GB2032975A

GB2032975A - Clip Chain Track

Info

Publication number: GB2032975A
Application number: GB7933945A
Authority: GB
Original assignee: Lindauer Dornier GmbH
Current assignee: Lindauer Dornier GmbH
Priority date: 1978-10-12
Filing date: 1979-10-01
Publication date: 1980-05-14
Also published as: DE2844432C2; JPS5552847A; IT7968985A0; IT1119388B; FR2438606A1; FR2438606B1; DE2844432A1

Abstract

A clip chain track for a tenter frame, for example for stretching a web of plastics film or textile fabric, comprises a frame (2), clips (4) mounted on upper and lower pairs of rollers (11, 11'; 12 12') which roll on upper and lower pairs of support rails (5, 5'; 6, 6'). The rails are of continuous, circular polygonal or oval section steel wire. The roller surfaces are shaped to co-act with the exposed wire surface. The wire rails are carried in bearing grooves (7, 7'; 8, 8') and help by T clamps (10, 10'). <IMAGE>

Description

SPECIFICATION Clip Chain Track This invention relates to a clip chain track comprising tenter clips carried by rollers running on support rails, the rollers being arranged to bear against the contact surfaces of the rails on both sides of the plane in which the clips are mounted.

Clip chain tracks having support rails are known for use in a tentering frame for textile and foil stretching. The rollers for the clips (which grip the edges of a web of material being transported through the frame for stretching) are guided on these rails and supported by them against the vertical and horizontal forces to which they are subjected. In a clip chain track as disclosed in German Patent No. 1,635,250, the runway and supporting rail which takes up the weight of the chain is a flat rail arranged on the lower U-shaped part of the clip chain track. Another clip chain track in which the runway and supporting rail is arranged vertically is disclosed in German Patent No. 1 ,925,284. In this track, the weight of the clip chain is taken up by supporting elements resting on the edge of an upright supporting and track rail.Lastly, in a clip chain track as disclosed in German Patent No. 2,558,765, the weight bearing and supporting rollers rest on the edges of a vertically placed runway and supporting rail.

These edges are parallel to the plane of the web being stretched, and the rollers of at least some of the clips are supported on both edges of the rail.

One of the main disadvantages of these known runway and guiding or supporting rails is that since they are formed by separate bands of differing dimensions arranged to form a rail packet, the contact or rolling surfaces on which the supporting rollers of the clips rest are not sufficiently flat. The clip rollers therefore do not run smoothly and quietly over the rails, especially if the clip chain is moving at high speed. Added to this, apart from the relatively great weight of the rails, is the rather difficult longitudinal displacement of the individual, closely packed bands joined together to form the rail packet, especially in the regions of curvature and deflection. Moreover, the manufacture of such a rail packet entails considerable material, manufacturing and assembly costs, and manufacturing precision is required at the butt joints of the individual bands.

It is therefore an object of the invention to provide track runway and supporting rails so constructed that the working surfaces are plane throughout so as to ensure smooth rolling of the clip rollers over the rails. The rails should be arranged to be longitudinally displaceable in their bearings to allow for the slight changes in length which occur as the clip rollers roll over the runway surfaces, and they should also be simple to manufacture, assemble and service. There should also be a saving in material and weight, and particularly a reduction in the number of supporting and track rollers required and hence a simplification of the clips and saving in weight.

According to this invention, there is provided a clip chain track comprising tenter clips carried by rollers running on support rails mounted in a track support, the rollers being arranged to bear against the contact surfaces of the rails, wherein the rails are disposed above and below the mounting plane of the clips, are of small cross section, and are arranged pair-wise to be longitudinally displaceable in bearings shaped to receive them and carried by the track support, the contact surfaces of the rollers being adapted to the shape of the rails for running thereon.The main advantage of the invention is that the rails are mounted to be longitudinally displaceable in their bearings arranged in the chain track support above and below the plane in which the clips are mounted, and the rollers arranged on the clips in the same plane and to both sides of the rails, bear against the rails so as to be supported against the vertical and horizontal forces to which they are subjected during stretching of a web of material.

It is therefore possible to construct the chain track support in such a manner that above and below the clip mounting plane, it incorporates bearings in which the rails are carried pair-wise. The use of rails of small cross section, and particularly the use of standard wire of small cross section, ensures smooth, quiet running of the rollers over the rails, especially at the high speeds used for stretching a web of plastics foil. Another advantage, apart from the increase in running velocity, is that such an arrangement enables the dimensions in general and the number of rollers to be reduced so that a saving in weight and cost is achieved. Further, bending of the rails is equalised in all the pianes.

The rails may vary in cross section (e.g. they may be circular, polygonol, or oval), the bearings being then shaped accordingly. The rails may be mounted in bearings arranged pair-wise on the upper and lower sides of the chain track support, in each case facing the clip mounting plane and adapted in shape to the cross section of the rails.

The distance between the rails is thus fixed.

The possibility of longitudinal displacement of the rails in their bearings, which is necessary on account of the compression produced during movement of the rollers and consequent deformation by heat, may be provided by means of a T-shaped clamp. The rails in their bearings are only partly covered at the top by these clamps, so that a part of rail surface remains exposed and serves as the contact and rolling surface for the rollers. The clamps may be fixed to the chain track support by screws.In the relatively short regions of deflection and curvature of the clip chain track, the rails are not supported over their whole length in their bearings but, to compensate for the radius of curvature, are supported only on narrow connecting bars which have bearing elements and are mounted so as to be displaceable transversely to the movement of the clips, on surfaces provided for the purpose on the chain track support. The rails are held in the bearings of these connecting bars by appropriate clamps. To counteract wear and tear on the rails by the rollers, the rails may be made of wear resistant but sufficiently elastic material (e.g. Cr Ni steel).

Embodiments of the invention will now be described by way of example, with reference to the drawings, in which: Figure 1 is a section through a clip chain track having supporting rails arranged pair-wise on a track support, with supporting and track rollers bearing against the rails; Figure 2 is an enlarged section of a portion of the chain track support of Figure 1; Figure 3 is a top plan showing a portion of a lower chain track support in a region of curvature, with track runway and supporting rails mounted on the support in connecting bars; and Figure 4 is a section through the chain track support on the plane AB of Figure 3.

Figure 1 is a schematic cross section through a clip chain track 1 having track runway and supporting rails 5, 5', 6, 6' arranged pair-wise on a chain track support 2, above and below the plane 3 in which a clip 4 is mounted. The rails 5, 5', 6, 6' are wire rails of circular cross-section in the embodiment illustrated but they could equally weli be polygonal, oval or of some other shape, as required. The rails are mounted to be longitudinally displaceable in bearings 7, 7', 8, 8' adapted to their cross section (e.g. triangular bearings) which are integral with the support 2.

To hold the rails 5, 5', 6, 6' in their bearings, they are secured by T-shaped clamps 10, 10' which are fixed in the support 2 by screws 9, 9. By means of track and supporting rollers 11, 11', 12, 12' which are arranged pair-wise above and below the plane 3, the clips are carried on those parts, 13, 13', 14, 14' of the rails 5, 5', 6, 6' which are not covered by the bearings 7, 7', 8, 8' or clamps 10, 10', and are thus supported against vertical and horizontal forces acting on them.

These forces act in the direction of the resultant of the weight of the clip and the horizontal force.

Thus the surface of the rollers 11, 1 1', 12, 12' bear against the track surfaces 13, 13', 14, 14' of the rails 5, 5', 6, 6' in this resultant direction (see the two arrows in Figure 1).

Figure 2 is an eniarged section showing a portion of the chain track support 2 and it shows an alternative shape of the surfaces of the rollers 12, 12', which in this case are flat, whereas in Figure 1 they are concave. Where the surface of a roller is concave, it covers substantially completely the exposed arc of the surface of the runway and supporting rail 6, whereas the flat roller surface 12' only meets the surface of the rail 6' at a tangent. The choice of surfaces is optional since it has virtually no influence on the rolling action.

Figure 3 shows part of a lower chain track support in an area of curvature of the clip chain track, showing rails 6, 6' mounted by connecting bars 15. The bars 1 5 situated in the free area hold the rails 6, 6' and have bearing surfaces of the same shape as the bearings 8, 8' integral with the support 2. Holding bars 1 6 of the appropriate size are placed over the rails 6, 6' in the connecting bars 1 5 to hold the rails in position, and these bars 1 6 are fixed by screws 1 7. To compensate for the radius of curvature in the curved regions of the track 1, the connecting bars 1 5 are mounted in recesses 1 8 on the support 2 so that they are displaceable transversely to the direction of movement of the clips 4.

Figure 4 shows a connecting bar 1 5 displaceably mounted in a recess 18 and having bearings 8, 8' carrying the rails 6, 6' which are fixed by T-shaped clamps 10'.

Claims

1. A clip chain track comprising tenter clips carried by rollers running on support rails mounted in a track support, the rollers being arranged to bear against the contact surfaces of the rails, wherein the rails are disposed above and below the mounting plane of the clips, are of small cross section, and are arranged pair-wise to be longitudinally displaceable in bearings shaped to receive them and carried by the track support, the contact surfaces of the rollers being adapted to the shape of the rails for running thereon.

2. A track according to claim 1, wherein the rails are arranged pair-wise in the bearings and are fixed in their position and distance apart by clamps.

3. A track according to claim 2, wherein the clamps are T-shaped.

4. A track according to any preceding claim, wherein the rails are of wire.

5. A track according to any preceding claim, wherein the rails, in regions of deflection and curvature of the track, are supported by connecting bars mounted on the track support so as to be displaceable transversely to the direction of transport of the clips.

6. A track according to claim 4 wherein each wire is of circular cross section.

7. A track according to claim 4 wherein each wire is of Cr-Ni steel.

8. A clip chain track constructed and arranged substantiaily as herein described and shown in the drawings.