MXPA97004071A - Method and pressing device to manufacture unse - Google Patents

Abstract

One method for manufacturing a seal on a cylinder head of a vehicle engine includes providing a bearing groove in a cylinder head of a vehicle engine and providing a mold member to cooperate with the bearing groove to form the seal. . The seal material is introduced into the mold member to provide a defined excess that exceeds the volume of seal material required to fill the bearing groove. The curing of the seal material contained in the bearing groove and the mold member is achieved under pressure. The pressing device for carrying out the method includes a mold member with a receiving groove for cooperation with the bearing groove of the cylinder groove

Description

METHOD AND PRESSING DEVICE FOR MANUFACTURING A SEAL BACKGROUND OF THE INVENTION The present invention relates to a method for manufacturing a seal in a shaped body, especially in the cylinder head of a vehicle engine, in which the cylinder head is a die-cast member and has a transport slot for receiving the seal and in which the seal is applied under pressure and also relates to a pressing device for applying a seal to the shaped body, especially a cylinder head of a vehicle engine in which the head of the cylinder comprises a groove of bearing for the seal. It is known to apply a seal, for example in a cylinder head consisting of a member emptied with a motor vehicle matrix by application with a cartridge gun or any other device for applying the seal material, for example silicone elastomer in the bearing groove of the cylinder head under high pressure to anchor the seal as safely as possible inside the bearing groove.

From German Patent 30 18 074 it is known to apply a seal of silicone elastomer in one or more layers, to allow the solvent to evaporate at room temperature and in this way effect the sealing cure. The problem with such seals is that for a manufacturing speed required for example as is necessary in the automotive industry, bubbles will form inside the seal, which destroys the sealing properties of the seal. In this way, it is known to apply considerable pressures, for example a pressure of 60 bar. Such pressure, however, requires not only a correspondingly stable support of the cylinder head gasket, which consists of a sheet metal formed or preferably also consists of a die-cast member. The high-pressure pressing device required for the application of the seal is also very expensive and complicated, especially since the application must be automated. All the joints, etc., of the application arm in this way must withstand high pressure so that, however, the precision of the shape can not be neglected. In addition it is known to produce the seal as an extruded profile, so that numerous forms for the design of the seal have come to be known. For example, such seals are known from German Patent 24 37 567 and German Patent 25 51 360. The material to be used is selected such that it is substantially resistant in the presence of oil as well as in the presence of acid components that are contained within the old oil. However, hot oils and this low viscosity form have the tendency to slip under the seals especially when the cylinder heads emptied with matrix are being used, which generally have a rough surface substantially greater than the sheet covers of metal. It is therefore an object of the present invention to provide a method for manufacturing a seal in a shaped body as well as a pressing device with which a permanent seal action still with respect to low viscosity oil and shaped bodies Die-casting is provided by what, however, manufacturing should require only little expense although at the same time, specifications related to the required pressure and accuracy must be maintained.

BRIEF DESCRIPTION OF THE INVENTION The inventive method for manufacturing a seal in a shaped body such as a cylinder head of a vehicle engine in accordance with the present invention is mainly characterized by the following steps: Provide a bearing groove in the cylinder head; Providing a mold member to cooperate with the bearing groove to form the seal; Introduce the seal material in the mold member to provide a defined excess to overcome the volume of the sealing material required to fill the bearing groove; Cure under pressure the seal material contained in the bearing groove and the mold member to form the seal. Preferably, the introduction step includes the step of pressing the defined excess, while being in a plastically deformable state before the curing step in the bearing groove. Preferably, the introduction step includes the step of applying pressure of 1.5 to 6 bar on the seal material during the introduction. The pressure is preferably 3 bar. Advantageously, the introduction step includes the step of applying the seal material with a low pressure metering and mixing device and the sealing material is preferably a heat curable two component silicone elastomer.

Advantageously, the method further includes the step of heating the seal material before introducing it into the mold member and / or the step of heating the cylinder head before introducing the material of the cylinder and / or the step of heating the cylinder. mold member before introducing the seal material. Advantageously, mold member has low mass and comprises a receiving groove, in which the mold member is hardened in the area of the receiving groove. Preferably, the method further comprises the step of providing the receiving groove with a non-tacky surface layer to facilitate removal of the seal from the mold member. Preferably, the non-tacky surface is made of polytetrafluoroethylene. Advantageously, the seal material is without solvent, especially free of ethyl acetate. The pressing device according to the present invention for applying a seal to a shaped body such as a cylinder head of a vehicle engine, wherein the shaped body or cylinder head comprises a bearing groove for receiving the seal , is characterized primarily by: A mold member with a receiving groove for receiving the seal material in an amount that provides a defined excess that exceeds the volume of the seal material required to fill the bearing groove, in which the device of pressing press the excess defined in the bearing groove and in which the mold member and the bearing groove cooperate to enclose the seal material to be cured therein under heat. Advantageously, the mold member is positioned in such a way that the receiving groove faces upwards and the stamp material is inserted into the receiving groove from above. Preferably, the pressing device further comprises a heating device for cyclically heating at least one of the cylinder head and the mold member to a preheating temperature and a curing temperature and further comprising a preheating zone for preheating the cylinder head in advance to the pressing device. Preferably, the preheating temperature is about 60 ° C and the cure temperature is about 150 ° C. Surprisingly, with the inventive solution, the seal introduced into the bearing groove of the shaped body is free of bubbles and also prevents the oil from sliding under the seal, without requiring high pressure application during curing. By applying the seal first in the receiving groove of the mold member, it is ensured that on the active surface of the seal, which will subsequently be placed on the head of the cylinder or any other counter-surface of the shaped body, no bubbles will occur. In general, the bubbles will not form during low pressure application at the base or at least the direction will move upwards, ie, outside the area of the active surface of the seal. By pressing the seal material between the shaped body (for example, the cylinder head) and the mold member, the bubbles are removed. In general, however, the formation of bubbles at the base of the bearing groove would be essentially non-critical as it would be completely surrounded by the seal material. Apparently, the seal material during pressing between the mold member and the shaped body experiences an intense bond with the surrounding material, i.e., especially with the die cast member, such that the oil slip between the seal and the slot is safely avoided. In contrast to the high pressure method for applying the seal directly in its own in the bearing groove, the inventive method has the advantage that considerably reduced pressure can be applied. Surprisingly, especially high pressure is not required to press the mold member onto the shaped body. Nevertheless, it is understood that adequate conditions must be met for the healing stage. In this context, within a special modality, it was suggested to heat cure the seal, especially at a temperature of approximately 150 ° C. The defined excess, which fills the bearing groove and provides additional material in relation to the size of the bearing groove, provides a sufficient margin of safety for the complete filling of the bearing groove, so it is understood that during the Curing is preferred that there is no contraction of the material. Especially preferred is a two-component, heat resistant silicone elastomer, which provides the required mechanical properties and also excellent recovery performance. It is especially advantageous that with the inventive solution a shaped body such as a die-cast member including the seal, can be prefabricated and for example, supplied to the engine manufacturer in a prefabricated condition.

BRIEF DESCRIPTION OF THE DRAWINGS The object and advantages of the present invention will appear more clearly from the following specification together with the accompanying drawings, in which: Figure 1 shows a sectional view of a seal applied to the mold member for use with a first embodiment of the method inventive; Figure 2 shows the seal of Figure 1 after the pressing step between the mold member and the shaped body, the step of curing and removal; Figure 3 shows a schematic representation of the application of the seal material within the receiving slot of the mold member in another embodiment of the invention; and Figure 4 shows the seal introduced into the receiving slot of the mold member of Figure 3 before placing the shaped body.

DESCRIPTION OF THE PREFERRED MODALITIES The present invention will now be described in detail with the aid of several specific embodiments using Figures 1 to 4.

Figure 1 shows the manner in which the inventive seal 10 is applied to the mold member 12. The mold member 12 has a receiving groove 14, which comprises the base 16, the flanks of the groove 18 and the surfaces side 20 with a non-tacky layer 22 extending over all surfaces. The non-tacky layer 22 allows easy removal of the seal from the mold member and is non-sticky in relation to the seal material 10, for example a silicone elastomer. The seal 10 is introduced at room temperature (about 20 ° C) inside the receiving slot 14 of the mold member, whereby the excess material 24 projects considerably upwards to pass to the side surfaces 20. The excess material 24 is of such an amount that it fills completely the bearing groove 26, which is indicated by a dotted line in Figure 1. Accordingly, the sum of the surfaces 28 is substantially greater than the surface 30 so the ratio of the surfaces in relation to one another it can be calculated or, advantageously, determined empirically. It is understood that any other suitable forms of excess material 24 are possible. It is preferred to allow simple fabrication with low pressure application devices, by which is meant that the temperature for preheating is selected such that the seal material for the seal 10 is sufficiently viscous to be produced completely within the groove. 26. Directly after the application of the seal material (10) within the receiving slot 14, the heating device (not shown) is turned on to increase the temperature to such an extent that healing begins. At the same time, the shaped body 32 shown in Figure 2 is then placed in the mold member 12 and by the application of pressure of those parts, the excess amount of material 24 is deformed, in such a way that the seal 10 assumes the shape required in the area of the bearing groove 26. Since the surface 30 is a little smaller than the surface 28, the excess seal material of the seal 10 is forced out laterally. It is not critical if this material remains in the shaped body 32, since it does not interfere with the actual seal function. However, it is understood that the material, if required, can be eliminated by suitable means. The temperature of the unit consisting of the shaped body 32 and the mold member 12 is maintained at the curing temperature as required to cure the seal 10. For example, this takes 1 to 2 minutes. In this context, it is favorable to achieve good duty cycle times when the heating of the mold member and the shaped body has already started as soon as the seal material for the seal 10 is brought to the state shown in Figure 1. In this context is favorable when the mold member 12 has a comparatively minimal heat capacity, for example, is a hollow profile, which is supported only in the area of the receiving slot 14 to be able to withstand the applied pressure. In this context, it is especially favorable that there is no high pressure, but only low pressure application is required to manufacture the seal. Accordingly, the load specifications for the support of the shaped body 32, for example, in the form of a cylinder head, as well as also for the mold member 12 are substantially reduced. Another embodiment of the inventive solution is represented in Figures 3 and 4. Although the shape of the seal 10 according to Figures 1 and 2 can be introduced substantially in bubbles, so the especially low number of bubbles in the area of the Active surface 34 is important, the embodiment according to Figures 3 and 4 of mold member 14 is even more favorable with respect to avoiding bubbles at high seal material application rates despite the low pressure. The application nozzle 36 as part of a low pressure application device introduces the seal material for the seal 10 from above into the receiving slot 14. The base 16 of the groove 14 has a special design, which achieves a particularly favorable flow deflection of the introduced seal material. As can be seen in relation to the arrows 38, 40 shown in Figure 3, the seal material is laterally bent by the front tip 42 and flows along the surfaces of the base 16 of the slot 14 and the surfaces of the edges. adjacent flanks 18 to fill the entire area of the receiving slot 14. In this way, there results the shape of the seal 10 shown in Figure 4 before placing the shaped body 32 on the mold member 12. It is understood that the application nozzle 36 can be aligned in a suitable manner. In the embodiment shown, it is suggested to select an alignment, which is perpendicular to the plane of the drawing so that if desired, a slope transverse to the plane of the drawing, can also be applied to facilitate the flow of the viscous seal material 10 out of the nozzle. This embodiment is especially suitable for rapid formation of a seal 10 without bubbles. It is understood that it is in a particularly favorable inventive manner that in general, no special protective gas atmosphere should be provided, since it is preferred to use a solvent-free seal material which may, for example, be a two-component seal material. Instead of the represented shape of the excess material 24, it is also possible to make the excess material 24 with the application of the nozzle 36 in a manner known per se, in such a way that it is very similar to the desired shape of the groove. bearing 26. In this case, it is necessary to select a special shape of the nozzle depending on the shape of the bearing groove; however, the required material displacement is minimal so that in essence, it is possible to manufacture at a higher speed. The present invention, of course, is not restricted to the specific description of the specification in the drawings, but also encompasses any of the modifications within the scope of the appended claims.

Claims (21)

1. A method for manufacturing a seal on a cylinder head of a vehicle engine, the method is characterized in that it comprises the steps of: providing a bearing groove in the head of the cylinder; providing a mold member to cooperate with the bearing groove to form the seal; introducing the seal material into the mold member to provide a defined excess that exceeds the volume of the seal material required to fill the bearing groove; curing under pressure the seal material contained in the bearing groove and the mold member to form the seal.
2. 2. The method according to claim 1, characterized in that the introduction step includes the step of pressing the defined excess, while in a plastically deformable state before the healing step, into the bearing groove.
3. 3. The method according to claim 1, characterized in that the step of introduction includes the step of applying pressure of 1.5 to 6 bar on the seal material during the introduction.
4. 4. The method according to claim 3, characterized in that the pressure is 3 bar.
5. 5. The method according to claim 1, characterized in that the introduction step includes the step of applying the seal material with a low pressure measuring and mixing device and wherein the seal material is a two component silicone elastomer , heat curable.
6. 6. The method according to claim 1, further characterized in that it includes the step of heating the seal material before introducing it into the mold member.
7. 7. The method according to claim 6, further characterized in that it includes the step of heating the cylinder head before the introduction of the seal material.
8. 8. The method according to claim 7, further characterized in that it includes the step of heating the mold member before introducing the seal material.
9. 9. The method according to claim 6, further characterized in that it includes the step of heating the mold member before introducing the seal material.
10. 10. The method according to claim 1, further characterized in that it includes the step of heating the cylinder head before introducing the seal material.
11. 11. The method according to claim 10, further characterized in that it includes the step of heating the mold member before introducing the seal material.
12. 12. The method according to claim 1, further characterized in that it includes the step of heating the mold member before introducing the seal material.
13. 13. The method according to claim 1, characterized in that the mold member has a low mass and comprises a receiving groove, in which the mold member is hardened in the area of the receiving groove.
14. 14. The method in accordance with the claim 13, further characterized in that it comprises the step of providing the receiving groove with a non-tacky surface layer to facilitate removal of the seal from the mold member.
15. 15. The method in accordance with the claim 14, characterized in that the non-tacky surface is made of polytetrafluoroethylene.
16. 16. The method in accordance with the claim 1, characterized in that the seal material is without solvent.
17. 17. The method according to claim 16, characterized in that the seal material is free of ethyl acetate.
18. 18. A pressing device for applying a seal to a cylinder head of a vehicle engine, in which the head of the cylinder comprises a bearing groove for receiving the seal, the pressing device is characterized in that it comprises: a mold member with a receiving groove for receiving the seal material in an amount that provides a defined excess that exceeds the volume of seal material required to fill the bearing groove, in which the pressing device presses the excess defined in the bearing groove and wherein the mold member and bearing groove cooperate to enclose the seal material to be cured therein under heat.
19. 19. The pressing device according to claim 18, characterized in that the mold member is positioned in such a way that the receiving groove faces upwards and in which the seal material is inserted into the receiving groove from above.
20. 20. The pressing device according to claim 18, further characterized by comprising a heating device for cyclically heating at least one of the cylinder head and motor member to a preheating temperature and a curing temperature and further comprising a preheating zone to preheat the cylinder head in advance of the pressing device.
21. 21. The pressing device according to claim 20, characterized in that the preheating temperature is about 60 ° C and the curing temperature is about 150 ° C.