DE202009012039U1 - Pneumatic cylinder - Google Patents

Abstract

Pneumatic cylinder, in particular for use in a welding device, for. B. a spot welding gun or a spot welding portal, with a cylinder housing (2) and a piston element (3) having at least one piston rod (4), wherein the piston member (3) and the piston rod (4) relative to the cylinder housing (2) are mounted axially displaceable , characterized in that the cylinder housing (2) is formed from a non-pressure molded polyamide.

Description

The The invention relates to a pneumatic cylinder according to the preamble of claim 1.

From the German utility model DE 92 07 582 a working cylinder is known which has a housing made of an inner tube and an inner tube surrounding the inner tube radially outer. The outer tube is a plastic tube, which may consist of polyvinyl chloride, a polyacetate or a polyoxymethylene. The outer tube is formed as an extruded part or as an extruding part. In particular, this document teaches the use of a plastic of lower quality in terms of strength for the outer tube, which is not subjected to dynamic loads on the outer tube. The use of the mentioned plastics for the outer tube have only the task of ensuring a diverse contouring of the outer circumference with little effort.

From the EP 12 55 046 B1 is a pressure cylinder, in particular for use in the food industry, in which a cylinder tube is encased by a plastic, wherein the plastic is a transparent material. This should have the purpose of being able to detect any existing position sensors for the piston rod from the outside better. The transparent plastic of the housing contributes nothing or only slightly to the strength and stability of the cylinder. The cylinder tube and two end-capped cylinder caps are locked together by threaded rods to form a stable cylinder.

The The aforementioned cylinders are not suitable as pneumatic cylinders for use in a welding plant, in particular in a portal welding machine or multi-point welding machine a welding robot or the like. For this Applications have known cylinder a steel tube as a cylinder tube, in which the piston elements and the piston rod axially displaceable because such cylinders are very resistant, especially with regard to mechanical stress. Usually are such welding cylinder with pressures of operated up to 12 bar and have strokes up to about 180 mm on. Such cylinders are used as an impact point in welding systems as well as drive of spot welding guns, stationary or attached to a robot can be and z. B. in the automotive industry come. As the demands in the automotive industry for shortening the production cycle times get bigger, this means that the robots use the welding guns move faster and faster during idle travel have to. In as far as possible in overdrive and as possible timely from a position of a first welding point to get to a position of a second welding point, The welding guns must be as light as possible be educated. Steel cylinders have a construction-related relatively high dead weight, so that the associated welding guns a have correspondingly high weight, what the dynamic load the robot increases.

Furthermore are such steel cylinders very expensive to manufacture, For example, there is a cylinder tube end with a closure must be provided. At the end of this closure is usually welded. The pressure medium supply, in this case compressed air supply and Abführeinrichtungen must by means of soldered Connection means are provided. Furthermore is It is relatively expensive, fasteners for the To attach steel cylinder to this. Usually welded there holder, which is undesirable in the production Heat distortion leads. From this and also from the soldering processes results in the production of such a cylinder an undesirable Load and unwanted thermal distortion. To meet the high demands on the coaxiality and the tight To be able to meet tolerances of an air cylinder, It is therefore necessary after completion of all heat treatments such a cylinder a precise honing or spindling perform.

Of Further, usually also have detailed galvanic measures, such. B. phosphating performed to ensure adequate corrosion protection.

task The invention therefore is a suitable pneumatic cylinder u. a. for use in welding devices, for example available in welding tongs or welding portals to provide, which on the one hand has a reduced weight and on the other hand, in terms of component strength in the given Boundary conditions reaches the values of a steel cylinder. Especially should the number of manufacturing steps and in the production required items are significantly reduced.

Of Furthermore, a pneumatic cylinder to be specified in simple way in different installation situations customizable and in particular be arranged closely spaced side by side can, so that the distance between two cylinder center axes as possible can be chosen small.

Another object of the invention is to provide a pneumatic cylinder which runs quietly in operation and in particular for installation in a welding / welding tongs in a simple manner electrical insulation the cylinder, in particular its piston rod relative to the remaining welding tongs simply allows.

A Another object of the invention is to provide a pneumatic cylinder specify which in a transverse direction of the cylinder especially slim builds and still a usual for the operation welding tongs or other actuating means necessary compressive force / tensile force can muster.

These Tasks are performed with a pneumatic cylinder with the features of claim 1. Advantageous embodiments are given in the subclaims.

According to the invention was recognized that the multitude of specific requirements for pneumatic cylinders, which are used in welding devices through which Selection of a specific plastic for a cylinder housing can be met, using as plastic a polyamide is selected, which is purged without pressure. Under pressure Poured in the context of the invention is to be understood that the polyamide not as usual in the injection molding or extrusion process under pressure but in a pourable form liquid state without applying external pressure in an open Casting mold is poured. Surprisingly It turned out that the choice of plastic and the type the processing into a particularly strong plastic structure and also to a particularly demanding crystalline design of the plastic leads, so that all application-specific Requirements now for the first time by means of a Kunststoffzylin dergehäuses for the application of the pneumatic cylinder in a welding system can be ensured.

It has even been shown that such a cylinder housing is sufficiently stable, even without metallic inner tube, which forms a bushing for piston elements of the pneumatic cylinder, can work. Of course, however, it may be for certain applications are appropriate, that in the cylinder housing a metal cylinder as a bushing is arranged for the piston element.

According to one Another preferred embodiment is the cylinder housing in the region of a first end of the cylinder housing with Fastening devices provided, which preferably integrally attached to the cylinder housing. It is also available to unilaterally form the cylinder housing, such that, for example, a bottom piece of the cylinder housing and corresponding fastening devices together with the cylinder housing are integrally formed.

Around the closest possible packing and one possible close succession arrangement of several inventive To achieve pneumatic cylinder, it is recommended that the cylinder housing to provide by flattening, so that as close as possible Arrangement of the cylinder is ensured next to each other. It is also useful in thickened areas the cylinder housing to provide measuring means by means of which the position of the piston elements or the piston rod inside the Cylinder is determinable. The measuring means can easily be cast with and / or stored in a groove.

At the second end of the cylinder housing this is by means of a, z. B. metallic closure and sealed, wherein the closure on the one hand to a paragraph in Zylinderge housing rests on the other hand by a so-called Seeger ring axially is held. The Seeger ring sits in a groove in the plastic of the cylinder housing.

When preferred material for the formation of the cylinder housing is a PA12, PA12G or PA6 in question. Appropriately It makes sense, also piston elements or the piston rod to produce from the pressure-released polyamide. this leads to to a further weight reduction and in particular to a quiet and low-wear barrel. Furthermore, this offers Design of the piston / piston rods the possibility Seal elements in the edge region of the piston in one piece pour into the flask and thus the required installation work to reduce.

at the pneumatic cylinder according to the invention it possible in a simple manner the housing for forming a multiple cylinder with a plurality, d. H. To provide two or more cylinder chambers, so that a multi-acting pneumatic cylinder is achievable. This is at the selected Material particularly easy to reach, since the selected Material selected in the invention Processing, namely the Drucklosgießen particularly simple can be machined and, in particular, bores for Cylinder chambers with a very large stroke in proportion to the bore diameter easily and accurately produced are. There are no problems with drilling / lifting conditions in the area can be produced up to 1:12.

In the case of the pneumatic cylinder according to the invention, therefore, the cylinder housing is cast in one piece, wherein the casting takes place in such a way that the low-viscosity polyamide has a starter for the polymerization reaction. In this fluid state, the polyamide is poured into an open mold. The polymerization of the plastic then takes place in the mold, ie the molecular chain formation also takes place in the mold, whereby a very homogeneous and low-stress construction of the casting blank is achieved. This distinguishes the pressureless casting, for example, from the usual injection molding, where it is z. B. comes to certain orientations of the already finished molecular chains and can give in particular in the area of the meeting of two casting fronts weaknesses, such as meet the two melt streams again on the back of a both sides of the melt flown around the core. In injection molding, it may happen that such melt streams no longer bond 100%, since on their surface already on the way a cooling / orientation of the chains has occurred. This problem is known in injection molding as the emergence of a weld line. In contrast, formation of longer molecular chains is observable in the inventive design of the cylinder housing from a pressureless cast polyamide, since a pressing into the mold or pushing through an extrusion die does not occur. After the curing of the polyamide composition in the casting mold, for example, the casting blank can be tempered. This serves for further homogenization and can take in practice, depending on the requirement, about 2 to 6 hours.

Provided used as a bushing for the piston a steel tube is preferably sitting by a clearance in the steel tube Cylinder housing, wherein the clearance on the one hand by Machining the bush and the inner surface of the cylinder housing is achieved.

It it has been shown that if used a metal bushing / metal cylinder is, this end can be open at both ends and in the Operation of the pneumatic cylinder resulting from pressurization Axial forces on the bottom area of the cylinder housing and the closure of the Zylin dergehäuses acting forces without Further through the cylinder housing itself, so the polyamide plastic can be included.

Provided the housing thickened areas or areas with sufficient Has wall thickness, the connection devices for the supply and removal of the pressurized fluid, here Compressed air, mounted directly in the plastic of the cylinder housing be. An additional provision of fittings or the like is no longer necessary. The compressed air supply lines can be screwed directly into the cylinder housing.

Especially It is useful from a variety of flats having cylinder housings and pneumatic device according to the invention formed therefrom Cylinders form a cylinder package and this cylinder package, for example to be provided with a suitable bundling device. A such bundling device can, for example, a shape guide own, so that in each case two adjacent pneumatic cylinders by means mechanically engaging fasteners are connectable. Such shape guides are for example a dovetail guide or T-slots.

All in all is in the pneumatic cylinder according to the invention a great advantage in seeing a variety of yourself primarily conflicting requirements for a pneumatic Cylinder for use in a welding system through the selection of the material could be fulfilled. In particular to emphasize that typically when using a pneumatic Cylinders occurring in a welding system spatter and weld beads in the usual frequency Do not damage the cylinder housing significantly could. This resulted in corresponding experiments.

Of Another is of particular advantage that in the manufacture of a Such a compressed air cylinder a variety of steps, in particular a soldering of connection means for the pressure medium lines, a welding of corresponding holding devices, a phosphating or otherwise galvanic treatment for the purpose of Antirust and / or elaborate machining reworking for Ensuring the cylinder tread accuracy omitted could. This contrasts with a significant cost advantage achieved known cylinder housing made of metal and a considerable simplification of the production of the cylinder possible.

Of Furthermore, it is possible in a particularly simple manner Special shapes and special sizes of cylinders for To provide users as the selected Material pourable without cavities even in large blocks is, so that special sizes of cylinders through Cutting of correspondingly cast polyamide blocks for Can be made available. This succeeds in a reasonable cost, as the selected Plastic can be machined simply and accurately.

Especially it is advantageous when using an inventive Compressed air cylinder without inner metallic bushing that the used material has a high self-lubricating property, so that the operation is also going on for a long time with un-oiled Compressed air can be done.

in the The invention will be explained by way of example with reference to the drawing. Show it:

1 a partially sectioned side view of a pneumatic Zy invention Linders;

2 : A plan view of the cylinder according to 1 ;

3 an isometric view of a cylinder according to the invention;

4 a view of a cylinder composite formed from two single cylinders;

5 a longitudinal section through a second embodiment of the pneumatic cylinder in the embodiment as a multi-cylinder;

6 a plan view of the multi-cylinder according to 5 ;

A pneumatic cylinder according to the invention 1 according to 1 to 4 has a cylinder housing 2 in which at least one piston element 3 together with a piston rod 4 are mounted axially displaceable. In the cylinder housing 2 sits as a bushing for the piston element 3 a metal cylinder tube 5 , In the area of a first end 6 of the cylinder housing 2 owns the cylinder housing 2 fastening devices 7 , which together with a bottom piece 8th the cylinder housing 2 close one-stop. The cylinder housing 2 , the bottom piece 8th and the fastening device 7 are integrally formed. At the opposite second end 9 of the cylinder housing 2 the cylinder housing is open. In the area of the second end 9 closes a closure, in particular a metal closure 10 the cylinder chamber of the cylinder housing 2 , The closure 10 supports one side, for example, frontally on the metal cylinder 5 from. However, also appropriate paragraph inside the cylinder housing 2 be present, against which the shutter 10 is set. Other end is the closure 10 by means of a securing ring 11 , in particular a Seeger ring, which in a corresponding groove 12 in the cylinder housing 2 sits, fixed. The closure 10 has a passage opening 13 for the piston rod 4 on. From the second, open end 9 forth extends in the cylinder housing 2 another groove 14 into which a lead 15 of the lock 10 engages, leaving the shutter 10 regarding the cylinder housing 2 is rotatably mounted. The passage opening 13 has at least a straight line limit 16 on that with a corresponding flat side 17 the piston rod 4 corresponds and thus the piston rod 4 rotationally fixed with respect to the cylinder housing 2 is fixed.

In the area of the first end 6 and / or in the region of the free cylinder wall of the cylinder housing 2 are feeding / discharging devices 18 intended for pressurized fluid, in particular for compressed air.

The cylinder housing 2 the pneumatic cylinder according to the invention 1 is made of a non-pressure molded polyamide and consists in particular of a PA6, PA12 or PA12G.

In a preferred manner, the cylinder housing 2 flats 19a . 19b on which are arranged approximately opposite and parallel to each other. In the area of flattening 19a . 19b can form guides 20 be provided, for example, a dovetail guide, so that adjacently arranged pneumatic cylinder 1 by means of a suitably shaped connecting element in the manner of one of the mold guides 20 corresponding plug-in block 21 can be connected to each other.

By providing the flats 19a . 19b owns the cylinder housing 2 thickened areas 22a . 22b in which expedient manner measuring means (not shown) for determining the position of the piston 3 regarding the cylinder housing 2 are poured.

4 shows an example of a composite of two pneumatic cylinders according to the invention 1 , which by means of a plug stone 21 are composed.

According to a particular embodiment of the invention ( 5 and 6 ) is the pneumatic cylinder according to the invention as a multiple cylinder with an integrally formed cylinder housing 2 educated. In integrally formed cylinder housing 2 sits a plurality, in particular three cylinder bores 30 which each for receiving at least one piston element 3 and a piston rod 4 serve. The cylinder bores 30 serve either for receiving a metal cylinder tube 5 or store directly, without the interposition of a metal cylinder tube 5 the piston rods / piston element unit axially displaceable. Appropriately, the cylinder bores 30 connected by a communicating line with each other, so that by Druckmittelbeaufschlagungseinrichtung 18 all three cylinder bores 30 can be acted upon evenly with pressurized fluid. By such an arrangement, which in particular with a cylinder housing 2 From a non-pressure cast polyamide easily form, particularly narrow multi-cylinder are possible, which allow a small width b high pressure force.

In this case, it is particularly possible cylinder bores 30 form whose diameter / length ratio d / l is particularly small. In particular, diameter aspect ratios are from 1: 8 to 1:12 compared to cylinder housings Metal particularly easy to produce, since the inventively selected unpressurized potted polyamide plastic is particularly easy to machine and even with such unfavorable diameter / length ratios still sufficient manufacturing accuracy can be achieved.

With a pneumatic multiple cylinder according to the 5 to 7 In particular, it is possible to achieve high pressure forces, although the width b of the cylinder housing is very low compared to the height h. By coupling the respective piston rods outside the cylinder housing, it is possible in a simple manner to achieve high pressure forces, since all pistons act in parallel. The resulting surfaces of the individual pistons are relatively small and can be made round in cross-section, so that there is a reduced sealing problem compared to an oval or otherwise freely shaped piston. In particular, cylinders according to the 5 to 7 be arranged very tightly nested. This makes it possible, for example, to realize welding tongs or welding portals with particularly narrow dot patterns. In the field of welding tongs, such a narrow-built cylinder can often accessibility problems such as an excessively large welding tongs z. B. in the body shop, reduced.

1

pneumatic cylinder

2

cylinder housing

3

piston element

4

piston rod

5

Metal cylinder tube

6

first The End

7

fastening devices

8th

breech

9

second The End

10

shutter

11

circlip

12

groove

13

Through opening

14

groove

15

head Start

16

limit

17

flat side

18

Pressure medium supply - / - removal device

19a, 19b

flats

20

form guide

21

plug Stein

30

bore

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 9207582 U [0002]
• - EP 1255046 B1 [0003]

Claims (15)

Pneumatic cylinder, in particular for use in a welding device, for. B. a spot welding gun or a spot welding portal, with a cylinder housing ( 2 ) and one at least one piston element ( 3 ) having piston rod ( 4 ), wherein the piston element ( 3 ) and the piston rod ( 4 ) relative to the cylinder housing ( 2 ) are mounted axially displaceable, characterized in that the cylinder housing ( 2 ) is formed from a non-pressure molded polyamide. Pneumatic cylinder according to claim 1, characterized in that in the cylinder housing ( 2 ) a metal cylinder tube ( 5 ) as a bushing for the piston element ( 3 ) is arranged, in which the piston element ( 3 ) Is mounted axially displaceable. Pneumatic cylinder according to claim 1 or 2, characterized in that the cylinder housing ( 2 ) in the region of a first end ( 6 ) of the cylinder housing ( 2 ) Fastening devices ( 7 ) for fastening the pneumatic cylinder ( 1 ) on a welding device, for. B. a welding gun or a welding portal and the fastening device ( 7 ) and the cylinder housing ( 2 ) are integrally formed. Pneumatic cylinder according to one of the preceding claims, characterized in that the cylinder housing ( 2 ) along its longitudinal extent at least one flattening ( 19a . 19b ) having. Pneumatic cylinder according to one of the preceding claims, characterized in that in thickened regions of the cylinder housing ( 2 ) Measuring means, in particular position sensors cast or inserted into a groove. Pneumatic cylinder according to one of the preceding claims, characterized in that the cylinder housing ( 2 ) Mold guides ( 20 ), so that in each case two adjacent pneumatic cylinders ( 1 ) by means of positively engaging connecting means ( 21 ) are mechanically connectable. Pneumatic cylinder according to one of the preceding claims, characterized in that the cylinder housing ( 2 ) at the other end with a closure ( 10 ) is closed, which on one side on a projection / paragraph or the front side of the metal cylinder tube ( 5 ) and on the other side by means of a Seeger ring ( 11 ), which is in a groove ( 12 ) in the cylinder housing ( 2 ) and the closure ( 10 ) axially against the heel. Pneumatic cylinder according to one of the preceding claims, characterized in that the cylinder housing ( 2 ) for forming a multi-cylinder at least two cylinder chambers ( 30 ) owns. Pneumatic cylinder according to one of the preceding Claims, characterized in that the pressure-sealed Polyamide is a PA12, a PA12G or a PA6. Pneumatic cylinder according to one of the preceding claims, characterized in that at least one piston element ( 3 ) and / or the piston rod ( 4 ) is formed from a non-pressure molded polyamide, in particular from the same material as the cylinder housing ( 2 ) is trained. Pneumatic cylinder according to one of the preceding claims, characterized in that sealing elements of the piston elements ( 3 ) in one piece with the piston ( 3 ) are formed. Pneumatic cylinder according to one of the preceding Claims, characterized in that the sealing elements is designed as a soft lip seal. Pneumatic cylinder according to one of the preceding claims, characterized in that the sealing elements at least partially into the piston elements ( 3 ) are poured. Welding device comprising at least one Pneumatic cylinder according to one of claims 1 to 13. Welding device according to claim 14, characterized in that the welding device is a welding tongs, a portal welding system or a multi-point welding system is.