JPS62167951A - Vibration isolator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to vibration isolators and, more particularly, to a new type of vibration isolator. Many different types of vibration isolators are known and the subject of this invention is Mainly plate-shaped and tube-shaped vibration insulators. Plate-shaped vibration insulators are those with a small length-to-diameter ratio and are therefore generally flat, and tubular vibration insulators are those with a large length-to-diameter ratio. Conventional insulators of this type include inner and outer metal portions and an elastomeric molded portion extending between and affixed to the metal portions. Although this well-known configuration allows insulators to be produced in a wide range of sizes and load ranges, its manufacture involves many steps that increase the cost of the product and do not improve product reliability. must be carried out carefully. The most important of these steps is to clean the metal part, apply an adhesion modifier or adhesive to it to facilitate bonding of the metal part to the elastomer part, and then place the components in a mold to form the elastomer. Sixth, the part must be heated to fully cure the elastomer. Sixth, the elastomer part must be prevented from separating from the metal part, and the insulation must meet commercial requirements. Approximately 400 to 5
A shear bond strength of 0.00 psi (approximately 28-35 KVIL2) is desired.

This level of joint shear strength can only be achieved through proper design and strict compliance with manufacturing requirements, including proper control of molding temperature and pressure.

A primary object of this invention is to provide new and improved plate and tube vibration or shock insulators.

This objective is achieved by manufacturing the insulation from two different synthetic materials using a co-molding method. One synthetic material is a rigid thermoplastic material and the other material is a thermoplastic elastomer. The latter is injected after the rigid thermoplastic material. This injection molding sequence is used according to the invention to obtain a suitable bond of the two materials.

Next, preferred embodiments of the invention shown in the drawings will be described in more detail.

FIG. 1 shows a plate-shaped vibration insulator consisting of an inner part 2, an outer part 4 and an intermediate part 6. The inner part 2 and the outer part 4 are made of substantially rigid thermoplastic material, and the intermediate part 2 and 4 are made of a substantially rigid thermoplastic material. Part 6 is made of thermoplastic elastomer. As used herein, a "substantially rigid thermoplastic material" refers to a material that melts (softens to a liquid state) when heated to an appropriate temperature.
The term "thermoplastic elastomer" means a solid, substantially rigid material having the property of becoming substantially rigid when cooled to room temperature, i.e., 70F (2L1C); the term "thermoplastic elastomer" A solid material that has the property of melting when heated and becoming a solid that exhibits elastic, elastomeric behavior when cooled to room temperature.

These thermoplastic materials may be a single thermoplastic polymeric material or a mixture of multiple such materials, and may include coloring agents, plasticizing agents, oxidation resistant agents, stabilizing agents, or one or more other physical properties of the thermoplastic material. It may or may not contain other functional ingredients that suitably modify the

Another requirement of the invention is that the parts 2, 4.6 are manufactured by injection molding. Substantially rigid thermoplastic materials and thermoplastic elastomers must therefore be made of injection moldable molding materials, which consist of one or more polymers or one or more copolymers, or consist primarily of one or more polymers or copolymers. It is good to be something that consists of Furthermore, part 2
, 4 and the material used to manufacture part 6 are melted, i.e., at least one of them is in a fluid state (at which time the two materials are brought into contact, and then the material in the fluid state is solidified). The parts 2, 4 must be cooperating in the sense that they are joined together by cooling until they form a bond with the other material. Parts 2, 4 must be cooperating, melting and solidifying at the same or nearly the same temperature. Although they may be made of different materials exhibiting properties, it is preferable that they be made of the same material. Portions 2 and 4 have a deflection modulus of 400.0.
00 psi (approximately 28,000 to 9/aIL2) or higher, but portion 6 is a flexible material with a low deflection modulus having a Shore A scale durometer value of 35 to 85. - As an example, section 2.4 has a deflection modulus of approximately 465,000 psi (approximately 52550'7-z)
Part 6 is a butadiene styrene compound with a Shore A durometer of 55.

The parts 2, 4.6 are shown to have well-defined boundaries, with the interface between the parts being substantially independent of intermixing or interdiffusion of thermoplastic materials, as will be explained below.

Further, with reference to FIG.
2, and has an outer boundary represented as a surface of revolution comprising a cylindrical tip section 16.degree. 18 and an intermediate section 20 with convex and concave surfaces.

The outer part 4 is used as a flange of the insulator unit and has a cylindrical outer surface 22, an inner border 24 expressed as a cylindrical surface and a top surface 26 and a bottom surface 28 parallel to each other;
The top surface 26 and the bottom surface 28 are parallel to the corresponding top surface 8 and bottom surface 10 of the inner part 2 and extend perpendicularly to the axis of the inner part 2. The outer part 4 also has a plurality of mounting holes. The intermediate part 6 has an inner section 30 and an outer section 32, which sections 30.52 are joined to the tip section 18 of the inner part 2 and to the inner border 24 of the outer part 4, respectively.

The intermediate section 6 has a convoluted intermediate section 34 extending between the inner section 2 and the outer section 4 . Intermediate section 3
4 is joined to the inner part 2 at the intermediate section 20. The intermediate section 34 acts as a spring elastically positioning the inner part 2 with respect to the outer part 4.

When the device of FIG. 1 is manufactured by the molding method described below, there is little diffusion or mixing of one material into the other. Furthermore, little or no distortion of one material by the other material along the boundary zone occurs. Magnification 20,00
By examining an insulator according to the present invention as shown in FIG. 1 with a scanning electron microscope at 0.000 m, it was determined that the boundary between the butadiene styrene thermoplastic elastomer portion and the polystyrene portion was only 1.0 x 10". inches (approx. 2.5
It has been shown that the interfacial zone (intermixing zone of one material with the other or zone of diffusion from one material to the other) of the order of 4 x 10" m) is thick. Nevertheless, the bond between the elastomeric and non-elastomeric portions is sufficiently strong for the device to function satisfactorily as an insulator.

According to a preferred embodiment of the invention, the insulator shown in FIG. 1 is secured to three relatively movable mold members 36, 38, 40 and mold member 36, as shown in FIGS. 2A-20. It is manufactured by a joint injection mold mainly consisting of a central member, that is, a core 42. As shown in FIG. 2A, mold member 36 has a contoured inner end surface including four individual portions 44, 46, 48, 50, and mold member 38 has a flat inner end surface 52 and a cylindrical inner surface. It has 54. Mold member 4
0 is the contoured inner end surface and inner surface 5 including section 56.58
4 and a cylindrical outer surface 60 that is a tight sliding fit.

The mold member 56.38° 40 and the core 42 have portions 50 and end faces 52 aligned with each other when the member is in the closed position;
Portion 44, section 58, and core 42 form a first mold cavity 62, and portion 48, end surface 52, and an upper portion of outer surface 60 form a second mold cavity 64. The mold member 4o has a center hole 66 into which the core 42 is inserted.
are tightly fitted together. A plurality of pins 36 fixed in the mold member 36 are snugly fitted into the holes 7o in the mold member 38. The pin 68 is used as a core for forming the hole 5 during attachment. The mold parts 36, 38, 40 are movable relative to the axis of the core 42 by means not shown, which are customary in injection molding technology, so that the mold parts 58, 40 are moved along said axis with respect to the mold part 36. may be individually and selectively moved to different positions along the line.

The vibration insulator shown in FIG. 1 is manufactured as follows using the mold assembly shown in FIGS. 2A-20. First, mold member 56.
58.40 in the fully closed position (first injection position) shown in FIG. Injected into the mold cavity 62, 64 through
Form parts 2 and 4. The mold member 40 is then retracted until the outer edge of the section 56 is flush with the end surface 52, forming a sixth mold cavity 78 as shown in FIG. 2B.
injection position). A suitable liquid thermoplastic injection molding material (e.g., butadiene styrene) capable of solidifying into a solid material having elastomeric properties is then injected into the mold cavity 78 through one or more injection ports 80; Form part 6. This injection process
The material injected therein has solidified or become viscous enough to not be displaced or spread by the material injected through injection port 80, but is flexible enough to adhere to the elastomeric material. This will be done later. That is, the second injection step is performed after the material in the cavities 62, 64 has hardened as a solid while still hot. Proper selection of materials will allow filling of cavity 78 within a short period of 1 to 3 seconds after cavities 62, 64 are filled and still provide a satisfactory bond between the elastomeric and non-elastomeric portions. It will be done. Finally, after portion 6 has hardened as a solid in cavity 78, mold members 38, 40 are pulled away from mold member 66, as shown in Figure 2c, and the finished insulator is removed from the mold assembly and released. Cool down. Thereafter, mold members 56, 38, 40 and core 42 are returned to the position shown in FIG. 2A for the next molding cycle.

In the above-described preferred embodiment of the invention, the portions 2, 4 of the insulator have a deflection modulus of about 46soop
ff1 (approximately 52,550 sous), section 6 has a durometer value of 35 to 85 (depending on the desired modulus of the insulator) as measured on the Shore A scale. It is made from a butadiene restyrene copolymer that is solidified into. A preferred polystyrene is manufactured by Shell under the trade name Shell DP-20.
Butadiene styrene is a material sold under the trade name Kraton 3000 Series Thermoplastic Rubber by Shell Company. Appropriate temperatures and pressures are determined by the properties of the materials used. That is, the polystyrene molding materials mentioned above are generally sooty.

psi (approximately 350 psi) and approximately 390 psi (approximately 198 psi) pressure
The butadiene styrene molding compound described above is injected at a temperature of about 6000 psi (about 42 a K9/,
L2) (D) is injected into the cavity 78 at a pressure of about 390°C (19s, 9°C). This should be done after 1-3 seconds.The injection material should be kept at about 390"F during both injection steps.
The mold is maintained at a temperature of about 100° to 50"F (57,8° to 65rC) during both injection steps. After the completion of the second injection step 1 After about 1 minute, the mold is opened and the completed molded product is taken out.The molded product is then allowed to cool to room temperature, and then labeled, tested and packaged.0 Part 6 of the completed molded product The shear bond strength between and parts 2, 4 is at least 400 to 5 oopsi (
about 28-35 ζ2), usually about 600-5 oopei
(approximately 42 to 56 vertical), compared to a typical bond strength between a metal portion and an elastomer portion of conventional metal-elastomer insulators of approximately 500 psi (approximately 3
5 and Mouse 2).

It is important here that the elastomeric material is injected after the rigid material has been injected. If the elastomer material is injected simultaneously with or before the injection of the rigid material, the elastomer in the cavity 78 will not change under the pressure required to inject the rigid material into the cavity 62,64. A satisfactory insulator cannot be obtained because it cannot withstand it. The same is true if the elastomer is fully cured before injection of the non-elastomeric material. A sufficiently strong bond between the elastomeric and non-elastomeric portions can only be achieved if the injection of the elastomeric material is delayed until the rigid material has sufficiently cured to withstand deformation under the pressures required for injection of the elastomeric material. It is possible to precisely adapt each part of the insulation to the shape of the three mold cavities 62, 64, 78.

Another advantage of the invention is that the modulus of elasticity of the insulator can be varied by varying the composition, and thus the durometer, of the material used to form the intermediate section. - As an example, 35
For the durometer A scale, see [Craton 52
Shell molding materials such as 26J, 55 durometer A scale are known as Kraton 5202J, and 85 durometer A scale are known as Kraton 5
Molding materials such as 204J are commercially available. Other suitable durometer values can be achieved by appropriately blending any two or all three of these molding materials, or by adding or substituting other thermoplastic elastomers.

The stiffness of the parts 2, 4 can be modified by mixing some elastomeric molding material with the polystyrene molding material. In this connection, parts 2, 4 need not be absolutely rigid; depending on the application of the insulator, it may be sufficient or even desirable for parts 2, 4 to be merely semi-rigid. be.

Another advantage of the present invention is that the two
Injection molding of a molding material is performed by a coaxial method instead of an axial method. Coaxial injection molding has been found to be simpler and to produce more reliable molded parts.

Yet another advantage of the present invention is that insulators can be molded with a variety of shapes, sizes, and vibration isolation properties.

- By way of example, the shape and/or size of the intermediate part 6 can be changed by changing the respective mold part. In addition, by appropriately molding the mold assembly, a flat insulator 90 (second part) consisting of a cylindrical inner part 2A, a cylindrical outer part 4A with a flat circular flange 92, and a cylindrical middle part 6A with a flat end surface. (see Figure 3).

Another example is an axially elongated insulator 96 (see FIG. 4) in which all six sections 2B, 4B, 6B are cylindrical and the length of section 6B substantially exceeds its inner and outer diameters. Made.

Can be built. Although these two insulators are made from the same material as the insulator of FIG. 1, they have different vibration isolation properties.

Yet another advantage of the invention is that a variety of thermoplastic injection molding materials can be used. That is, the thermoplastic elastomer molding material forming portion 6 may be any material known in the art other than butadiene styrene. The term "thermoplastic elastomer" is a term well known to those skilled in the art, as demonstrated by Tobolsky et al., "Polymer Science and Materials," p. 277, published by Wiley Interscience (N+71). A large number of materials of this type exist, as disclosed in Thermoplastic Elastomers Handbook J (1979) by John Walker.

The rigid portions 2, 4 may also be described in US Patent No. 594, for example.
No. 1859, No. 3962154 and No. 400611
As taught in No. 6, acrylonitrile-butadiene styrene (ABS), polymethyl methacrylate (plexiglas x polypropylene polymer) and other materials known in the art may be used.

The selection of materials used depends on the cooperativity and desired properties of the elastomeric and non-elastomeric materials for mutual adhesion.

Many other variations of this invention, which will be obvious to those skilled in the art, are possible and are all intended to be encompassed within the scope of this invention.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a plate-shaped vibration insulator according to a preferred embodiment of the present invention, and FIGS. 2A to 2C show different injection mold assemblies used for manufacturing the vibration insulator of FIG. 1. 3 and 4 are side sectional views of vibration isolators according to two alternative embodiments of the invention. In the figure, 2: inner part (first part), 4: outer part (second part), 6: intermediate part (third part), 8: top surface, 10: bottom surface. FIG, 1 0G, 3FIG, 4

Claims (1)

Claims: 1. Concentric, substantially spaced-apart first and second portions of rigid thermoplastic polymeric material and extending between the first and second portions; a third portion affixed to the first portion and the second portion, the third portion being made of a thermoplastic organic elastomer material and affixed to the first portion and the second portion by direct bonding of the thermoplastic organic polymer material; body. 2. The third portion is attached to the first portion as a result of direct fusion of the thermoplastic elastomer material and the thermoplastic polymer material.
The vibration insulator according to claim 1, wherein the vibration insulator is adhesively bonded to the first part and the second part. 3. The vibration isolator of claim 1, wherein said third portion is bonded to said first and second portions at a depth of approximately 2.54 x 10^-^6 cm. 4. The vibration insulator of claim 1, further comprising an outer flange formed by the first portion and an inner sleeve portion formed by the second portion. 5. The vibration insulator according to claim 4, wherein the third portion has a convoluted radial cross section. 6. The vibration isolator of claim 4, having a central axis, and wherein the dimensions of said second portion, measured parallel to said central axis, are substantially larger than the corresponding dimensions of said first portion. 7. The third part has an outer part fixed to the first part, an inner part fixed to the second part, and an intermediate part connecting the outer part and the inner part, and the outer part A vibration insulator according to claim 6, wherein the vibration insulator is joined to and surrounded by the first portion, and the inner portion is joined to and surrounded by at least a portion of the second portion. . 8. The vibration insulator according to claim 7, wherein the intermediate portion extends at an acute angle with respect to the central axis. 9. The first part and the second part are approximately 28,000 kg/
The vibration insulator according to claim 1, which is made of polystyrene having a deflection modulus of cm^2 or more. 10. The vibration insulator according to claim 1, wherein the third portion is made of a flexible material with a low deflection modulus having a hardness value of 35 to 85 on a Shore A durometer. 11. The vibration insulator according to claim 10, wherein the third portion is made of styrene-butadiene copolymer. 12. The vibration insulator according to claim 1, wherein the first portion and the second portion are tubular members. 13. The vibration isolator of claim 12, wherein said first portion includes a tubular section surrounding and joined to said third section and a flange section integrally formed with said tubular section. 14. The second portion is longer than the first portion, and a portion of the second portion is coextensive with the second portion along the length of the second portion. Vibration insulator.