EP-4739490-A1 - METHOD FOR REMOVING A FOIL OR TAPE FROM AN INNER SURFACE OF A MOLD AND APPARATUS

Abstract

A method for removing a foil (17) or tape (46) from an inner surface (14) of a mold (7) for casting a wind turbine blade (3) or a part thereof, the foil (17) or tape (46) comprising a non-stick material (18) on the inside which is configured not to react with resin during casting (S1, S2, S3), and an adhesive material (19) on the outside to stick to the inner surface (14) of the mold (7), the method comprising: a) locally heating (S5) the foil (17) or tape (46) to soften the adhesive material (19); and b) exerting (S6) a pulling force on the foil (17) or tape (46) to remove the foil (17) or tape (46) from the inner surface (14) of the mold (7). By way of locally heating the foil or tape, it is no more required to rely on the remaining heat of the mold after removal of the cast wind turbine blade. This has ergonomic advantages and makes the process more flexible.

Inventors

• HARBOE, NIELS

Assignees

• Siemens Gamesa Renewable Energy A/S

Dates

Publication Date

20260513

Application Date

20240814

Claims (1)

1. Patent claims 1. A method for removing a foil (17) or tape (46) from an inner surface (14) of a mold (7) for casting a wind turbine blade (3) or a part thereof, the foil (17) or tape (46) com- prising a non-stick material (18) on the inside which is con- figured not to react with resin during casting (SI, S2, S3), and an adhesive material (19) on the outside to stick to the inner surface (14) of the mold (7), the method comprising: a) locally heating (S5) the foil (17) or tape (46) to soften the adhesive material (19); and b) exerting (S6) a pulling force on the foil (17) or tape (46) to remove the foil (17) or tape (46) from the inner surface (14) of the mold (7). 2. The method according to claim 1, wherein the temperature of the foil (17) or tape (46) during step a) is controlled to exceed 60 degrees Celsius. 3. The method according to claim 2, wherein the temperature is controlled using a temperature sensor (25) sensing the temperature of the foil (17) or tape (46). 4. The method according to one of claims 1 - 3, wherein heat (27) is applied in step a) using a heat source (26) arranged on the inside of the mold (7). 5. The method according to claim 4, wherein the heat source (26) is moved inside of the mold (7) during, before and/or after step a). 6. The method according to claim 4 or 5, wherein a distance (d) between the heat source (26) and the foil (17) or tape (46) is constant during step a). 7. The method according to one of claims 4 - 6, wherein the heat source (26) is a irradiation source, in particular an infrared light source. 8. The method according to one of claims 4 - 7, wherein the heat source (26) is part of a hand-held and/or hand-operated tool. 9. The method according to one of claims 4 - 8, wherein a surface area (24) of the foil (17) or tape (46) heated in step a) is smaller than 1 m 2 when a position of the heat source (26) is constant. 10. An apparatus (23) for use in the removal of a foil (17) or tape (46) from an inner surface (14) of a mold (7) for casting a wind turbine blade (3) or a part thereof, the foil (17) or tape (46) comprising a non-stick material (18) on the inside which is configured not to react with resin during casting (SI, S2, S3), and an adhesive material (19) on the outside to stick to the inner surface (14) of the mold (7), the apparatus (23) being configured for locally heating the foil (17) or tape (46) to soften the adhesive material (19). 11. The apparatus according to claim 10, comprising control circuitry (37) to control the temperature of the foil (17) or tape (46) to exceed 60 degrees Celsius. 12. The apparatus according to claim 10 or 11, comprising a heat source (26) which is movable inside the mold (7). 13. The apparatus according to claim 12, comprising a frame (30, 31) for keeping a distance (d) between the heat source (26) and the foil (17) or tape (46) constant. 14. The apparatus according to claim 12 or 13, comprising: a reflector (28) for reflecting heat (27) onto the foil (17) or tape (46), the reflector (28) being mounted on the frame (30, 31), an irradiation source (26) as a heat source mounted in front of the reflector (28) so as to face the foil (17) or tape (46), at least two wheels (32) carrying the frame (30, 31), and/or a pole (33) mounted to the frame (30, 31) or reflector (28) for steering the apparatus (23) along the inside of the mold (7). 15. The apparatus according to one of claims 10 - 14, which is configured as a hand-held and/or hand-operated tool.

Description

Description Method for removing a foil or tape from an inner surface of a mold and apparatus The present invention relates to a method for removing a foil or tape from an inner surface of a mold and to an apparatus. One way to produce more power using a wind turbine under giv- en wind conditions is to increase the size of the blades. However, the manufacture of wind turbine blades is becoming increasingly difficult for increasing blade sizes. Currently, many wind turbine blades are made by pre- manufacturing parts of the blade separately, such as a pres- sure-side shell and a suction-side shell, and gluing the parts to each other. The parts are, for example, pre- manufactured inside a mold by infusing a fiber lay-up with a resin and curing the resin. In another method, disclosed in EP 1310 351 Al, the blade is manufactured by packing a fiber lay-up for the entire blade, or for a lengthwise blade section, on a mandrel (mold core) and by infusing resin in a vacuum-assisted manner, and curing the resin inside a mold. Hence, when producing large composite structures, such as blades or parts thereof, there is a need for a large mold. Such molds are typically themselves made of fiber composite materials. The reason is that this gives a lot of freedom with regard to the shape of the mold surface. Further, such molds are lightweight. However, the mold surface must be protected to ensure that a molded part, which is also made of a fiber composite materi- al, can be demolded from the mold. To this end, the mold sur- face is covered according to one approach known in the art, with a self-adhesive PTFE (polytetrafluorethylene)-foil. The adhesive material used in such foils is often silicone-based in order to withstand high temperatures during the curing phase. Worn out or otherwise damaged foils need to be replaced. It is known to pull off or tear off worn-out foils from the mold surface. If this pulling or tearing off is not done at ele- vated temperatures, the pulling force is high, with the sili- cone-based adhesive clinging to the mold surface. This may induce damages to the mold surface, in particular, if filler material, paint or even fibers are torn out of the mold sur- face along with the foil. It is thus common practice to remove the worn-out foil while the mold is still hot after the demolding of the part. In particular, if the resin used in the molding of the part has a polymer matrix with an exothermic crosslinking, one can still benefit from the resulting heat. The heat keeps the ad- hesive of the foil soft, which may therefore be removed more easily. However, working in a hot-mold shell is a very challenging working environment to human operators. Depending on the size of the blade, the operator may be able to stand fully within the mold shell. The mold shell, right after demolding, typi- cally has a temperature between 60 and 80 degrees Celsius. This puts significant heat loads on the human operator. This is especially the case, when the human operator needs to ex- ert substantial forces to pull off the foil from the mold surface. Also, the heat remaining in the mold may not always suffice, so the worn foil needs to be cut into narrow strips to enable the pulling or tearing off of the foil as the pulling force may otherwise become too high for a human operator. Also, when the adhesive has cooled down too much, spatulas may be necessary to scrape off the adhesive remaining stuck to the mold surface of the removal of the foil. This scraping off may introduce scratches and marks on the delicate mold sur- face. It is thus one object of the present invention to provide an improved approach towards removing a foil or tape from an in- ner surface of a mold. According to a first aspect, there is provided a method for removing a foil or tape from an inner surface of a mold for casting a wind turbine blade or a part thereof, the foil or tape comprising a non-stick material on the inside which is configured not to react with resin during casting, and an ad- hesive material on the outside to stick to the inner surface of the mold, the method comprising: a) locally heating the foil or tape to soften the ad- hesive material; and b) exerting a pulling force on the foil or tape to re- move the foil or tape from the inner surface of the mold. Applying the present method, the adhesive material may be lo- cally heated to remove the foil or tape. Therefore, one does not need to rely on the remaining heat after casting the wind turbine blade or a part thereof to ensure sufficient softness of the adhesive material. Thus, the removal of the foil or tape may be done after the mold has sufficiently cooled down to allow for an ergonomic working environment. Another ad- vantage of the present method is that it provides more flexi- bility with regard to the processes around the mold. Removal of the foil or tape may thus be postponed to a point in time which allows for a more efficient use of the mold. The non-stick material may