DE3039868A1 - VIBRATION DAMPER AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Description

Patronage Dipl.-Ing. Cu rt WaI Iach

Dipl.-Ing. Günther Koch

ν Dipl.-Phys. Dr Tino Haibach

Dipl.-Ing. Rainer Feldkamp

D-8000 Munich 2 Kaufingerstraße 8 Telephone (0 89) 24 02 75 Telex 5 29 513 wakai d

Date: October 22nd, 1989

Our reference: 17 0 ^ 4 - Κ / Αρ

Applicant: Barry Wright Corporation

680 Pleasant Street
Watertown, Massachusetts
United States

Title: Vibration Damper and Procedure

for its manufacture

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The invention relates to improvements in vibration dampers and in particular to a novel form of such a vibration damper and a novel method for the production.

Vibration dampers come in numerous embodiments known. The invention relates primarily to plate-like or tubular vibration dampers that are referred to because they are either short in length in relation to their diameter and so relatively are flat, while the other group has a relatively large axial length compared to the diameter. Acquaintance Vibration dampers generally consist of inner and outer metal parts and one injection molded produced elastomeric part, which runs between the metal parts and is glued to them. These Construction allows the manufacture of vibration dampers in different sizes for different Load ranges, the manufacture comprising several stages which increase the cost of the end product and which must be done carefully in order to obtain a reliable product. Among these different stages of manufacture is the important stage of cleaning the metal components and applying an adhesive on the metal parts so that a connection is made with the elastomeric part, and then the components placed in the mold to inject the elastomeric part. The injection molded product must be heated to ensure complete vulcanization of the elastomer. In addition, a shear strength is between

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27.6 and 34- »5 bar (400 to 500 psi) desired-to one To prevent separation of the elastomeric intermediate piece from the metal parts and to ensure that the Vibration dampers have met commercial requirements for a long time. This high shear strength can only through careful selection and compliance with manufacturing requirements are obtained, in particular the ITorm temperatures and pressures must be precisely controlled.

The invention is therefore based on the object of a novel and improved method for producing plate-like or tubular vibration shock absorber and a new and improved form for producing such To create a damper.

The invention also aims to produce vibration dampers of the type described, with im essentially the problems and limitations of previous manufacturing processes be avoided.

Another object of the invention is to create a manufacturing method for vibration and shock absorbers, which makes it faster and cheaper to work than in known methods used in the prior art.

This object is achieved according to the invention in that two different synthetic plastic materials can be used for a simultaneous spraying process. One plastic material is a rigid thermoplastic Material and the other a thermoplastic elastomer. The latter is injected into the mold,

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after the rigid thermoplastic material has already been injected is. This sequence of injection is observed to ensure proper fusion of the to ensure both materials at their points of contact.

Exemplary embodiments of the invention are described below with reference to the drawing. In the drawing show:

Pig. 1 shows an axial section of a plate-like vibration damper according to a preferred embodiment the invention,

2A to 2C are sectional views showing different positions of an injection mold assembly; which is used to manufacture the vibration damper according to Fig. 1,

Fig. 3 and 4 of Fig. 1 corresponding axial sections two further embodiments of vibration dampers according to the invention.

The plate-like vibration damper shown in Fig. 1 consists of an inner part 2 and an outer part 4- as well as a Zxd-piece 6. inner and outer part are made of relatively rigid thermoplastic material, while the intermediate piece is made of a thermoplastic Consists of elastomer. The term "substantially rigid thermoplastic material" means that it is is a massive, substantially rigid material which is melted (i.e., it always will

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softer until it becomes liquid x) when it is heated to a suitable temperature, and it is hardened and becomes solid and essentially rigid when it is cooled ^{to room temperature, for example 21 ° C.} The term "thermoplastic elastomer" denotes a solid material which has the property that it melts when heated to a suitable temperature and that it hardens and becomes solid and elastic and behaves as an elastomer when cooled to room temperature will. These thermoplastic materials can consist of a single thermoplastic polymer substance or a mixture of such substances, it being possible to add additives such as colorants, plasticizers, antioxidants, stabilizers and other ingredients which modify one or more physical properties of the thermoplastic substance.

Another requirement of the invention is that parts 2, M and 6 are injection molded. Accordingly, the substantially rigid thermoplastic material and the thermoplastic elastomeric material must consist of injection molding materials which can be processed by injection molding. The materials can mainly consist of one or more polymerization products and / or one or more copolymers. In addition, the material which is used to produce the parts 2 and M and the material which is used to produce the intermediate piece 6 should be compatible in the sense that the materials can be connected to one another by fusion, ie by contact of materials while

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at least one of the materials is in a liquid state, after which the liquid material is then cooled until solidification and a connection with the other material is complete. The parts 2 and 4 can consist of different compatible materials which melt and solidify at approximately the same temperatures, but it is expedient to manufacture the two parts from the same material. Parts 2 and 4 preferably have a flexural modulus of over 27-600 bar (400,000 psi), while the intermediate piece 6 consists of a soft thermoplastic elastomer with a low modulus, which has a hardness value between 35 and 85 according to a hardness meter with a Shore Α scale having. For example, parts 2 and 4 are made of polystyrene with a flexural modulus of about 32,085 bar (465-000 psi) and the intermediate piece consists of butadiene styrene compounds with a hardness value of 55 ₅ measured with a hardness meter with a Shore A scale a.

The parts 2, 4 and 6 are shown in the drawing as if they have sharp boundaries, however are, as mentioned in detail below, provided transition areas between those parts that are free of Mixing or diffusion phenomena of the thermoplastic material are.

As can be seen from Fig. 1, the inner part 2 has a flat annular upper surface 8 and a lower one annular surface 10, an inner cylindrical surface 12 defining an axial bore 17, and an outer boundary that acts as the rotating body surface

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is formed, and has cylindrical end sections 16 and 16 and a double-curved intermediate section 20. The outer part 4 serves as a flange for the vibration damper assembly and has a cylindrical outer surface 22 and an inner boundary 24, which is formed as a cylindrical surface, as well as an upper singing surface 26 and a surface 28 running parallel thereto, and these surfaces are parallel to the corresponding surfaces of the inner ring 2 and extend perpendicular to the axis of the inner part. The outer part 4 has several bearing holes 5. The intermediate piece 6 has an inner section 30 and an outer section 32 which are respectively attached to the inner part 2 on the transition section 18 and to the part 4 on the inner transition part 24, and the intermediate piece also has a curved one Transition section 34 which runs between the inner part 2 and the outer part 4. The transition section 34 is fixed to the inner part 2 in the transition section 20. The transition section 34 acts as a spring in order to elastically support the inner part 2 with respect to the outer part 4.

When the device shown in Fig. 1 is manufactured by the molding process described below, then there is essentially no diffusion or mixing of one material with the other at the interfaces instead of. In addition, there is little distortion of one material by the other along the length of the Border areas. By checking the cross-sections of the shock absorber of Fig. 1 made according to the invention it has been found that when viewed with a scanning electrode microscope with a magnification

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scale 1:20 000 the boundary areas between the butadiene styrene thermoplastic elastomer and the polystyrene parts have an intermediate area (the diffusion area or the mixing of one material with the other) which is on the order of only 25 * 4 x 10 "mm in thickness. Nonetheless, the joint is between the elastomeric and non-elastomeric parts is sufficiently strong to be satisfactory to act as a vibration damper.

Reference is now made to FIGS. 2A to 2C. The device according to FIG. 1 was according to the invention with a preferred manufacturing method by means of a Injection mold made of three relatively movable mold parts 36, 38 and 40 and a core 42 exists, which is fixed on the molded part 36. As shown in Fig. 2A, the molded body 36 has a profiled one inner end face with four discrete step sections 44, 46, 48 and 50, while the molded body 38 has a has a flat inner end face 52 and a cylindrical inner surface 54. The molded body 40 has a profiled inner face with sections 56 and 58 and a cylindrical outer surface 60 that is in a tight, sliding fit with surface 54. The moldings are arranged so that when the molded bodies are in the closed position, the surfaces 50 and 52 one on top of the other fit, while surfaces 44 and 58 and pin 42 form a first cavity 62, while the Surfaces 48 and 52 and the upper portion of surface 60 form a second cavity 64. The molded body 40 has a central hole 66 in which the center pin 42 fits with a tight interference fit. Multiple pins 68

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of the inner molded body 36 are in a sliding fit in holes 70 of the molded body 38. The pins 68 serve as cores for producing the bearing holes 5 · The molded bodies 36, 38 and 40 are so arranged (by conventional means not shown in the drawing, but which are clear to those skilled in the art) that they can move relative to one another along the axis of the pin 42 ", so that the moldings 38 and 40 are separately bexireglich and can be fixed in different positions along the axis relative to the molded body 36.

The vibration damper of Fig. 1 is made according to the following using a mold structure shown in Figs. 2A to 2C Process manufactured. First, the molded parts 36, 38 and 40 are transferred into the closed position according to FIG. 2A (this is the first injection position) and it becomes a suitable liquid thermoplastic injection molding material injected, which is capable of being solidified into a rigid solid body (for example Polystyrene), and this material is injected into the mold cavities 62 and 64- through the injection ports 74 and 76, so that parts 2 and 4 are manufactured in this way. Then the molded body 40 is withdrawn, until the outer edge of its surface 56 with the surface 52 is aligned, whereby a third cavity 78 is formed as can be seen from FIG. 2B (this forms the second injection position). After that, a suitable one injected liquid thermoplastic injection molding material, which forms a solid body with properties an elastomer is solidified, for example butadiene styrene, and this material becomes in the cavity 78 via one or more injection openings 80

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injected so that the transition piece 6 is formed. This injection step is performed after the material injected into cavities 62 and 64 has solidified or at least become so viscous that it is no longer displaced or distorted when the material is injected through orifice 80. However, it must be soft enough to bond with the elastomeric material. Accordingly, the second injection stage is carried out while the material in the cavities 62 and 64 is still hot, but after it has already solidified. By suitable choice of materials it is possible for the cavity 78 to be filled in as little as 3 seconds after the cavities 62 and 64 are filled, and a satisfactory connection between the elastomeric and non-elastomeric parts can still be ensured . After the intermediate piece has set in the cavity 78 6 and forms a solid body, after the mold parts are separated from the mold part 36 38 and 40, \ i ± e can be seen in Fig. 2C, whereupon the final damper removed from the mold and can be set aside to cool. The molded parts are then returned to the position shown in FIG. 2A so that the next molding process can be initiated.

According to the preferred method of the invention the parts 2 and 4 of the vibration damper formed from polystyrene, which solidifies in such a way that a flexural modulus of about 32,085 bar (465 x 000 psi) is obtained, and the vibration damper adapter 6 consists of one Butadiene-styrene mixed polymerizate which solidifies in such a way that it has a hardness on the Shore A scale

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between 35 u ^ -d 85 (depending on the required spring rate), the polystyrene is preferably the material which is marketed by Shell under the trade name Shell DP-203, and the butadiene styrene is a material, which is sold by the Shell company under the name Kraton 3OOO Series thermoplastic rubber. Appropriate temperatures and pressures are determined by the properties of the material used, ie the mentioned polystyrene material is under a pressure of about 345 bar (500 psi) at a temperature of about 200 ^° C (390 ^° F) and the butadiene styrene material is injected into cavity 78 at a pressure of about 414 bar (6000 psi) and a temperature of about 200 ^° C (390 ^° F). The last-mentioned injection should expediently take place 1 to 3 s after the injection of the polystyrene molded material into the cavities 62 and 64 has ended. The injection molding materials are kept at a temperature of approximately 200 ^° C. (390 ^° F.) during the two injection processes, but the mold should be kept at a temperature between approximately 38 ° C. and 66 ° C. during the molding process. The mold is then opened and the finished part is opened approximately 1 minute after the second injection is completed. The part so formed is then set aside and allowed to cool to room temperature before it is labeled, tested and packaged. The finished products exhibit a shear bond strength between parts 6 and 2 or 6 and 4 of at least 27.6 to 34.5 sjc and usually between 41.4 and 55 2 bar. As a comparison, there is a connection strength of about 34.5 bar between metal in conventional vibration metal connections

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and elastomer.

In this connection it should be noted that the injection of the elastomeric material after the injection has taken place of the rigid material is critical. It has been shown that when the elastomer is simultaneously or before the rigid material is injected, a satisfactory final product cannot be obtained because the elastomer is unable to withstand the deformation in cavity 78 under the required and applied Resist pressure as the plastic material is injected into the cavities 62 and 64. This is true even when the elastomeric material is fully cured before the non-elastomeric material is injected. Only if the injection of the elastomeric material is delayed until the rigid plastic material is sufficiently set has, in order to withstand deformation under a given pressure, which is required, the elastomeric material Injecting it becomes possible to establish a connection between the elastomeric material and the non-elastomeric material To create material that is strong enough, and it also creates a vibration damper that does just that Shape of the three mold cavities corresponds.

Another important advantage of the invention is that the spring rests of the vibration damper are changed as a result the composition can be changed, and this changes the hardness of the material, which is used for the intermediate piece 6. For example, there is a Kraton molding material from the Shell company available, which under the name Kraton 3226 has a hardness of 35 according to the Α scale,

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while a material Kraton 3202 has a hardness of 55 der Α scale. A material Kraton 3204- has a hardness of 85 on the Α scale. Other hardness values can thereby can be achieved by appropriately mixing the three materials or other thermoplastic elastomers adds. The stiffness of parts 2 and 4 can be changed by adding some elastomeric molding material mixed with the polystyrene molding material. The parts 2 and A- do not need to be absolutely rigid and in certain applications of the vibration damper it can suffice or even be desirable, these parts only stiff, d. H. semi-hard to shape.

Another advantage of the method according to the invention is that the molding materials are injected coaxially instead of using a biaxial process as described in TJS-PS 3,950,483 is. It has been found that molding by coaxial injection is easier to carry out and more reliable in operation Product leads.

Another advantage of the invention is that vibration dampers of various shapes, sizes and Vibration damping characteristics can be produced. For example, the shape and / or size of the intermediate piece 6 can only be changed by modifying the various molded parts. Also is created the possibility of using a flat insulator 90 (Fig. 3) by appropriate design of the mold structure to create, which consists of a cylindrical inner part 2A, a cylindrical outer part 4A with a flat king flange 92 and a cylindrical intermediate piece 6A

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that has flat end faces ". In addition, it is possible, an axially elongated vibration damper 96 (Fig. 4) to create "in which the three parts 2B, 4-B and 6B are all cylindrical and the length of part 6B considerably exceeds the inner radius and the outer radius. The two alternative forms of vibration dampers have vibration isolation characteristics, which are different from those of the embodiment of Fig. 1 even if the same materials as this Embodiment were used.

Another advantage of the invention is that it can be used in conjunction with a wide variety of thermoplastic Injection molding materials can be realized. The thermoplastic elastomer material that the Intermediate piece 6 forms, also consist of materials other than butadiene styrene. The term "thermoplastic Elastomer "is a term which is clear to the skilled person and which is used, for example, in the book of Tobolsky et al "Polymer Science and Materials", p. 27? (Wiley-Interscience) (1971) »is described. Like in that "Handbook of Thermoplastic Elastomers" (1979) by A. A. Walker, there are a variety of such materials.

Also, for example, the rigid thermoplastic Parts 2 and 4 made of acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (Plexiglas) or a polypropylene polymerisation product or other products, as for example in US Patents 3 94-1 859, 3,962,154 and 4,006,116. The exact choice the materials used depends on the one you want

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Cliarcharacteristics and the compatibility of the elastomeric material with the non-elastomeric materials in view of a mutual connection.

Claims (18)

Patent Attorneys Cipi.-Ing. Curt Wallach Dipl.-Ing. Günther Koch Dipl.-Phys. Dr Tino Haibach Dipl.-Ing. Rainer Feldkamp D-8000 Munich 2 Kaufingerstraße 8 Telephone (0 89) 24 02 75 Telex 5 29 513 wakai d Date: 22 _O October I98O Our reference: Λ ⁷ ] 0 ^ 4 K / lTu Claims (1.! Vibration damper, characterized that it consists of two concentric to one another in the Spaced first and second parts (2 and 4) made of rigid thermoplastic polymerisation material and a third part (6) which extends between the first and second parts and is fixed to these, and that the third part is made of a thermoplastic organic Elsstornermaterial and on the first and second part by direct molding of the thermoplastic organic polymerisation material is attached. 2. Vibration damper according to claim 1, characterized in that the third part is on the first and second parts by direct fusing of the thermoplastic elastomeric material is attached to the thermoplastic polymerization product. 3 · Vibration damper according to claim 1, characterized 130018/0004 ORIGINAL INSPECTED _ ₂ _ 3039869 characterized in that on the connecting surfaces at which the third part (intermediate piece) is in contact with the first and second parts
are. stands, fused to a depth of 25.4-2c 10 "mm 4. Vibration damper according to claim 1, characterized ge - ken η ζ eichnet that an outer flange is formed by the first part and that the second Part has an inner sleeve portion. 5. Vibration damper according to claim 4-, characterized in that the intermediate piece (6) is formed corrugated in radial cross section. 6. Vibration damper according to claim 4-, characterized g e mark calibrates that it has a central axis and that the second part measured parallel to the axis, is considerably larger than the corresponding one Dimension of the first part. 7. Vibration damper according to claim 6, characterized in that the third part has a outer ^ section attached to the first part, an inner section attached to the second part, and a bridging section between the inner and the outer portion and that the outer portion is fused to the first constriction and is surrounded by this and that the inner part at least on part of the outer section 13 & ÖU / O9 & * is fixed and surrounds this part. 8. Vibration damper according to claim 7 »characterized in that the intermediate piece in runs at an acute angle to the axis. 9. Vibration damper according to claim 1, characterized in that the first and second Parts are made from polystyrene, which has a flexural modulus greater than 27,600 bar (400,000 psi). 10. Vibration damper according to claim 1, characterized in that the third part consists of a soft material with a low modulus and a hardness between 35 u ^ d 85 according to the Shore A scale owns. 11. Vibration damper according to claim 10, characterized in that the third part is eichnet consists of a copolymer of styrene and butadiene. 12. Vibration damper according to claim 1, characterized in that the first part and the second part are tubular. 13. Vibration damper according to claim 12, characterized in that the first part has a having tubular portion surrounding the third part and attached to it, and that a 130011/0904 303986a Flange, integrally formed rait the pipe section is. 14-. Vibration damper according to claim 12, characterized in that the second part is longer is than the first part and that a portion of the second part has the same extension as the second Part over the length of the second part. 15 · "Method of manufacturing a vibration damper according to one of claims 1 to 14 with a first and a second concentrically spaced from one another lying part made of rigid thermoplastic non-elastomeric material, and a third part made of thermoplastic elastomer Material which runs between and is connected to these two parts, characterized in that (a) the first and second parts by injection molding simultaneously in a first and second mold cavity are generated and (b) the third part between the first and second parts is manufactured by injection molding such that the thermoplastic elastomer material from which the third part is made, directly with the thermoplastic non-elastomeric material is fused to make up the first and second parts are made. 130018/0904 3039368 16. The method according to claim 15, characterized in that the third part is injected after the thermoplastic polymer material has set, but before it reaches its maximum hardness has reached. 17 · The method according to claim 15, characterized in that the first and the second part consist of polystyrene. 18. The method according to claim 15, characterized in that the third part consists of one There is a mixed polymer of styrene and butadiene. 130018/0904