Damping pad for wire race bearing and method for manufacturing the same

Abstract

The present disclosure provides a damping pad for a wire race bearing, the wire race bearing comprising a housing and a wire, and the damping pad being arranged between the housing and the wire to partially enclose the wire; wherein the damping pad comprises a reinforcing fiber thread embedded inside the damping pad in the circumferential direction and bonded with the damping pad, the reinforcing fiber thread having a lower elongation rate and a higher tensile strength relative to the damping pad. The present disclosure also provides a method for manufacturing the damping pad as described above, comprising: step 1: performing pre-treatment to the reinforcing fiber thread; step 2: introducing the reinforcing fiber thread into an extrusion head for extruding the damping pad to reach an extrusion position corresponding to an embedding position of the reinforcing fiber thread in the damping pad; step 3: co-extruding the damping pad with the reinforcing fiber thread through the extrusion head. According to the present disclosure, when the reinforcing fiber threads are coupled to the damping pad, various deformations caused by the above factors are hindered under the extrusion curing process and the storage conditions, so that the damping pad is dimensionally stable.

Description

DAMPING PAD FOR WIRE RACE BEARING AND METHOD FOR MANUFACTURINGTHE SAMETECHNICAL FIELD

[0001] The present disclosure provides a damping pad for a wire race bearing and a method for manufacturing the same.BACKGROUND

[0002] Wire race bearings are a uniquely structured bearing and can be applied to a various scenarios. A wire race bearing generally comprises rolling elements, wires in contact with the rolling elements and having raceway surfaces, a housing receiving the rolling elements and the wires, and the like. The wires are generally arranged at diagonal positions of the rolling elements and may for example comprise one pair of wires arranged along one set of diagonal positions or two pairs of wires arranged along two sets of diagonal positions. Typically, the wires are placed at respective recesses of the housing, which recesses are constituted by walls perpendicular to each other. Generally, in a wire race bearing, a damping pad provided between the recess and the wire is made of elastomer.

[0003] Wire race bearings, and in particular wire race ball bearings, are widely used in medical imaging devices such as CT machines. However, vibration of the wire race bearing is a pain point for CT machine applications. An elastomeric damping pad is commonly used in the prior art to reduce vibration, but aging of the elastomer is in close relevant to bearing performance. In particular, when the damping pad is pressed for a long time, it is likely to lose elasticity and fail to recover, and secondly, the damping pad is usually submerged in grease for lubricating the rolling elements, the wires and the like, and the volume and hardness of the damping pad will be changed. Changes in the physical and chemical property of the damping pad may result in changes in bearing play. Further, the damping pad may experience volume shrinkage during storage, rendering the damping pad dimensionally unstable.

[0004] Accordingly, there is a need in the art for a damping pad that overcomes the above problems.SUMMARY

[0005] In view of the above-mentioned problems and needs, the present disclosure proposes a novel technical solution, which solves the above-mentioned problems due to adopting the following technical features, and brings about other technical effects.

[0006] The present disclosure provides a damping pad for a wire race bearing, the wire race bearing comprising a housing (1) and a wire, and the damping pad being arranged between the housing (1) and the wire to partially enclose the wire; wherein the damping pad comprises a reinforcing fiber thread embedded inside the damping pad in the circumferential direction and bonded with the damping pad, the reinforcing fiber thread having a lower elongation rate and a higher tensile strength relative to the damping pad.

[0007] The present disclosure also provides a method for manufacturing the damping pad as described above, comprising: step 1 : performing pre-treatment to the reinforcing fiber thread; step 2: introducing the reinforcing fiber thread into an extrusion head for extruding the damping pad to reach an extrusion position corresponding to an embedding position of the reinforcing fiber thread in the damping pad; step 3: co-extruding the damping pad with the reinforcing fiber thread through the extrusion head.

[0008] According to the present disclosure, when the reinforcing fiber threads are coupled to the damping pad, various deformations caused by the above factors are hindered under the extrusion curing process and the storage conditions, so that the damping pad is dimensionally stable. Thus, in the final assembly process of the product, the difficulty of assembly can be reduced based on the correct cut length and the higher dimensional stability.BRIEF DESCRIPTION OF DRAWINGS

[0009] FIG. 1 is a schematic cross-sectional view of a wire race bearing;

[0010] FIG. 2 is a schematic cross-sectional view of a damping pad in accordance with a preferable embodiment of the present disclosure;

[0011] FIG. 3 is a schematic view of a manufacturing process of a damping pad in accordance with a preferable embodiment of the present disclosure;

[0012] FIG. 4 is a flow chart illustrating a method for manufacturing a damping pad according to a preferable embodiment of the present disclosure.DETAILED DESCRIPTION

[0013] In order to make the objectives, technical solutions and advantages of the technical solutions of the present disclosure more clear, a clear and complete description will be made hereinafter of the technical solutions of the embodiments of the present disclosure in conjunction with the accompanying drawings of specific embodiments of the present disclosure. Like numbers refer to like parts in the drawings. It is to be noted that the described embodiments are some, but not all, embodiments of the present disclosure. Based on the described embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative labor belong to the scope of protection of the present disclosure.

[0014] Possible embodiments within the scope of the present disclosure may have fewer components, have other components not shown in the figures, different components, differently arranged components, or differently connected components, etc., than the embodiments shown in the figures. Furthermore, two or more components in the figures may be implemented in a single component, or a single component shown in the figures may be implemented as multiple separate components.

[0015] Unless defined otherwise, technical or scientific terms used herein are to be given their ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The terms "first," "second," and the like as used in the description and claims of the disclosed patent application do not denote any order, quantity, or importance, but rather are used merely to distinguish one component from another. Where the number of components is not stated, the number of components may be one or more; Likewise, the articles "a," "an," "the," "said," and the like do not necessarily denote a limitation of quantity. "Comprising" or "comprising" and the like means that the elements or items preceding the word encompass the elements or items listed after the word and their equivalents, but not excluding other elements or items. "Mounted," "disposed," "connected," or "connected," and the like, are not limited to physical or mechanicalmountings, arrangements, connections, but can include electrical mountings, arrangements, connections, whether direct or indirect. "Upper", "lower", "left", "right" and the like are used only to indicate the relative positional relationship when the device is used or the positional relationship shown in the drawings, and when the absolute position of the object to be described is changed, the relative positional relationship may be changed accordingly.

[0016] For ease of explanation, the direction of the axis of rotation of the bearing is referred to herein as the axial direction, and the direction perpendicular to the axial direction is referred to as the radial direction. The term "in / inward" refers to the direction toward the interior of the bearing, and conversely, the term "out / outward" refers to the direction toward the exterior of the bearing. In addition, the same reference numerals are used in different embodiments to refer to components having the same or similar structure and functionality.

[0017] As previously mentioned, a wire race bearing generally comprises: a housing, wires and rolling elements. In different wire race bearings, the respective configuration and form of the housing, the wires, and the rolling elements are different.

[0018] FIG. 1 shows a specific wire race bearing comprising a housing 1, wires 2, damping pads 3, rolling elements 4 etc. The housing 1 may further include a first outer ring housing 11, a second outer ring housing 12, and an inner ring housing 13. The rolling elements 4 are arranged in two rows and the rolling elements are in the form of balls. Each row of rolling elements 4 is further supported by raceway surfaces of the wires 2 arranged diagonally. The wires 2 are received in recesses of the respective housings. Two recesses 130 of the inner ring housing 13 are the in FIG. 1, and the wires 2 in the recesses 130 are in direct contact with the walls of recesses. The first and second outer ring housings 11, 12 comprise recesses 110, 120, respectively, in which the damping pads 3 are disposed, respectively, such that the damping pads 3 are located between the housings and the wires to partially surround the wires 2.

[0019] According to the present disclosure, referring to FIG. 2, the damping pad 3 comprises a reinforcing fiber thread(s) 4 embedded inside the damping pad 3 along the circumferential direction and bonded with the damping pad 3 (as indicated by the dottedcircle in FIG. 2); the reinforcing fiber thread(s) 4 has lower elongation and higher tensile strength relative to the damping pad 3.

[0020] During the extrusion of the damping pad, large deformation occurs due to molecular cross-linking curing of the damping pad material as well as stretching, traction, etc. caused by mechanical forces, and after the reinforcing fiber thread(s) is bonded with the damping pad, the damping pad will be dimensionally stable since the deformation caused by the above factors is prevented even during the extrusion curing process and under the storage conditions. Thus, during the final assembly process of the product, the difficulty of assembly can be reduced based on the correct cut length and the higher dimensional stability.

[0021] In addition, the characteristics of the reinforcing fiber thread(s) may be selected according to different applications of the bearing and other performance requirements of the damping pad. For example, reinforcing fiber thread(s) 4 may have a higher stiffness relative to the damping pad 3. Additionally or alternatively, the reinforcing fiber thread(s) 4 may have a higher bending fatigue resistance relative to the damping pad 3. Additionally or alternatively, the reinforcing fiber thread(s) 4 may have a lower tensile elongation at break relative to the damping pad 3.

[0022] Typically, the damping pad 3 is manufactured by extrusion during which, according to a preferred embodiment of the present disclosure, the reinforcing fiber thread(s) 4 may be embedded in and co-extruded with the damping pad 3.

[0023] Preferably, as shown in FIG. 2, the damping pad 3 has a channel 30 for receiving the wire 2. The reinforcing fiber thread(s) 4 is embedded in the portion where there is a maximum thickness D between the surface 34 of the channel 30 and the outer side 35 of the damping pad (as indicated by the dotted circle at the upper right corner in FIG. 2). More preferably, the ratio of the diameter of the reinforcing fiber thread(s) 4 to this maximum thickness may be 0.3 -0.5.

[0024] It will be appreciated that the reinforcing fiber thread(s) may be embedded at different locations, depending on different requirements and configuration of the damping pad.

[0025] Specifically, the damping pad 3 usually has a first wall 31 and a second wall 32 connected to each other. Thus, it is possible to embed the reinforcing fiber thread(s) 4 inthe connecting portion between the first wall 31 and the second wall 32, and this connecting portion typically corresponds to the portion of the surface 34 of the channel 30 which has a maximum thickness D from the outer side 35 of the damping pad. Additionally or alternatively, a reinforcing fiber thread(s) 4 may be embedded in the edge portion 310 of the first wall 31 (as indicated by the dashed circle at the lower right corner in FIG. 2). Additionally or alternatively, a reinforcing fiber thread(s) 4 may be embedded in the edge portion 320 of the second wall 32 (as indicated by the dashed circle at the upper left corner in FIG. 2). Embedding reinforcing fiber threads at multiple locations may better improve the performance of the damping pad.

[0026] Preferably, the damping pad 3 may be formed by nitrile rubber, butyl rubber, silicone rubber, polyurethane elastomer, styrene butadiene rubber, or neoprene rubber. Thus, the damping pad may have both sufficient elasticity for good damping effect, and good oil resistance, and the like.

[0027] Among the above materials, intrinsic damping property of nitrile rubber (NBR) and butyl rubber (IIR) are the best, while damping property of silicone rubber, polyurethane elastomer (TPU), neoprene (CR), styrene butadiene rubber (SBR) are the moderate.

[0028] Butyl rubber NBR has a large and broad peak of loss factor due to its dense methyl groups, but it has high saturation and poor machinability. The chlorinated butyl rubber has improved molecular polarity and excellent machinability. Since the nitrile rubber has cyano groups with strong polarity, a large secondary force in the molecular chain, and a large loss factor T = tan 8 (damping value), it shows excellent damping property, along with excellent oil resistance, chemical resistance, solvent resistance, and excellent high and low temperatures resistance .

[0029] During loading of the damping rubber, there is a phase difference between the deformation of the rubber and the stress of the rubber, which typically precedes the deformation of the rubber by a phase angle.

[0030] The material used for the damping pad should be near the glass transition region with severe hysteresis and can absorb a large amount of mechanical energy. If the loss peak of the material is higher, the glass transition temperature range is wider, and the temperature range value is more consistent with the external environment, then thedamping effect will be better. In addition, influence factors for the damping performance includes molecular structure, vulcanization, fillers, and blending.

[0031] For a wire race bearing, particularly for a bearing for medical imaging devices such as CT machines, the NBR molecular chain structure contains cyano groups, which have excellent oil resistance and cost efficiency. In contrast, the process cost of CR is higher.

[0032] Preferably, the reinforcing fiber thread(s) 4 may be formed by glass fibers, carbon fibers, aramid fibers, or wire fibers.

[0033] In a preferred embodiment, a glass core thread is formed by twisting 1600 strands of standard glass fibers, so as to be used as the reinforcing fiber thread. A standard glass core thread is 2500 meters per kilogram (3750 feet per pound, 400 tex) with a diameter of 0.5-0.6 mm. The glass fiber filament is a long fiber product, and by making special bonding treatment to high-performance fibers such as the glass fibers, its bonding ability with the NBR rubber will be improved. The types of glass fibers include E-glass, high strength glass. In addition, carbon fibers, aramid fibers and the like may also be used according to different needs. Glass fibers have elasticity rate equivalent to aramid fibers, as well as excellent dimensional stability and bending fatigue resistance. Carbon fibers have elasticity rate equivalent to as steel fibers, as well as advantages like excellent dimensional stability, bending fatigue resistance, and light weight.

[0034] Preferably, the damping pad 3 comprises one or more segments of reinforcing fiber thread 4 embedded in the circumferential direction, that is to say, the reinforcing fiber thread(s) 4 may be embedded in the damping pad 3 along the entire circumference of the damping pad 3, or reinforcing fiber thread(s) 4 may be embedded in the damping pad 3 in segments in the circumferential direction.

[0035] Preferably, the reinforcing fiber thread(s) 4 may be coated externally with adhesive to better bond with the damping pad 3. The adhesive may be Chemlok ® 233X.

[0036] Preferably, the reinforcing fiber thread(s) 4 consists of a plurality of filaments twisted together and also bonded with each other and with the damping pad 3 by means of adhesive.

[0037] Preferably, the damping pad 3 comprises peroxide and sulphur as curing agents, a composite filler system comprising carbon black and white carbon as fillers, plasticizer and / or heavy metal salt as anti -radiati on agent.

[0038] The curing agent may be a combination of peroxide and sulfur. Peroxide curing is a common curing system due to short length of C-C bond and higher bond energy, excellent high temperature resistance, small amount of permanent compression deformation; however, the physical property and mechanical property of the rubber after peroxide curing are poor, and the polysulfide bond (-Sx-) can impart better strength and dynamic property to the rubber, so that the type of cross-linking bond and the cross-linking structure in the rubber are usually adjusted by a method combined with a vulcanization system. Further, when NBR is used for the damping pad, since NBR contains a cyano group in its molecular chain structure, it has excellent oil resistance which is related to the curing system and the plasticizer content, and thus using peroxide and sulfur in combination can minimize the volume change of NBR under high temperature grease environment.

[0039] The type, amount, particle size, and surface activity of the filler will all affect the mechanical property, permanent compression deformation, and damping property of the damping pad. According to the present disclosure, a filler system composed of white carbon (10-20%) and carbon black (30-40%) is used.

[0040] The oil medium may draw soluble complexing agents (e.g., plasticizers, etc.) from the vulcanizate, causing the vulcanizate to shrink or reduce its volume. For bearing applications, a certain temperature threshold for damping (i.e., a temperature range with tan 8 > 0.3) is also required to be met. Therefore, increasing the amount of plasticizer within a certain range can increase the movement ability of the rubber molecules, resulting in increase in the mechanical loss generated under dynamic conditions, thereby increasing the damping performance of the damping pad to a certain extent.

[0041] For medical imaging applications such as CT machines, the effect of radiation on the damping pad is primarily radiation cross-linking or radiation degradation. While heavy metal salts such as barium sulfate, which have high density, can be filled into the damping pad to increase the density of the damping pad, reduce the penetration of radiation, and improve the resistance of the damping pad against radiation.

[0042] In another aspect, the present disclosure also proposes a method for manufacturing the damping pad as described above, comprising:

[0043] Step 1 : performing pre-treatment to the reinforcing fiber thread(s) 4;

[0044] Step 2: introducing the reinforcing fiber thread(s) 4 into an extrusion head for extruding the damping pad 3 to reach an extrusion position corresponding to an embedding position of the reinforcing fiber thread(s) in the damping pad;

[0045] Step 3: co-extruding the damping pad 3 with the reinforcing fiber thread(s) 4 through the extrusion head.

[0046] Preferably, the pre-treatment in step 1 may for example comprise heat treatment, surface pre-treatment, adhesive coating, etc., wherein said heat treatment comprises preheating the reinforcing fiber thread(s) 4 to 200-250°C to remove moisture and facilitate traction under low tension.

[0047] Preferably, in step 2, a guide means 5 and an introduction tube 6 can be provided, see figure 3. The guide means 5 is provided upstream of the extrusion head 7 to introduce the reinforcing fiber thread(s) 4 at a gentle angle into the introduction pipe 6 provided in the extrusion head 7, to introduce the reinforcing fiber thread(s) 4 to the extrusion position. Preferably, a fixed guide means 5 may be a smooth ceramic member, avoiding undesired bending caused by the reinforcing fiber thread(s) 4 passing at a very sharp angle. In addition, the introduction tube 6 may be of sufficient size to allow the reinforcing fiber thread(s) 4 to move through freely and to minimize friction between the reinforcing fiber thread(s) 4 and the introduction tube 6.

[0048] Preferably, for further performance optimization of the already extruded damping pad 3, the method further comprises step 4: performing high temperature setting, microwave vulcanization, and / or hot air vulcanization to the damping pad.

[0049] Referring to FIG. 4, a schematic flow diagram of a method for manufacturing the damping pad according to a preferred embodiment of the present disclosure is shown. At blocks 101 and 102, the reinforcing fiber thread(s) are pre-heated and applied with an adhesive, respectively; at block 103, the damping pad and reinforcing fiber thread(s) are co-extruded from an extrusion head of an extruder; at block 104, the extruded damping pad is subjected to high temperature setting; at block 105, the damping pad is subjected to microwave vulcanization, preferably at a temperature of 240-260°C; at block 106, the damping pad is subjected to a first hot air vulcanization, preferably at a temperature of 230- 250°C; at blocks 107 and 108, the damping pad is subjected to cooling and traction, respectively; at block 109, the damping pad is subjected to a second hot air vulcanization,preferably at a temperature of 220-240°C. To this end, the curing process of the damping pad is substantially complete, followed by cooling and traction of the damping pad at blocks 110 and 111, respectively; at blocks 112, 113 and 114, the damping pad is subjected to coding, traction and rolling operations in sequence.

[0050] While exemplary embodiments of the present disclosure have been described in detail above with reference to preferred embodiments, those skilled in the art will appreciate that many variations and modifications may be made to the specific embodiments described above without departing from the concept of the present disclosure, and that many combinations of the various technical features, structures proposed by the present disclosure may be made without departing from the scope of the present disclosure, which is defined by the appended claims.

Claims

CLAIMS1. A damping pad (3) for a wire race bearing, the wire race bearing comprising a housing (1) and a wire (2), and the damping pad (3) being arranged between the housing (1) and the wire (2) to partially enclose the wire (2); wherein the damping pad (3) comprises a reinforcing fiber thread (4) embedded inside the damping pad (3) in the circumferential direction and bonded with the damping pad (3), the reinforcing fiber thread (4) having a lower elongation rate and a higher tensile strength relative to the damping pad (3).

2. The damping pad (3) of claim 1, characterized in that the damping pad (3) has a channel(30) for accommodating the wire (2), wherein the reinforcing fiber thread (4) is embedded in a portion where there is a maximum thickness between the surface (34) of the channel (30) and the outer side (35) of the damping pad; preferably, the ratio of the diameter of the reinforcing fiber thread (4) to the maximum thickness is 0.3-0.5.

3. The damping pad (3) of claim 1, wherein the damping pad (3) has a first wall (31) and a second wall (32) connected to each other, wherein the reinforcing fiber thread (4) is embedded in the connecting portion between the first wall(31) and the second wall (32); and / or the reinforcing fiber thread (4) is embedded in an edge portion (310) of the first wall (31); and / or the line of reinforcing fibers (4) is embedded in an edge portion (320) of the second wall (32).

4. The damping pad (3) of claim 1, wherein the reinforcing fiber thread (4) has a higher rigidity relative to the damping pad (3); the reinforcing fiber thread (4) has a higher bending fatigue resistance relative to the damping pad (3); and / or the reinforcing fiber thread (4) has a lower tensile elongation at break relative to the damping pad (3).

5. The damping pad (3) of claim 1, wherein the damping pad (3) is manufactured by extrusion process and the reinforcing fiber thread (4) is embedded into and co-extruded with the damping pad (3) during the extrusion process.

6. The damping pad (3) of claim 1, whereinthe damping pad (3) is formed of nitrile rubber, butyl rubber, silicone rubber, polyurethane elastomer, styrene butadiene rubber, or neoprene; and / or the reinforcing fiber thread (4) are formed by glass fibers, carbon fibers, aramid fibers, or wire fibers.

7. The damping pad (3) of claim 1, wherein the damping pad (3) comprises one or more segments of reinforcing fiber thread (4) embedded in the circumferential direction; the reinforcing fiber thread (4) is externally coated with adhesive to bond with the damping pad (3); or the reinforcing fiber thread (4) consists of a plurality strands of filaments twisted together, and the plurality strands of filaments are bonded with each other and with the damping pad (3) by an adhesive.

8. The damping pad (3) according to claim 1, wherein the damping pad (3) comprises peroxide and sulfur as curing agent, carbon black and silica composite filler system as filler, plasticizer and / or heavy metal salt as anti-radiation agent.

9. A method for manufacturing a damping pad (3) as claimed in any one of claims 1-8, comprising: step 1 : performing pre-treatment to the reinforcing fiber thread (4); step 2: introducing the reinforcing fiber thread (4) into an extrusion head for extruding the damping pad (3) to reach an extrusion position corresponding to an embedding position of the reinforcing fiber thread (4) in the damping pad (3); step 3: co-extruding the damping pad (3) with the reinforcing fiber thread (4) through the extrusion head.

10. The method as claimed in claim 9, wherein preferably, the pre-treatment of step 1 comprises: pre-heating the reinforcing fiber thread (4) to 200-250°C and / or applying adhesive to the reinforcing fiber thread (4); preferably, in step 2, a guide means (5) and an introduction pipe (6) are provided, the guide means (5) being provided upstream of the extrusion head (7) to introduce the reinforcing fiber thread (4) at a gentle angle to the introduction pipe (6), the introduction pipe (6) provided in the extrusion head (7), to introduce the reinforcing fiber thread (4) to the extrusion position;preferably, the method further comprises a step 4: subjecting the damping pad (3) to high temperature setting, microwave vulcanization, and / or hot air vulcanization.

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