milling or, for example, also for gluing or joining components. Such vacuum tables usually consist of a central negative pressure source, for example a vacuum pump, and a support surface through which suction bores or suction holes are penetrated, which are in permanent fluid connection with the negative pressure source. Since the negative pressure is permanently available regardless of the function, the operation is relative energy consuming. In addition, there is a technical challenge in adapting the active area of the vacuum table to the shape and dimensions of the workpiece to be held. In practice, it is known to cover bores or suction holes that remain free with adapter mats, which, however, have to be specially adapted to the shape of the workpiece to be machined and the desired machining geometry.

the GB 892,771 discloses a work table for handling workpieces, in which several vacuum holders are integrated, each of which is formed from a piston-cylinder device with a suction head. The suction heads are arranged within holes in the plate of the work table and are arranged at the upper end of a hollow piston rod, which is formed at its lower end with a piston which is arranged axially movable in a cylinder housing. The suction heads can each be extended via a pressure connection opening into the lower cylinder chamber and can be connected to a vacuum pump and subjected to a negative pressure via a separate pressure connection of the hollow piston rod. By simultaneously applying negative pressure to a pressure connection opening into the upper cylinder chamber and the hollow piston rod, a holding torque is exerted on a workpiece that is sucked in by a suction head. The one from the GB 892,771 disclosed device does not disclose any means for controlling the pressurization with a negative pressure. The hollow piston rods are permanently subjected to negative pressure during operation, regardless of the stress on their function. Since the hollow piston rod is firmly connected to the piston and can therefore only be moved together with it, the pressure connection of the hollow piston rod must be designed to be flexible and is subject to material wear due to the movable connection.

the DE 10 2004 025 781 B4 discloses a vacuum gripper with a mouthpiece which can be acted upon by a negative pressure source and which is connected via a hollow piston rod to a piston of a piston-cylinder device. A control valve for controlling the energy provided by the vacuum source is integrated into the piston-cylinder device, which control valve controls a first action which moves the mouthpiece and a second action which applies a vacuum to the mouthpiece. That of the DE 10 2004 025 781 B4 disclosed in the piston-cylinder device The integrated control valve is functionally built with a large number of individual parts, which is relatively expensive and complex.

the JP 2004142949 A discloses D1 discloses a piston-cylinder device with a suction pipe which is statically arranged in the cylinder housing and a piston which is arranged axially movably thereon and which is formed with a suction head which is arranged outside the cylinder housing. The suction function is controlled by a separate external control device.

the DE 22 49 412 A discloses a piston-cylinder device in which a suction pipe arranged axially movably in a cylinder is formed with a suction nozzle. The device further comprises a lifting sleeve which is arranged axially movably on the cylinder. The control of the travel path of the components of the piston-cylinder device and the provision of the suction air are carried out via an external connection. The one from the DE 22 49 412 A disclosed piston-cylinder device with suction function is functionally built with a large number of individual parts relatively expensive and complex. Document D1 shows the preamble of claim 1.

Disclosure of the invention

The invention is based on the object of avoiding the disadvantages shown. In particular, a piston-cylinder device with a blower or suction function that can be switched off is to be provided, which is constructed as simple and compact as possible in terms of design, can be produced simply and inexpensively and enables energy-efficient operation.

The object is achieved according to the invention by a piston-cylinder device according to claim 1, advantageous embodiments are described in the subclaims.

The essence of the invention is a piston-cylinder device with a dispensing means arranged outside the cylinder housing, in which a suction or pressure pipe which can be brought into fluid connection with a pressure device is provided, which is statically arranged in the cylinder space and on which an axially movable piston with a hollow piston rod is slidably mounted, wherein the hollow piston rod is arranged on the head side of the piston and formed or connected to the dispensing means, and wherein the hollow piston rod or a pipe section connected to it is formed below the dispensing means with an inner sealing plug which, in the retracted position of the hollow piston rod, closes a head-side opening of the suction or pressure tube in a form-fitting manner and releases it with the extension movement of the hollow piston rod, at the same time a fluid connection can be established between the delivery means and the suction or pressure pipe. As a pressure device for use with the piston-cylinder device, depending on the desired function (blowing or suction), a pressure device providing positive or negative pressure comes into consideration, as either a compressed air source, such as a compressor or compressed air reservoir, or a negative pressure source, for example a vacuum pump. The sealing plug is arranged in the hollow piston rod in such a way that the operating fluid can flow around it within the hollow piston rod or through the sealing plug in a corresponding channel guide if there is no form fit between the sealing plug and the suction or pressure pipe. Furthermore, the sealing plug can be formed within a separate pipe section which is screwed onto the hollow piston rod below the dispensing means, for example with a threaded connection, or is screwed into it. In this case, the delivery means is indirectly connected to the hollow piston rod via the separate pipe section, which is arranged between the delivery means and the hollow piston rod. For this purpose, the dispensing means can likewise be screwed onto the pipe section or screwed into it with a threaded attachment.

In a structurally particularly simple embodiment, the cross-sectional area of the stopper or of a projection formed by the stopper is designed to be smaller than the inside diameter of the hollow piston rod or the tube section, and the stopper closes the head-side opening of the suction or pressure tube in the retracted position of the hollow piston rod with a positive fit by engaging them either flush at the front, or by engaging flush with the periphery with a shoulder, or by being designed with a hollow cylindrical shoulder that engages flush around the head-side end of the suction or pressure pipe. In these design variants, the sealing plug is arranged in the hollow piston rod in such a way that the operating fluid can flow around it within the hollow piston rod.

For this purpose, the sealing plug is held in the hollow piston rod or the pipe section, for example via one or more web connections, or at least one material connection is provided between the sealing plug and the wall of the hollow piston rod or the fluid channel penetrating the pipe section.

To improve the sealing fit or to compensate for manufacturing tolerances, the sealing plug is designed with one or more sealing means, via which the form fit to the suction or pressure pipe can be established.

A structurally simple drive with a mechanical return mechanism for the piston is provided in that a cylinder chamber can be acted upon by a pressure medium connection and the piston is designed with a spring return counteracting the direction of application. The spring return can be designed in a structurally simple manner by means of a correspondingly arranged compression or tension spring.

A structurally simple pneumatic return mechanism for the piston is provided in that both cylinder chambers are each designed to be acted upon by a pressure medium connection.

For the pneumatic control of the piston, at least one pressure medium connection can be controlled via a valve. In a structurally simple control solution, the at least one valve is a 3/2-way valve, in the switching positions of which a cylinder chamber connected to it can alternately be acted upon and vented.

In an embodiment in which a pressure medium connection can be controlled via a valve or a 3/2-way valve, the purely pneumatic control of the piston is made possible according to the differential piston principle, in that the piston is designed with two differently sized contact surfaces, with the one that can be acted upon in a controllable manner Cylinder chamber cooperating impact surface is larger than the other impact surface. In this case, both pressure medium connections can be operated with the same pressure and the uncontrolled pressure medium connection can be operated permanently be acted upon. When the cylinder chamber controllably pressurized via a valve is pressurized, the piston moves in this case against the simultaneous permanent pressurization of the other cylinder chamber due to the larger pressurizing surface of the piston that interacts with this cylinder chamber. This enables a considerable simplification of the pneumatic interconnection of the piston-cylinder unit.

In an alternative, structurally simple variant with a purely pneumatic control, in which both cylinder chambers can be acted upon by pressure medium connections, both pressure medium connections can be controlled jointly via a 5/2-way valve, in whose switching positions the two cylinder chambers can alternately be acted upon and vented.

In the valve-controlled design variants, a particularly compact design is ensured in that the valve or valves is or are arranged directly on or in the cylinder housing.

The piston-cylinder unit can be used as a vacuum holder or vacuum gripper in that the pressure device is designed as a suction device and the suction or pressure pipe can be subjected to a negative pressure via the suction device. To improve the frictional connection to a workpiece or object to be held, the delivery means is preferably designed as a suction head or suction plate with one or more suction openings or suction nozzles.

In the above embodiment, several vacuum holders serve as vacuum support tables, in that the vacuum holders are physically connected to one another, the delivery means or the suction heads or suction plates forming a support grid.

Fig. 1

eine schematische Schnittdarstellung einer Kolben-Zylindereinheit mit eingefahrener Kolbenstange,

Fig. 2

eine schematische Schnittdarstellung der Kolben-Zylindereinheit nach Fig. 1 mit ausgefahrener Kolbenstange,

Fig. 3

eine schematische Darstellung der Kolben-Zylindereinheit nach Fig. 1 mit eingefahrener Kolbenstange im Funktionszusammenhang mit einem 3/2-Wegeventil und permanenter Beaufschlagung der oberen Zylinderkammer,

Fig. 4

eine schematische Darstellung der Kolben-Zylindereinheit nach Fig. 1 mit eingefahrener Kolbenstange im Funktionszusammenhang mit einem 5/2-Wegeventil,

Fig. 5

eine perspektivische Darstellung einer aus mehreren Kolben-Zylinder-Einrichtungen gebildeten Batterie.

Fig. 6

eine perspektivische Darstellung eines aus mehreren Batterien gemäß Fig. 5 gebildeten Vakuum-Auflagetischs.

Further advantages of the invention are set out below together with the description of preferred exemplary embodiments of the invention on the basis of FIG Figs. 1 to 6 shown in more detail. Show it:

Fig. 1

a schematic sectional view of a piston-cylinder unit with retracted piston rod,

Fig. 2

a schematic sectional view of the piston-cylinder unit according to FIG Fig. 1 with extended piston rod,

Fig. 3

a schematic representation of the piston-cylinder unit according to Fig. 1 with retracted piston rod in functional connection with a 3/2-way valve and permanent pressure on the upper cylinder chamber,

Fig. 4

a schematic representation of the piston-cylinder unit according to Fig. 1 with retracted piston rod in functional connection with a 5/2-way valve,

Fig. 5

a perspective view of a battery formed from a plurality of piston-cylinder devices.

Fig. 6

a perspective view of one of several batteries according to Fig. 5 formed vacuum support table.

the Fig. 1 and 2 show the piston-cylinder device 1 with the hollow piston rod 2. The hollow piston rod 2 is slidably arranged on the suction or pressure pipe 4 which is fixedly connected to the cylinder 3 and is statically arranged in it. In Fig. 1 the hollow piston rod 2 is in its retracted position. In Fig. 2 the hollow piston rod 2 is in its extended position. The suction or pressure pipe 4 is designed on the bottom side with a pressure device connection 5 via which the suction or pressure pipe 4 is connected to a (in the Fig. 1 and 2 pressure device (not shown) can be connected and can be brought into a fluid connection therewith. The hollow piston rod 2 is arranged on the head side on the piston 6 and can be moved together with it on the suction or pressure pipe 4. The hollow piston rod 2 is formed on the head side with the delivery means 7, which is used to deliver a suction or pressure effect via the central opening 8, depending on whether an overpressure or a negative pressure is provided by a pressure device connected to the pressure device connection 5. is the pressure device connection 5 with a negative pressure source, for example a vacuum pump (in Fig. 1 and 2 not shown) connected, the piston-cylinder device 1 can be used as a vacuum holder. The hollow piston rod 2 with the inner sealing plug 9 is formed below the dispensing means 7. The sealing plug 9 is held firmly in the hollow piston rod 2 by means of a material connection, through which the fluid channels 10 and 10 'penetrate. The stopper 9 is formed with the extension 11, which has a smaller cross section than the inner diameter of the hollow piston rod 2. In the retracted position of the hollow piston rod 2, the stopper 9 engages with the cylindrical extension 11 in the head-side tube opening 12 of the suction or Pressure pipe 4 flush on the circumference, wherein it closes the suction or pressure pipe 4 in a form-fitting manner. To improve the sealing fit of the extension 9 in the suction or pressure pipe 4, the cylindrical extension 11 can be designed with a circumferential O-ring seal (in Fig. 1 and 2 not shown). With the outward movement of the hollow piston rod 2, the plug 9 releases the head-side tube opening 12 of the suction or pressure tube 4, a fluid connection being established between the suction or pressure tube 4 and the dispensing means 7 at the same time. The cylinder 3 is formed with the upper pressure medium connection 14 opening into the cylinder chamber 13 located above the piston 6 and the lower pressure medium connection 14 'opening into the cylinder chamber 13' located below the piston 6. The cylinder chambers 13 and 13 'can be acted upon with a fluid via the pressure medium connections 14 and 14', whereby the piston 6 can be moved upwards or downwards. Since the head-side impact surface 15 of the piston 6, which interacts with the upper cylinder chamber 13, is smaller, due to the head-side arrangement of the hollow piston rod 2 on the piston 6, than its bottom-side impact surface 15 'which interacts with the lower cylinder chamber 13', the piston 6 is based on the differential piston principle operable. When both impingement surfaces 15 and 15 'are acted upon with identical pressure at the same time, the piston 6 moves upwards due to the larger effective area of the impingement surface 15' on the bottom. To enable a position query, the piston 6 can be designed as a magnetic piston, with one or more inductive sensors being provided on or in the cylinder 3 at the same time (in Fig. 1 and 2 not shown.

Fig. 3 shows the piston-cylinder device 1 in a schematic functional representation with the 3/2-way valve 16. The hollow piston rod 2 is located in FIG Fig. 3 in their retracted position. The 3/2-way valve 16 is used to control the pressure medium connection 14 '. It is shown in accordance with Fig. 3 in its first switching position, in which the pressure medium connection 14 ′ is connected to the compressed air outlet 18 via the valve connection 17. In this switching position of the 3/2-way valve 16, the lower cylinder chamber 13 ′ is vented via the compressed air outlet 18. The upper pressure medium connection 14 is connected to the compressed air inlet 19. The upper cylinder chamber 13 is permanently exposed to the pressure P1 via the compressed air inlet 19. In its second switching position, the 3/2-way valve 16 connects the pressure medium connection 14 'via the valve connection 17 to the compressed air inlet 19'. In this switching position, the lower cylinder chamber 13 'is also acted upon by the pressure P1 via the compressed air inlet 19'. Due to the larger effective area of the bottom-side impingement surface 15 ', the piston 6 moves upwards in the second switching position of the 3/2-way valve 16.

Fig. 4 shows the piston-cylinder device 1 in a schematic functional illustration with the 5/2-way valve 20. The hollow piston rod 2 is located in FIG Fig. 4 in their retracted position. The 5/2-way valve 20 is used to control the two pressure medium connections 14 and 14 '. It is shown in accordance with Fig. 4 in its first switching position, in which the pressure medium connection 14 'is connected to the compressed air outlet 18' via the valve connection 17 '. The lower cylinder chamber 13 'is vented in this switching position of the 5/2-way valve 20 via the compressed air outlet 18'. At the same time, in this switching position of the 5/2-way valve 20, the upper pressure medium connection 14 is connected to the compressed air inlet 19 ″ via the valve connection 17 ″ of the 5/2-way valve 20. In this switching position of the 5/2-way valve 20, the upper cylinder chamber 13 is acted upon via the compressed air inlet 19 ". In its second switching position, the 5/2-way valve 20 connects the pressure medium connection 14 'via the valve connection 17' to the compressed air inlet 19". In this switching position, the lower cylinder chamber 13 'is acted upon via the compressed air inlet 19 ". At the same time, the upper pressure medium connection 14 is in the second switching position of the 5/2-way valve 20 via the valve connection 17" of the 5/2-way valve 20 with the Compressed air outlet 18 ". The upper cylinder chamber 13 is vented in the second switching position of the 5/2-way valve 20 via the compressed air inlet 18". Since the upper cylinder chamber 13 is vented in the second switching position of the 5/2-way valve 20 and the lower cylinder chamber 13 'is acted upon at the same time, the piston 6 moves upwards in the second switching position of the 3/2-way valve 16.

Fig. 5 shows eight similar piston-cylinder devices 1 '(in Fig. 5 For the sake of clarity, only one of the illustrated piston-cylinder devices 1 'is numbered), which are physically connected to one another as a battery. The piston-cylinder devices 1 'are each designed with a valve 21 on the bottom side (in Fig. 5 only one of the valves 21 is numbered for the sake of clarity). The piston-cylinder devices 1 'are each designed at their upper end with a discharge means designed as a suction plate 22 (in Fig. 5 only one of the suction cups 22 is numbered for the sake of clarity). The suction plates 22 each have a central suction opening 23.

Fig. 6 FIG. 14 shows the vacuum support table 24, which is made up of several similar, physically connected batteries according to FIG Fig. 5 is formed (in Fig. 6 for the sake of clarity, only one of the illustrated piston-cylinder devices 1 'is numbered). The suction pads 22 (in Fig. 6 for the sake of clarity, only one of the suction plates 22 is numbered) form a common support grid for receiving a workpiece.

List of reference symbols

1, 1 '

Piston-cylinder device

2

Hollow piston rod

3

cylinder

4th

Suction or pressure pipe

5

Printer connection

6th

Pistons

7th

Means of delivery

8th

opening

9

Sealing plug

10, 10 '

Fluid channel

11

approach

12th

Pipe opening

13, 13 '

Cylinder chamber

14, 14 '

Pressure medium connection

15, 15 '

Impact area

16

3/2-way valve

17, 17 ', 17 "

Valve connection

18, 18 ', 18 "

Compressed air outlet

19, 19 ', 19 "

Compressed air inlet

20th

5/2-way valve

21

Valve

22nd

Suction pad

23

Suction opening

24

Vacuum support table

Claims (14)

1. Piston-cylinder device, comprising a delivery means arranged outside the cylinder housing, a suction or pressure tube (4) which can be brought into fluid connection with a pressure device being provided, which tube is statically arranged in the cylinder cavity and on which an axially movable piston (6) having a hollow piston rod (2) is slidably mounted, the hollow piston rod (2) being arranged on top of the piston (6) and being formed together with or connected to the delivery means (7),
   characterized in that the hollow piston rod (2) or a tube portion connected thereto has an inner closure plug (9) below the delivery means (7), which plug closes a top opening (12) of the suction or pressure tube (4) in a form-fitting manner when the hollow piston rod (2) is in the drawn-in position and opens said opening when the hollow piston rod (2) draws out, it being possible to establish a fluid connection between the delivery means (7) and the suction or pressure tube (4) at the same time.
2. Piston-cylinder device according to claim 1, characterized in that the cross-sectional area of the closure plug (9) or of a projection (11) formed by the closure plug (9) is smaller than the inner diameter of the hollow piston rod (2) or of the tube portion, and the closure plug (9) closes the top opening (12) of the suction or pressure tube (4) in a form-fitting manner when the hollow piston rod (2) is in the drawn-in position by lying flush on the end of said tube, engaging circumferentially flush in said tube by means of a projection (11), or having a hollow cylindrical projection which engages flush around the top end of the suction or pressure tube (4).
3. Piston-cylinder device according to claim 1, characterized in that the closure plug (9) is held in the hollow piston rod (2) or the tube portion via one or more bridge connections or at least one fluid channel (10, 10') that penetrates the hollow piston rod or the tube portion is provided in a material connection between the closure plug and the wall of the hollow piston rod or the tube portion.
4. Piston-cylinder device according to any of claims 1 to 3, characterized in that the closure plug has one or more sealing means via which the form fit with the suction or pressure tube (4) can be established.
5. Piston-cylinder device according to any of claims 1 to 4, characterized in that a cylinder chamber (13, 13') can be pressurized via a pressure medium connection (14, 14') and the piston (6) has a spring return that acts counter to the pressurization direction.
6. Piston-cylinder device according to any of claims 1 to 4, characterized in that the two cylinder chambers (13, 13') are each designed to be pressurized via a pressure medium connection (14, 14').
7. Piston-cylinder device according to claim 6, characterized in that at least one pressure medium connection (14, 14') can be controlled via a valve (21).
8. Piston-cylinder device according to claim 7, characterized in that the at least one valve (21) is a 3/2-way valve (16), in the switching positions of which valve a cylinder chamber (13') connected thereto can be alternately pressurized and vented.
9. Piston-cylinder device according to any of claims 6 to 8, a pressure medium connection being controllable via a valve or a 3/2-way valve, characterized in that the piston (6) has two differently sized pressurizing surfaces (15, 15'), the pressurizing surface (15') that interacts with the controllably pressurizable cylinder chamber (13') being larger than the other pressurizing surface (15).
10. Piston-cylinder device according to claim 6, characterized in that both pressure medium connections (14, 14') can be jointly controlled via a 5/2-way valve (20), in the switching positions of which valve the two cylinder chambers (14, 14') can be alternately pressurized and vented in alternate directions.
11. Piston-cylinder device according to any of claims 7 to 10, characterized in that the valve (21) or valves is or are arranged directly on or in the cylinder housing.
12. Vacuum holder comprising a piston-cylinder device according to any of claims 1 to 11, characterized in that the pressure device is designed as a suction device and the suction or pressure tube (4) can be subjected to a negative pressure via the suction device.
13. Vacuum holder according to claim 12, characterized in that the delivery means (7) is designed as a suction head or suction plate (22) having one or more suction openings (23) or suction nozzles.
14. Vacuum support table comprising a plurality of vacuum holders according to either claim 12 or claim 13, characterized in that the vacuum holders are physically interconnected, the delivery means (7) or the suction heads or suction plates (22) forming a support frame.

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