GB2561334A

GB2561334A - A Moveable positioning device for a forming press

Info

Publication number: GB2561334A
Application number: GB1702895.2A
Authority: GB
Inventors: Skertchly David
Original assignee: Auxetic Performance Ltd
Current assignee: Auxetic Performance Ltd
Priority date: 2017-02-23
Filing date: 2017-02-23
Publication date: 2018-10-17
Anticipated expiration: 2037-02-23
Also published as: GB201702895D0; GB2561334B

Abstract

A forming press, for applying pressure to a work piece comprises at least one moveable pressure applying component 24, moveable between an open position and a press position, and a positioning device 28 for holding a work piece during pressing. The positioning device may comprise a frame which holds the work such as a composite pre-preg in the frame aperture. The frame may comprise holes 34 which locate on pins 32. The work may be held on the frame by friction and the frame may be textured. The pins 32 may be smaller than the holes 34 to accommodate thermal expansion, and the positioning device may be made of a material of low thermal expansion. The composite may be cured in the press and the press movement may be staged to allow heating of the composite prior to final pressing and further heating in the final pressing stage. The location pins 32 may be used as a press stop or for providing controlled movement of the press to the final press position.

Description

(54) Title of the Invention: A Moveable positioning device for a forming press Abstract Title: Press work location (57) A forming press, for applying pressure to a work piece comprises at least one moveable pressure applying component 24, moveable between an open position and a press position, and a positioning device 28 for holding a work piece during pressing. The positioning device may comprise a frame which holds the work such as a composite pre-preg in the frame aperture. The frame may comprise holes 34 which locate on pins 32. The work may be held on the frame by friction and the frame may be textured. The pins 32 may be smaller than the holes 34 to accommodate thermal expansion, and the positioning device may be made of a material of low thermal expansion. The composite may be cured in the press and the press movement may be staged to allow heating of the composite prior to final pressing and further heating in the final pressing stage. The location pins 32 may be used as a press stop or for providing controlled movement of the press to the final press position.

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A Moveable Positioning Device for a Forming Press

Technical Field

This disclosure relates to a manufacturing system and process for changing the shape or properties of a workpiece by the application of pressure in a forming press, and in particular to such a system for composite materials.

Background

Mass manufacture of metal components by a forming press, also commonly called a machine press or simply a press, is common, particularly in the automotive industry. The material to be shaped or textured, commonly called the workpiece, is placed between a mould or die in the press, and a high pressure is exerted on the workpiece. Typical pressures are in the range of ten to several thousand tonnes of force for metal for automotive body materials, however these pressures can vary greatly depending on the material to be shaped and its composition.

The length of time the pressure is held on the workpiece can vary depending on the material and the desired characteristics of the product. There is a drive in industry to reduce the time taken in manufacture of components, and this includes the preparation and transport time of the components between manufacturing operations.

Presses can have various mechanisms for applying pressure including hydraulic, mechanical and pneumatic systems.

SUMMARY

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

According to an aspect of the present disclosure, there is provided a forming press, for applying pressure to a workpiece, the forming press comprising; at least one moveable pressure applying component, moveable between an open position and a press position, means for receiving a positioning device in an open position, the positioning device arranged to hold a workpiece, wherein; when a positioning device is positioned in the open position the at least one moveable pressure applying component is moveable from the open position to a press position to apply pressure to a workpiece, held by the positioning device.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described, by way of example, with reference to the following drawings, in which:

Figure 1 shows a schematic diagram of an example of a forming press;

Figure 2 shows a schematic diagram of an example of a forming press in an open position;

Figure 3 shows a schematic diagram of an example of a forming press in a press position; Figure 4 shows an example of a press cycle;

Figure 5 shows an example of a press cycle;

Figure 6 shows a schematic diagram of an example of a forming press with an actuator; Figure 7 shows a schematic diagram of an example of a forming press with stops; and Figure 8 shows a schematic diagram of an example of a positioning device.

DETAILED DESCRIPTION

Figure 1 shows an example of a forming press 10. The forming press 10 is for manufacturing or changing features of a workpiece 12. The forming press 10 has at least one moveable pressure applying component 14, moveable between an open position, a closed position and a press position (and other positions as may be required), and a stationary pressure applying component 16. In the open position the pressure applying components 14,16 are spaced apart from one another and the workpiece 12 can be inserted into or removed from the forming press 10. In the closed position, the moveable pressure applying components 14,16 are in contact with the workpiece 12, and in the press position the pressure applying components 14,16 are closest together, for example to give the component its final shape.

Fast and efficient loading and unloading of the workpiece 12 in a forming press 10 before and after the application of pressure can be difficult. Although existing press systems are efficient for metal components (where a border can be left around the piece for handling), there is a need for similarly efficient systems for composite materials.

Referring to Figure 2 a forming press 20 is shown in an open position. The forming press 20 comprises a stationary pressure applying component 22, a moveable pressure applying component 24, and is configured to receive a positioning device when the forming press 20 is in the open position. A workpiece 26, to be formed using the press, is held by the positioning device 28.

The movable pressure applying component may move to a closed position where the pressure applying components 22, 24 have moved together to contact the workpiece 26 but are not applying pressure to significantly deform the workpiece 26. Further movement of the movable pressure applying component 24 applies pressure to the workpiece 26 to form it between the pressure applying components 22, 24. At the position in which the final component is formed, the pressure applying components 22, 24 are in the press position. In pressing processes it may be desired to heat the workpiece 26 before or during the application of pressure, for example to assist in, or accelerate, curing of resins in composite components. One or both of the pressure applying components 22, 24 of the forming press 20 may include heating elements which can be used to heat the workpiece 26.

In the example shown in Figure 2, the means for receiving the positioning device is a pin and hole arrangement, whereby pins 30 & 32 on the forming press 20 align with holes 34 & 36 in the positioning device 28.

Alternatively, pins 30 & 32 may be positioned on the positioning device 28, and holes 34 & 36 may be present in the forming press 20, or a combination of pins and holes on both the positioning device 28 and the forming press 20 may be present. In other embodiments other alignment and securing means may be used, such as, but not limited to, pins, tapers, slots, rails or tracks to align the positioning device and a latch, clip, or other fastening device may be used to secure the positioning device in place in the forming press.

The positioning device 28 holds the workpiece 26 before, during, and after the press process to facilitate handling of the workpiece 26 which can be particularly difficult for composite components.

In the example shown in Figure 2, the positioning device 28 is ring shaped, and is arranged to hold the workpiece 26 in its aperture using holding surface 38, or holdings means on or in the surface 38. The positioning device may be any suitable shape to accommodate the workpiece 38 and to mate with the receiving portion of the forming press. In other examples, the positioning device 38 may be a square plate if the receiving portion of the forming press has a square gap for the positioning device to fill. In the example shown in Figure 2 the workpiece is preferably held by friction in the positioning device. Other methods of holding the workpiece can include tapering the aperture, providing a textured surface to the aperture, creating a step in the aperture or creating a removable flange, step or split in the positioning device, or any combination of these features.

As explained above, the workpiece 26, is positioned in the forming press 20, and is secured in position by the pins 30 & 32 of the forming press 20 mating with the holes 34 & 36 of the positioning device 28. The fit of pins 30, 32 into holes 34, 36 may be defined to allow for an appropriate balance of security of mounting, movement to allow adjustment of the position of workpiece 26 and pressure applying components 22, 24, and thermal expansion. In the shown example the pins are located on one of the pressure applying components, but the mounting arrangement for the positioning device may be formed in any suitable part of the press device.

In the example shown in Figure 2, the forming press 20 can receive the positioning device 28 when it is in the open position and then the moveable pressure applying component 24 can move to be in contact with the workpiece 26 held by the positioning device 28, and apply pressure to the workpiece 26.

There are many advantages of using the positioning device discussed herein. In metal pressing, sheet metal is loaded into a press and blanked (that is, when the workpiece is pressed out from the sheet of metal some waste material is left behind around the border). In composite component manufacture, the workpiece cannot be handled in the same way as when working with metal. The uncured composite material may be too soft to be easily handled and moved in to position. Furthermore, the lay-up of fibres within the composite material may not be appropriate for cutting from a larger sheet. Additionally, uncured composites need pressure or pressure and heat for the material to cure, they cannot simply be pressed from a larger sheet. The positioning device can be thought of as a reusable offcut of the workpiece before it is positioned in the press. A number of positioning devices may be made, to facilitate a production line, to load the tailored blanks before pressing or for removing the consolidated part after pressing. This frees the press for the next pressing operation. This may be necessary for some composite components that require a heating process before pressing, a post curing process after pressing or a cooling period before they can be removed.

Referring again to the example shown in Figure 2, the holding surface 38 of the positioning device 28 may be textured to produce the desired shapes and/or surface features on the workpiece 26. In other examples, the holding surface may be textured or shaped such that it can hold the workpiece, but the workpiece does necessarily conform to the full surface texture or shape of the holding surface until pressure or pressure and heat is applied by the pressure applying components.

In another example, the holding surface may be non-textured, and the desired texturing and finishing of the final product may be applied after the pressing process. For example, regions gripped by the positioning device may be designed to be trimmed from the component after manufacturing.

In the example shown in Figure 2, the workpiece 26 is an uncured composite component. In other examples, the positioning device may hold workpieces made from a range of materials commonly used in press manufacturing. These include, but are not limited to, metals, alloys, resins, plastics, composites, and any other material that can be pressed in a forming press.

In the example shown in Figure 3, the forming press 20 of Figure 2 is shown in the press position. In this position, moveable pressure applying component 24 and stationary pressure applying component 22 are closest together to form the final shape of the component 26.

An example press cycle using the forming press 20, the positioning device 28 and the workpiece 26 of Figure 2, is shown in Figure 4. In this example the workpiece 26 is an uncured composite. The forming press 20 starts in the open position, as it is in Figure 2, and point 40 in Figure 4. The positioning device 28 is positioned between the pressure applying components of the forming press 20, and secured in place by aligning the pins 30 and 32 and holes 34 and 36. The moveable pressure applying component 24 is brought down until it comes in contact with the workpiece 26, this is point 42 in Figure 5, and the forming press 20 is now in the closed position in which no force, or a small amount is applied. Heat is applied by components 22 and 24 to the workpiece 26 for a first time period, raising the temperature of the workpiece 26 to a temperature in the range of 150-250°C. After this first time period, at point 44 in Figure 5, the moveable pressure applying component 24 is brought down to its lowest position, the press position, that of Figure 3, and point 46 in Figure 5, during this movement the pressure applied to the workpiece is increased to a pressure in excess of 5MPa, over a period of 200 to 400ms. The pressure is held for a second time period and at the end of this time period, point 48 in Figure 5, the moveable pressure applying component 24 is retracted to the open position again, and the positioning device 28 and workpiece 26 may be removed from the forming press 20.

Another example press cycle is shown in Figure 5, where the workpiece 26 of Figure 2 is an uncured composite comprising pre-preg fibres and liquid resin. The workpiece 26 is held in the positioning device 28 which is received by the forming press 20. The forming press starts in the open position, point 50 in Figure 5. The moveable pressure applying component 24 is brought down until it comes in contact with the workpiece 26, this is point 52 - the forming press is now in the closed position. A first pressure and heat are applied to the workpiece 26 raising the temperature of the workpiece to a temperature in the range of 150-250°C over a first time period. Point 54 is at the end of this first time period. A second pressure in excess of 5MPa is then applied to the workpiece 26, wherein the pressure is increased over a second time period of 200 to 400ms. Point 56 is at the end of this second time period. The moveable pressure applying component 24 is held on the workpiece 26, continuing to apply the second pressure, for a third time period until point 58, before being retracted to point 60, where the forming press 20 is in the open position, and the positioning device 28 can be removed. This press cycle facilitates the infusion of liquid resins into dry tailored blanks in the press in the first time period, before the higher pressure is applied.

In the example shown in Figure 6, an actuator 62 controls the application of pressure by a forming press 64 comprising moveable pressure applying component 66, stationary pressure applying component 68, positioning device 70 and workpiece 72. This actuator may be stand alone or may be incorporated into the forming press as alignment means for aligning the positioning device in the forming press. In Figure 6 the actuator controls pin 74 that aligns with hole 76 of the positioning device 70. In Figure 6 the actuator 62 is used to control the position of the moveable pressure applying component 66 so that different positions and rates of change of position may be applied for different time periods. The press cycle of Figure 5 for example may be achievable when an actuator is used in the forming press. The actuator is useful when using a simple forming press which has poor control of the position of the pressure applying component 66.

In another example shown in Figure 7, the pins previously described for aligning and securing the positioning device are fixed non-retractable pins 78 incorporated into the forming press to control the thickness of the workpiece during manufacture. Alternatively, the fixed non-retractable pins 78 may be positioned on the moveable pressure applying component 24.

The positioning device may be reusable in the same forming press, or in other forming presses or manufacturing processes, or it may be a single use, disposable device. If the positioning device is cold and the pressure applying component is hot, if the positioning device is made from the same material as the pressure applying component there will be a gap created between the positioning device and the pressure applying component as the positioning device heats up, which will result in a line of flash around the final component. This flash can be minimised by making the positioning device from a thermally stable material such as invar or Carbon fibre and the hole 38 sized to be a tight fit on the pins 30 and 32 at the proposed operating temperature.

In an example shown in Figure 8, a composite tailored blank 80 for use in the presses described above is made in a positioning device 82 with the use of a die 84. In the example shown, the composite tailored blank 80 can be made in the positioning device 82 and the positioning device 82 can then be easily transported to a press for curing of the blank or other pressing process. In some examples the tailored blank may comprise layers of reinforcement and/or a liquid resin matrix and/or a resin film.

In another example, edges of the moveable pressure applying component 24 and/or the positioning device 28 may be sharp and the moveable pressure applying component 24 and the positioning device 28 may have a tight tolerance when the moveable pressure applying component 24 is in the press position. In this example, the sharp edges may shear the workpiece allowing blanking of the workpiece 26.

Described above is a forming press comprising at least one moveable pressure applying component, moveable between an open position and a press position and a means for receiving a positioning device. The forming press may be any configuration of forming press known to those skilled in the art of production engineering. The examples described herein are vertical forming presses, however it is obvious that the methods and apparatus disclosed herein are just as applicable to any form of manufacturing press, such as, but not limited to, horizontal, pneumatic or mechanical presses.

In the described example only one pressure applying component is moveable, but as will be apparent from the terms of the description, both components may be moveable, or presses with more than two pressure applying components may be utilised, with any number of those moveable.

Claims

1. A forming press, for applying pressure to a workpiece, the forming press comprising;

at least one moveable pressure applying component, moveable between an open position and a press position, means for receiving a positioning device for holding a workpiece, wherein; the at least one moveable pressure applying component is moveable from the open position to the press position to apply pressure to a workpiece held by a positioning device received by the means for receiving.

2. The forming press of claim 1, wherein the workpiece is a composite material.

3. The forming press of claim 1 or 2, wherein the positioning device comprises a holding surface, wherein the holding surface is textured to produce desired shapes and/or surface features on the workpiece and optionally to retain the workpiece.

4. The forming press of any of claims 1 to 3, further comprising alignment means suitably arranged to align the positioning device in the forming press.

5. The forming press of claim 4, wherein the alignment means is a pin and hole configuration.

6. The forming press of claim 5, wherein at least one pin is suitably smaller than the hole which it mates with to allow thermal expansion of the workpiece.

7. The forming press of any of claims 1 to 6, further comprising at least one fixed nonretractable pin to control the workpiece thickness.

8. The forming press of any of claims 1 to 7, wherein the positioning device is reusable in a manufacturing process.

9. The forming press of any of claims 1 to 8, wherein the positioning device is made from a material with a low coefficient of thermal expansion.

10. The forming press of any of claims 1 to 9, wherein the at least one moveable pressure applying component comprises sharp edges and/or the positioning device comprises sharp edges, and there is a tight tolerance between the at least one moveable pressure applying component and the positioning device.

11. A method of fabricating a composite component in the forming press of any of claims 1 to 10, the method comprising the steps of:

positioning an uncured composite workpiece in the positioning device, positioning the positioning device in the means for receiving of the forming press, heating the workpiece to a temperature in the range of 150-250’C, and then applying a pressure to the workpiece which pressure is increased from a starting pressure to a pressure in excess of 5MPa, wherein the pressure is increased to in excess of 5MPa over a time period of 200 to 450ms.

12. A method of fabricating a composite component in the forming press of any of claims 1 to 10, the method comprising the steps of:

positioning an uncured composite workpiece in the positioning device, positioning the positioning device in the means for receiving of the forming press, applying a first pressure for a first time period and heating the workpiece to a temperature in the range of 150-25CTC over that first time period, and applying a second pressure in excess of 5MPa to the workpiece, wherein the pressure is increased from the first pressure to a second pressure in excess of 5MPa over a second time period of 200 to 450ms.

13. The method of claim 12 wherein the uncured composite workpiece comprises pre-preg fibres and liquid resin.

14. A method of fabricating a composite component in the forming press of any of claims 1 to 10, the method comprising, producing a composite blank in the positioning device, positioning the positioning device and composite blank in the forming press.

15. The method of claim 14, wherein the composite blank comprises a liquid resin matrix.

16. The method of claim 14, wherein the composite blank comprises a resin film.

17. The method of claim 14, wherein the composite blank comprises layers of reinforcement.

18. The method of claim 14, wherein a die is used in conjunction with the positioning device to produce the composite blank.

Intellectual

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Application No: GB1702895.2 Examiner: Tim James