GRIPPER BAR BODY FOR A GRIPPER CARRIAGE ARRANGEMENT

Abstract

The invention relates to a gripper bar body for a gripper bar in a gripper carriage arrangement in a machine for treating sheet material, the gripper bar body being configured to carry gripper brackets for movement between sheet gripping and sheet releasing positions. The gripper bar body is formed as a hollow structure comprising at least two different materials, the two different materials comprising at least a metal material and a composite material and the at least two different materials being at least partly arranged in a superposed manner. The resulting bar has a better resistance to wear than the ones of the state-of-the-art.

Claims

1. A gripper bar body for a gripper bar for gripping sheet material, the gripper bar body being configured to carry gripper brackets for movement between sheet gripping and sheet releasing positions, the gripper bar body comprising: a substantially hollow structure comprising at least two different materials, wherein the at least two different materials include at least a metal material and a composite material, the at least two different materials are at least partly arranged in a superposed manner, and an abrasion resistance of the composite material is larger than an abrasion resistance of the metal material.

2. The gripper bar body of claim 1, wherein the gripper bar body includes at least two areas of superposed materials.

3. The gripper bar body of claim 2, wherein the at least two areas of superposed materials are at least in substantially in opposing areas of the substantially hollow structure.

4. The gripper bar body of claim 2, wherein the at least two areas of superposed materials extend substantially along an entire width of the gripper bar body.

5. The gripper bar body of claim 2, wherein areas for engaging the gripper bar body are separate from the at least two areas of superposed materials.

6. The gripper bar body of claim 1, wherein the metal material comprises at least one of aluminum, magnesium and/or titanium.

7. The gripper bar body of claim 1, wherein the composite material comprises at least a fiber composite material.

8. The gripper bar body of claim 7, wherein the fiber composite material comprises aramid fiber reinforced.

9. The gripper bar body of claim 7, wherein the fiber composite material comprises at least one of carbon fiber reinforced plastic, glass fiber reinforced plastic, natural fiber reinforced plastic, and/or wood fiber reinforced plastic.

10. The gripper bar body of claim 7, wherein fibers of the fiber composite material are arranged substantially in a direction parallel a length of the gripper bar body.

11. The gripper bar body of claim 7, wherein fibers of the fiber composite material are arranged in at least two directions.

12. The gripper bar body of claim 7, wherein the composite material is a coating, the coating having one or several layers, the one or several layers having a total thickness of less than 0.5 mm.

13. The gripper bar body of claim 2, wherein the substantially hollow structure is a substantially quadrangular shaped structure with rounded angles, and the at least two areas comprise parts of longitudinal areas of the substantially quadrangular shaped structure.

14. The gripper bar body of claim 1, whereas the composite material is attached to the metal material by gluing.

15. A gripper carriage arrangement comprising a gripper bar body according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention will now be explained with reference to several embodiments, which are shown in the attached drawings. In the drawings,

[0028] FIG. 1 shows a three-dimensional view of a gripper bar body according to a preferred embodiment of the invention;

[0029] FIG. 2 shows a cross section of a gripper bar body according to a preferred embodiment of the invention;

[0030] FIG. 3 a and b shows different three-dimensional views of a gripper bar according to a preferred embodiment of the invention; and

DETAILED DESCRIPTION OF POSSIBLE EMBODIMENTS OF THE INVENTION

[0031] This section describes in details some possible variations for implementing the invention followed by specific examples of embodiments.

[0032] In FIG. 1 a three-dimensional view of a gripper bar body (1) according to a preferred embodiment of the invention is shown. FIG. 2 shows a cross-section thereof. The bar body is configured to carry gripper brackets, which might be engaged with the gripper bar body at predefined positions (2) for movement between sheet gripping and sheet releasing positions. According to this preferred embodiment, the gripper bar body is formed as an entirely hollow structure. According to the embodiment of the invention presented in FIGS. 1 and 2, the hollow structure of the gripper bar body (1) is a substantially quadrangular shaped structure with rounded angles.

[0033] In FIG. 3 a) and b) it is well visible that the gripper bar body comprises two different materials. According to the preferred embodiment shown in FIG. 3 the materials comprise a metal material (4) and a composite material (3) and the at least two different materials being at least partly arranged in a superposed manner. In the shown embodiment, the hollow structure is built by a metal material (4), and in certain areas, a composite material (3) is attached on the metal material.

[0034] As can be seen in particular in FIG. 3b), the gripper bar body (1) comprises two areas of superposed materials.

[0035] According to a preferred embodiment of the invention the gripper bar body (1) is formed of Aluminum and/or Magnesium and then predefined areas are coated with aramid fiber material with a thickness of approximately 0.4 mm. Preferably this is provided by 2 layers of aramid fiber material of a thickness of 0.2 mm. The aramid fiber material is connected by gluing the two materials together, preferably by void of air. A well known example of aramid is known commercially under the name “Kevlar”.

[0036] When using a thickness of composite material smaller than 0.5 mm, fixated above the metal, the main effect observed is an improvement of the abrasion resistance of the bar (independent from the fact that the materials cover one or more areas or the metal), with a minor increase in weight. The increase of the stiffness of the bar is a minor (and positive) side-effect (barely measurable with a 0.2 mm thickness). A thicker layer of the composite material is advised to obtain a significant increase in the stiffness of the bar.

[0037] The abrasion resistance can be measured by measuring the loss of mass of the bar when exposed to a repeated scratching action. As an example, aramid fibers material has a better abrasion resistance than aluminum or magnesium.

[0038] Another positive side effect obtained by using an aramid-based composite material on the gripper bar is the ability to keep the bar in one piece in case of a catastrophic failure. This is enabled by the ability of the aramid fibers to absorb and dissipate the energy thanks to the combination of fibers having high stiffness and both high ultimate tensile and strain strength. It prevents the ejection of pieces of the bar that might be either ejected from the machine and hurt someone or causing serious damage to the machine due to the multiplication of the ejected parts.

[0039] The two areas showing the Aramid fiber material in FIG. 3b) are located at two in particular opposing areas of the hollow structure of gripper bar body (1) and substantially along the entire length.

[0040] Since we do not use the composite material to rigidify the bar, but for protection against hits or scratches, we do not need the composite material all around the bar, thereby gaining in production cost, complexity and production yield (even if by putting the composite material in several areas achieved positive results in rigidity).

[0041] The gripper bar body, according to the shown embodiment, also comprises areas for engaging the gripper bar body (5). His can be an engagement with other parts lie for example brackets etc. or the machine, where the gripper bar will be connected to. Preferably these areas (5) are omitted from superposing the composite material. Having the metal material in the engaging area facilitates the engagement, for example, by mechanical means, like screws, etc.