Plastic-coated bearing and manufacturing method thereof

Abstract

The present invention belongs to the field of bearings, and specifically relates to a plastic-coated bearing and a method for manufacturing the same. By designing the wheel body of the plastic-coated bearing to have a structure comprising a first plastic body and a second plastic body, the first plastic body and the second plastic body can be injection-molded twice, so that the amount of glue used in the first injection molding of the first plastic body is relatively small, which can effectively avoid excessive shrinkage of the mounting hole (over-extrusion of the bearing) during the cooling process of the first plastic body. Furthermore, when the first plastic body is injection-molded alone, the first plastic body can be injection-molded into a denser structure first, thereby improving the hardness, impact resistance, and friction resistance of the plastic-coated bearing wheel body. The second plastic body is designed to be coated outside the first plastic body, further allowing the bearing, the first plastic body, and the second plastic body to form a plastic-coated bearing with a stable and strong structure.

Description

Technical Field

[0001] The invention belongs to the field of door and window hardware accessories, and particularly relates to a plastic-coated bearing and a manufacturing method thereof. Background Art

[0002] Plastic-coated bearings are typically coated with a layer of plastic, typically made of nylon (PA), polyoxymethylene (POM), or engineering plastics (PP). This coating provides a certain degree of hardness, impact resistance, friction resistance, and self-lubrication. Plastic-coated bearings are widely used in machinery, industrial assembly lines, furniture, and hardware. Depending on the application, plastic-coated bearings can be manufactured in various shapes, such as grooved pulleys and rollers.

[0003] Existing overmolded bearings are manufactured using an injection molding process to create an outer plastic layer directly on the bearing. Increasing the injection pressure can make the outer plastic layer denser (higher density), thereby improving its hardness, impact resistance, and friction resistance. However, excessive injection pressure increases the amount of plastic injected into the outer plastic layer. This increased injection volume causes the outer plastic layer to shrink excessively during cooling, squeezing the bearing and causing it to stick or lock. Therefore, it is difficult to improve the hardness, impact resistance, and friction resistance of the outer plastic layer of existing overmolded bearings. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a plastic-coated bearing and a manufacturing method thereof in response to the above-mentioned defects of the prior art, so as to solve the defects of the existing plastic-coated bearings in that the hardness, impact resistance, friction resistance and other properties of the outer plastic layer are difficult to improve.

[0005] The technical solution adopted by the present invention to solve the technical problem is: to provide a plastic-coated bearing, comprising a bearing and a wheel body arranged outside the bearing, wherein the wheel body comprises:

[0006] a first plastic body, wherein a mounting hole is formed on the first plastic body, and the bearing is fixed to the mounting hole;

[0007] A second plastic body is covered on the outside of the first plastic body.

[0008] A further preferred embodiment of the present invention is that one or more auxiliary holes are formed on the first plastic body, and the auxiliary holes penetrate the first plastic body; the second plastic body includes a filling portion for filling the auxiliary holes and a covering portion covering the first plastic body.

[0009] A further preferred solution of the present invention is that the auxiliary hole is connected to the mounting hole on the hole wall of the mounting hole.

[0010] A further preferred solution of the present invention is that the auxiliary hole completely penetrates the hole wall of the mounting hole in the axial direction, so that the hole wall of the mounting hole forms a broken hole wall section or multiple hole wall sections spaced apart from each other.

[0011] A further preferred solution of the present invention is that a convex ring is provided in the middle of the outer side of the first plastic body, an annular track groove is provided on the outer side of the second plastic body, and the convex ring is located at the bottom of the annular track groove.

[0012] A further preferred embodiment of the present invention is that a concave and convex anti-slip structure is provided between the outer side surface of the first plastic body and the second plastic body.

[0013] A further preferred embodiment of the present invention is that the anti-slip structure includes an annular groove provided on the outer side of the first plastic body and symmetrically arranged about the annular protrusion, and an annular clamping ring provided on the second plastic body and clamped in the annular clamping groove.

[0014] A further preferred solution of the present invention is that a plurality of bosses are formed on the end of the first plastic body, and the second plastic body further fills the areas between the bosses.

[0015] A further preferred solution of the present invention is that the end surface of the boss is flush with the surface of the second plastic body filling the area between the bosses.

[0016] Another technical solution adopted by the present invention to solve the technical problem is to provide a method for manufacturing a plastic-coated bearing, comprising the following steps:

[0017] injection molding a first plastic body to form a mounting hole on the first plastic body;

[0018] Fixing the bearing into the mounting hole;

[0019] A second plastic body is injection-molded so that the second plastic body covers the first plastic body.

[0020] A further preferred embodiment of the present invention is that when the first plastic body is injection molded, one or more auxiliary holes are formed on the first plastic body, and the auxiliary holes penetrate the first plastic body; when the second plastic body is injection molded, the second plastic body fills the one or more auxiliary holes.

[0021] A further preferred solution of the present invention is that when the first plastic body is injection-molded, the auxiliary hole is also made to penetrate the mounting hole on the hole wall of the mounting hole.

[0022] The present invention has the beneficial effect of designing the wheel body of the overmolded bearing to have a structure comprising a first plastic body and a second plastic body. These first and second plastic bodies can be injection molded in two stages, resulting in a smaller amount of glue during the first injection molding of the first plastic body. This effectively prevents excessive shrinkage of the mounting hole (over-squeezing the bearing) during the cooling process of the first plastic body. Furthermore, when the first plastic body is injection molded separately, it can be molded into a denser structure, thereby improving the hardness, impact resistance, and friction resistance of the overmolded bearing wheel body. By designing the second plastic body to cover the first plastic body, the bearing, first plastic body, and second plastic body further form a stable and sturdy overmolded bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0024] Figure 1 1 is a schematic diagram of the three-dimensional structure of a plastic-coated bearing according to the first embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the exploded structure of the plastic-coated bearing according to the first embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the three-dimensional structure of the first plastic body of the first embodiment of the present invention;

[0027] Figure 4 1 is a schematic diagram of the cross-sectional structure of the first plastic body according to the first embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the three-dimensional structure of the second plastic body in Example 1 of the present invention;

[0029] Figure 6 1 is a schematic cross-sectional structural diagram of a second plastic body according to a first embodiment of the present invention;

[0030] Figure 7 Schematic diagram of the cross-sectional structure of the plastic-coated bearing according to the first embodiment of the present invention. DETAILED DESCRIPTION

[0031] Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0032] Example 1

[0033] like Figure 1 、 2As shown, the overmolded bearing of this embodiment includes a bearing 1 and a wheel body 2 disposed outside the bearing 1, wherein the wheel body 2 includes a first plastic body 21 and a second plastic body 22. A mounting hole 211 is formed on the first plastic body 21, and the bearing 1 is fixed to the mounting hole 211; the second plastic body 22 is coated on the outside of the first plastic body 21. By designing the wheel body 2 of the overmolded bearing to have a structure with a first plastic body 21 and a second plastic body 22, the first plastic body 21 and the second plastic body 22 can be injection molded twice, so that the amount of glue is less when the first plastic body 21 is injected for the first time, which can effectively prevent the first plastic body 21 from shrinking excessively (over-squeezing the bearing 1) due to excessive shrinkage during the cooling process. Furthermore, when the first plastic body 21 is injected separately, the first plastic body 21 can be injected into a denser structure first, thereby improving the hardness, impact resistance, and friction resistance of the overmolded bearing wheel body 2. The second plastic body 22 is designed to cover the first plastic body 21, further ensuring that the bearing 1, the first plastic body 21, and the second plastic body 22 form a structurally stable and sturdy plastic-coated bearing. The plastic-coated bearing structured in this manner not only improves the hardness, impact resistance, and friction resistance of the plastic-coated bearing wheel 2 through the first plastic body 21, but also reduces the amount of plastic in the first plastic body 21 by replacing the existing monolithic outer plastic layer with two plastic bodies, the first plastic body 21 and the second plastic body 22, thereby preventing the bearing 1 from locking or sticking due to excessive shrinkage of the first plastic body 21.

[0034] like Figure 2 As shown, one or more auxiliary holes 212 are also formed on the first plastic body 21, and the auxiliary holes 212 pass through the first plastic body 21; the second plastic body 22 includes a filling portion 221 that fills the auxiliary holes 212 and a covering portion 222 that covers the outside of the first plastic body 21. The provision of the auxiliary holes 212 can, on the one hand, further reduce the amount of glue in the first plastic body 21, and on the other hand, serve as a glue flow channel when injecting the second plastic body 22. After the second plastic body 22 is formed, its filling portion 221 is embedded in the auxiliary holes 212, and the two ends of the filling portion 221 are respectively connected to the covering portion 222 that covers the outside of the first plastic body 21, so that the bearing 1, the first plastic body 21, and the second plastic body 22 form a structurally stable and strong plastic-coated bearing. Furthermore, the auxiliary holes 212 pass through the mounting hole 211 on the hole wall of the mounting hole 211. Preferably, the auxiliary hole 212 is completely connected with the hole wall of the mounting hole 211 in the axial direction, so that the hole wall of the mounting hole 211 forms a broken hole wall or multiple hole walls spaced apart from each other ( Figure 2Because the first plastic body 21 has a mounting hole 211 and one or more auxiliary holes 212 extending through the mounting hole 211 on the wall of the mounting hole 211, the mounting hole 211 has a certain degree of elastic expansion and contraction properties. This allows the bearing 1 to be fixed to the mounting hole 211 after the first plastic body 21 is formed, thereby preventing the bearing 1 from becoming stuck or locked when the first plastic body 21 cools and contracts.

[0035] like Figure 3-7 As shown, a convex ring 213 is provided in the middle of the outer side surface of the first plastic body 21, and an annular track groove 223 is provided on the outer side of the second plastic body 22, and the convex ring 213 is located at the bottom of the annular track groove 223. A concave and convex anti-slip structure 23 is provided between the outer side surface of the first plastic body 21 and the second plastic body 22. The provision of the anti-slip structure 23 can make the combination of the first plastic body 21 and the second plastic body 22 more stable, and prevent the second plastic body 22 from cracking or detaching from the first plastic body 21 when the overmolded bearing runs on the track. Preferably, the anti-slip structure 23 includes an annular groove 231 provided on the outer side surface of the first plastic body 21 and symmetrically arranged about the convex ring 213, and an annular retaining ring 232 provided on the second plastic body 22 and clamped in the annular groove 231. The annular grooves 231 are symmetrically arranged on both sides of the convex ring 213, so that when the overmolded bearing runs on the track, the track will keep the annular retaining ring 232 on the second plastic body 22 squeezed into the annular groove 231, further preventing the second plastic body 22 from cracking or separating from the first plastic body 21. It should be noted that the convex ring 213 is located at the bottom of the annular track groove 223, including the case where the convex ring 213 is exposed in the annular track groove 223, and also includes the case where the convex ring 213 is not exposed (i.e., the groove wall of the annular track groove 223 is completely formed by the second plastic body 22). When the convex ring 213 is exposed in the annular track groove 223, the overmolded bearing can abut the track when running on the track, and take advantage of the excellent hardness, impact resistance and friction resistance of the first plastic body 21 to bear most of the force from the track. When the convex ring 213 is not exposed in the annular track groove 223 (not shown in the figure), when the over-molded bearing runs on the track, the annular track groove 223 receives the force from the track and transmits it to the convex ring 213 through the bottom wall of the annular track groove 223. At this time, the convex ring 213 (the first plastic body 21) can act as an internal support skeleton.

[0036] like Figure 3-7The first plastic body 21 is formed with a plurality of bosses 214 at its end, and the second plastic body 22 also fills the areas between the bosses 214. The end surfaces of the bosses 214 are flush with the surface of the second plastic body 22 that fills the areas between the bosses 214. Specifically, the covering portion 222 partially fills the areas between the bosses 214, and the covering portion 222 is formed with holes 224 corresponding to the bosses 214. The arrangement of the bosses 214 creates grooves between adjacent bosses 214, thereby reducing the amount of glue used in the injection molding of the first plastic body 21 and further preventing excessive shrinkage of the first plastic body 21 during cooling. Furthermore, the arrangement of the bosses 214 allows the covering portion of the second plastic body 22 to partially fill the grooves formed between adjacent bosses 214 during the injection molding of the second plastic body 22, thereby achieving a tighter bond between the second plastic body 22 and the first plastic body 21.

[0037] Example 2

[0038] This embodiment provides a method for manufacturing the plastic-coated bearing of embodiment 1, comprising the following steps:

[0039] S1 injects the first plastic body 21 to form a mounting hole 211 on the first plastic body 21; S2 fixes the bearing 1 into the mounting hole 211; S3 injects the second plastic body 22 to cover the first plastic body 21. The injection molding is performed in two steps, so that the amount of glue used in the first injection molding of the first plastic body 21 is less, which can effectively prevent the first plastic body 21 from shrinking excessively (over-squeezing) during the cooling process, resulting in the mounting hole 211 being excessively reduced (over-extruding the bearing 1). Furthermore, when the first plastic body 21 is injection molded alone, the first plastic body 21 can be injection molded into a denser structure first, thereby improving the hardness, impact resistance, and friction resistance of the overmolded bearing wheel body 2. The second plastic body 22 is designed to cover the outside of the first plastic body 21, further allowing the bearing 1, the first plastic body 21, and the second plastic body 22 to form a structurally stable and strong overmolded bearing. Furthermore, when the first plastic body 21 is injection-molded, one or more auxiliary holes 212 are formed in the first plastic body 21. These auxiliary holes 212 extend through the first plastic body 21. When the second plastic body 22 is injection-molded, the second plastic body 22 fills the one or more auxiliary holes 212. Preferably, when the first plastic body 21 is injection-molded, the auxiliary holes 212 are formed on the wall of the mounting hole 211 and communicate with the mounting hole 211. Forming one or more auxiliary holes 212 in the first plastic body 21 further reduces the amount of glue applied to the first plastic body 21 and serves as a glue flow channel when the second plastic body 22 is injection-molded. Filling the one or more auxiliary holes 212 with the second plastic body 22 ensures that the bearing 1, the first plastic body 21, and the second plastic body 22 form a structurally stable and sturdy overmolded bearing. Furthermore, since the first plastic body 21 has a mounting hole 211 and one or more auxiliary holes 212 on the hole wall of the mounting hole 211 that penetrate the mounting hole 211, the mounting hole 211 has certain elastic expansion and contraction properties, so that the bearing 1 can be fixed to the mounting hole 211 after the first plastic body 21 is formed, avoiding the bearing 1 from getting stuck or locked when the first plastic body 21 cools and shrinks.

[0040] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Those skilled in the art may modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein; and all these modifications and replacements should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A plastic-coated bearing comprising a bearing and a wheel disposed outside the bearing, characterized in that: The wheel body includes: a first plastic body, a mounting hole is formed on the first plastic body, and the bearing is fixed to the mounting hole; a second plastic body, and the second plastic body is covered outside the first plastic body; One or more auxiliary holes are further formed on the first plastic body, and the auxiliary holes penetrate the first plastic body; the second plastic body includes a filling portion filling the auxiliary holes and a covering portion covering the first plastic body; The auxiliary hole is on the hole wall of the mounting hole and is connected to the mounting hole; The auxiliary hole completely penetrates the hole wall of the mounting hole in the axial direction, so that the hole wall of the mounting hole forms a broken hole wall or multiple hole wall sections spaced apart from each other; A convex ring is provided at the middle of the outer side surface of the first plastic body, and an annular track groove is provided on the outer side of the second plastic body. The convex ring is located at the bottom of the annular track groove.

2. The plastic-coated bearing according to claim 1, characterized in that: A concave-convex anti-slip structure is provided between the outer side surface of the first plastic body and the covering portion.

3. The plastic-coated bearing according to claim 2, characterized in that: The anti-slip structure includes an annular groove provided on the outer side of the first plastic body and symmetrically arranged about the convex ring, and an annular clamping ring provided on the covering portion and clamped in the annular groove.

4. The plastic-coated bearing according to claim 1, characterized in that: A plurality of bosses are formed on the end surface of the first plastic body, and the covering portion further fills the areas between the bosses.

5. The plastic-coated bearing according to claim 4, characterized in that: The end surface of the boss is flush with the outer surface of the covering portion filling the area between the bosses.

6. The plastic-coated bearing according to claim 1, characterized in that: The first plastic body and the second plastic body are made of the same plastic, and the density of the first plastic body is greater than that of the second plastic body.

7. A method for manufacturing a plastic-coated bearing, characterized in that: The following steps are involved: Injection-molding a first plastic body to form a mounting hole on the first plastic body; fixing the bearing into the mounting hole; and injection-molding a second plastic body so that the second plastic body covers the first plastic body; When the first plastic body is injection-molded, one or more auxiliary holes are formed on the first plastic body, and the auxiliary holes penetrate the first plastic body; when the second plastic body is injection-molded, the second plastic body fills the one or more auxiliary holes; When the first plastic body is injection-molded, the auxiliary hole is also formed on the hole wall of the mounting hole to communicate with the mounting hole; The auxiliary hole completely penetrates the hole wall of the mounting hole along the axial direction, so that the hole wall of the mounting hole forms a broken hole wall section or multiple hole wall sections spaced from each other.

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