KR101362832B1 - Core metal for resin welding, composite member and method of manufacturing the same - Google Patents

Abstract

An object of this invention is to provide the resin welding core which can improve the bonding strength of a resin outer peripheral material and a core metal easily, the composite member using the said core, and its manufacturing method.
According to the present invention, by fitting the core 20 to the fitting hole 31 of the resin outer peripheral material 30 and induction heating, the resin outer peripheral material 30 is welded to the circumferential surface 21 of the core 20. When forming, the flat inner wall surface 32 is formed in the fitting hole 31 of the resin outer peripheral material 30, and is formed in the peripheral surface 21 of the core 20 in the direction crossing a peripheral direction, and the peripheral direction By forming a plurality of stripe protrusions 26 and parallel flat portions 25 arranged on both ends of the plurality of stripe protrusions 26 and parallel to the peripheral surface 21 of the core 20. By fitting the fitting hole 31 of the main body 30, the flat inner wall surface 32 is brought into contact with the top portions of the plurality of stripe-shaped protrusions 26, and the flat portions 25 are opposed to each other, and then guided. The resin outer peripheral material 30 is welded to the uneven portion 24 and the flat portion 25 by heating.

Description

Core for resin welding, composite member and manufacturing method thereof {CORE METAL FOR RESIN WELDING, COMPOSITE MEMBER AND METHOD OF MANUFACTURING THE SAME}

The present invention relates to a resin welding core in which a core metal is fitted into a fitting hole of a resin outer material, and the resin outer material is welded to the circumferential surface of the core by induction heating the whole, and a resin welding core (hereinafter, referred to as a core metal). And a composite member in which a resin outer peripheral material is welded and molded on the peripheral surface of the sheet), and a method of manufacturing the composite member.

Conventionally, the composite member which welded the resin outer peripheral material to the circumferential surface of the core is used for various components and apparatus. When the composite member is applied to, for example, a worm wheel of an electric power steering device, it is necessary to securely join the core and the resin outer material in order to secure the handle operation, the durability of the device, and the like. There is.

Conventionally, several techniques have been proposed for welding a resin outer peripheral material to the peripheral surface of the core by fitting the core to the fitting hole of the resin outer material and induction heating. For example, Patent Document 1 below discloses a method of fixing a metal boss to a resin molding. In this method, uneven processing is first performed on the resin contact surface of the metal molded body, that is, the peripheral surface of the core. In the resin molding, a through hole having a smaller diameter than the outer diameter of the metal molded body is formed. The binder is applied to the roughened surface of the metal molded body, the resin molded product is heated to expand the diameter of the through hole, and the metal molded body is pressed into the through hole. Thereafter, the high frequency induction heating causes the metal contact portion of the resin molding to be above the melting temperature to weld the resin molding to the metal molding. According to the method of Cited Reference 1, molded articles such as flat gears and wheels made of resin and metal can be efficiently produced.

Patent Document 2 below describes a method for producing a worm wheel. In this method, first, an outer circumferential uneven portion arranged in the circumferential direction is formed on the outer circumference of the metal core, and an inner circumferential uneven portion arranged in the circumferential direction in a shape corresponding to the outer circumferential uneven portion of the core is formed on the inner circumference of the ring ring made of resin. . An adhesive is interposed between the ring gear and the core, and the outer concave-convex portion and the inner concave-convex portion are engaged, and then bonded by high frequency welding. In the method of Cited Reference 2, it is said that the degree of freedom in design can be improved while securing the fixing force between the metal core and the resin ring gear.

In the conventional technique of fitting the core to the fitting hole of the resin outer material and induction heating, as disclosed in both Patent Literatures 1 and 2, an uneven shape is formed on the circumferential surface of the core and welding between the resin outer material and the core The joining strength by this was improved. For example, in patent document 1, knurling of 1-3 mm etc. is performed in order to improve joining strength. In Cited Reference 2, male serrations are formed on the outer circumference of the metal core to improve the fixing force.

Japanese Patent Application Publication No. 2003-118006 Japanese Patent Application Publication No. 2001-141033

In the conventional method, the joint strength of the resin outer peripheral material with respect to a core was improved by forming the uneven | corrugated shape of a core deeper.

By the way, when forming the uneven | corrugated shape of a core deeply, in order to form the uneven | corrugated shape in a core by knurling, a large pressing force is required by machining at the time of processing, or machining is required. In addition, when forming a big uneven shape in a height (or depth) direction to a core, as described in reference document 2, it can be fitted by forming an uneven shape in the shape corresponding to the uneven shape of the core also in the inner peripheral surface of the resin outer peripheral material. I'm letting you. Therefore, it requires effort to improve the bonding strength of the resin outer material to the core.

Accordingly, the present invention has a first object to provide a resin welding core which can easily improve the bonding strength with the resin outer peripheral material, and to provide a composite member having improved the bonding strength using the core. It is for the second purpose. Moreover, it is a 3rd objective to provide the manufacturing method of the composite member which can easily improve the bonding strength of a core and a resin outer peripheral material.

Even if the core is inserted into the fitting hole of the resin outer material and induction heating, the resin of the resin outer material cannot sufficiently enter the uneven surface of the core, so that the uneven portion of the fine gap between the uneven surface and the resin outer material Occurs. When an unbonded part arises, the bond strength of a core and a resin outer peripheral material falls that much, and the bond strength of the circumferential direction of the resin outer peripheral material with respect to a core, and the bond strength of a central axis direction fall.

In order to increase the joint strength between the core and the resin outer material, when the concave-convex shape of the surface of the core is increased in the height (or depth) direction, the contact gap between the core and the resin outer material is spaced apart in the fitted state before welding. The contact area is reduced. Induction heating in that state prevents the inner circumferential surface of the resin outer peripheral material from being melted uniformly by heat from the core, and increases the unmelted portion or locally overheats, resulting in uneven deformation of the resin. Although the uneven shape is formed on the inner circumferential surface of the resin outer material, the unmelted part or the overheated part occurs at the part where the uneven shape of the core and the uneven shape of the resin outer material do not coincide.

As a result, when the resin outer peripheral material is welded to the core by induction heating while preventing the overheated portion of the resin from occurring, the resin does not enter every corner of the uneven portion of the core, and an unbonded portion is formed on the surface of the uneven portion, and the bonding strength is achieved. It was newly discovered that it could not be improved sufficiently.

In accordance with this knowledge, the resin welding core of the present invention, which achieves the first object, is fitted in the fitting hole of the resin outer peripheral material and induction heated, whereby the resin outer peripheral material is welded to the peripheral surface. And a plurality of stripe-shaped protrusions formed in a direction transverse to each other and arranged in parallel in the circumferential direction, and flat portions respectively provided at both ends of the stripe-shaped protrusions, and adjacent stripe-shaped protrusions when fitting the fitting holes of the resin outer material. A gap is formed between them, and the distance from the central axis of the core to the flat portion is smaller than the distance from the central axis to the top of the stripe-shaped protrusion in the entire circumference.

According to the resin welding core of the present invention, the entire joining surface of the resin outer peripheral material can be melted by the plurality of stripe-shaped protrusions, so that the resin can sufficiently enter the gap between the stripe-shaped protrusions of the core and every corner of the flat portion. have. Therefore, the bonding strength with the resin outer material can be easily improved.

It is particularly preferable that the height of the plurality of stripe protrusions is 1 mm or less, and the gap between adjacent stripe protrusions is 2 mm or less.

It is preferable that the plurality of stripe-shaped protrusions protrude from the flat portion to the outside at a height of 1 mm or less. It is particularly preferable that the width along the central axis of the flat portion of the core is 0.5 to 1 times the maximum spacing in the gap between adjacent stripe protrusions.

The composite member of this invention which achieves a 2nd objective is provided with the above-mentioned resin welding core and the resin outer peripheral material welded to the peripheral surface of this core.

According to this composite member, since the core of the structure mentioned above is used, the joining strength of a core and a resin member can be improved.

This invention which achieves a 3rd objective is a manufacturing method of a composite member which welds a resin outer peripheral material to the circumferential surface of a core by fitting a core to the fitting hole of a resin outer peripheral material, and induction heating, The direction which traverses a circumferential direction And a plurality of stripe-shaped protrusions formed in the circumferential direction and arranged in parallel in the circumferential direction, and a core provided with a flat portion disposed on both end sides of the stripe-shaped protrusions as the peripheral surface, and the resin outer material provided with a flat inner wall surface in the fitting hole. And by fitting the fitting holes of the resin outer peripheral material to the peripheral surface of the core, the flat inner wall face is brought into contact with the tops of the plurality of stripe-shaped protrusions, and the flat portions are opposed to each other. A composite member is manufactured by welding a resin outer periphery between the shape protrusions, the plurality of stripe shape protrusions, and the flat portion.

In this way, when the composite member is manufactured, a flat inner wall surface is provided in the fitting hole of the resin outer material to contact the tops of the plurality of striped projections, so that the part where the striped projections on the flat inner wall surface are in contact with each other is reliably melted. Can be. Then, when the flat inner wall faces between the plurality of stripe protrusions and the plurality of stripe protrusions are sufficiently melted to reach every corner between the stripe protrusions and welded, the flat portion of the core and the resin outer peripheral material are welded. It can also be welded to the inner wall surface, and the flat inner wall surface of the resin outer peripheral material can be bonded to the peripheral surface of the core with sufficient strength. In addition, a plurality of stripe protrusions and flat portions are provided on the circumferential surface of the core, and a flat inner wall surface in contact with the top portions of the stripe protrusions is provided on the resin outer peripheral material to easily improve the bonding strength of the composite member. You can. Therefore, it is not necessary to form the uneven | corrugated shape for fitting in the resin outer peripheral material.

In the manufacturing method of this composite member, it is preferable to space the flat part and the inner wall surface of the resin outer peripheral material so as to face each other by fitting the fitting hole of the resin outer peripheral material to the peripheral surface of the core.

It is particularly preferable that the height of the plurality of stripe protrusions is 1 mm or less, and the gap between adjacent stripe protrusions is 2 mm or less.

It is preferable that the plurality of stripe-shaped protrusions protrude from the flat portion to the outside at a height of 1 mm or less. It is particularly preferable that the width along the central axis of the flat portion of the core is 0.5 to 1 times the maximum spacing in the gap between adjacent stripe protrusions.

In the manufacturing method of this composite member, after the resin outer peripheral material is welded to a core, the cross section is cut, and the part in which the flat part of the core and the resin outer peripheral material were incompletely welded is removed.

According to the resin welding core of the present invention, the peripheral surface includes a plurality of stripe-shaped protrusions and flat portions formed in a direction crossing the peripheral direction, whereby the bonding strength between the peripheral surface of the core and the resin outer peripheral material can be improved. Can provide heart rate.

According to the composite member of the present invention, since the core of the structure described above is used, the composite member having improved bond strength between the core and the resin member can be provided.

According to the manufacturing method of the composite member of the present invention, a plurality of stripe-shaped protrusions and flat portions formed in the direction of crossing the circumferential direction are provided on the peripheral surface of the core, and the flat inner wall surface is provided in the fitting hole of the resin outer material. By induction heating fitting together, the manufacturing method of the composite member which can improve the joining strength of a core and a resin outer peripheral material can be provided.

(A) is a front view which shows the composite member which concerns on embodiment of this invention, a part was shown by the cross section, and (b) is a side view which showed a part of the composite member by the cross section.
Fig. 2A is a front view of the resin welding core according to the embodiment of the present invention, and (b) is a side view showing a part of the resin welding core in cross section.
It is a partial enlarged view which shows the stripe-shaped protrusion of the core for resin welding which concerns on embodiment of this invention.
4 (a) is a cross-sectional view showing a state before the stripe-shaped protrusion of the resin welding core and the resin outer peripheral material are welded, and (b) is the stripe-shaped protrusion of the resin welding core and the resin outer peripheral material. It is sectional drawing which shows the state after welding.
5 (a) to 5 (e) are diagrams illustrating a manufacturing process of the composite member according to the embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to FIGS.

As shown to (a) and (b) of FIG. 1, the composite member 10 of this embodiment forms substantially disk shape centering on the central axis L, the resin welding core 20, and this core The resin outer peripheral material 30 welded to the peripheral surface 21 of 20 is provided. This composite member is an example of a worm wheel blank for electric power steering. The worm wheel blank is an intermediate which can manufacture the worm wheel of an electric power steering apparatus by providing a gear groove in the outer peripheral surface.

As shown in FIGS. 2A, 2B, and 3, the core 20 of the composite member 10 has a substantially disk shape having a predetermined length in the central axis L direction, and has a central axis L at its center. Thus, the through hole 22 formed in a constant cross-sectional shape is formed. One end surface is formed flat, and the other end surface is provided with the hollow part 23 of the annular groove shape. The peripheral surface 21 is formed in parallel along the central axis L, and is formed at both ends in the direction along the central axis L of the concave-convex portion 24 formed in an annular shape over the entire length of the peripheral direction, respectively. It has the flat part 25 formed in circular cross section.

The uneven portion 24 is configured by arranging a plurality of stripe-shaped protrusions 26 formed in a direction crossing the circumferential direction in parallel in the circumferential direction. The plurality of stripe-shaped protrusions 26 are evenly arranged at a constant pitch over the entire circumference.

It is preferable that the shape of each stripe-shaped protrusion part 26 is a shape which is easy to melt resin in the state which contacted the inner surface of the fitting hole 31 of the resin outer peripheral material 30 at the time of induction heating mentioned later, Moreover, after welding, it is preferable to set it as the shape which is easy to ensure the joint strength between the peripheral surface of a core and a resin member. Therefore, it is good to make the shape of many stripe-shaped protrusions 26 the same, and it is preferable to make the shape of all the stripe-shaped protrusions 26 the same.

In this embodiment, all the stripe-shaped projections 26 are formed in the same shape. As shown in Fig. 3, each of the stripe-shaped protrusions 26 has a mountain shape or a substantially triangular shape in which the top portion 26a is narrow and the bottom portion 26b is spread in a sectional shape in the circumferential direction. Both surfaces may be formed in any shape, such as a flat surface or a curved surface. In such a shape, molten resin easily enters the gap 27 between adjacent stripe-shaped protrusions during induction heating described later.

The top portion 26a may be curved or flat, or may have a sharp top. It is preferable that the shape of the bottom part 26b between the adjacent stripe-shaped protrusions 26 is made into a flat or curved surface shape. If it is such a bottom part 26b, molten resin can fully be filled in the bottom part 26b at the time of induction heating.

Both sides of each stripe protrusion 26 may be symmetrical or asymmetrical with respect to the top portion 26a. The gradient of each side is not particularly limited, but the maximum angle θ of each side with respect to the normal of the peripheral surface 21 of the core 20 is, for example, 30 ° to 60 °, preferably 40 ° to 50 °. °. If the maximum angle θ is too small, the gap 27 between the adjacent stripe protrusions 26 becomes deep, and thus, the molten resin becomes difficult to enter the gap 27 during induction heating described later. On the other hand, if the maximum angle θ is too large, the gap 27 between the adjacent stripe protrusions 26 becomes shallow, so that the mechanical engagement force in the circumferential direction between the stripe protrusion 26 and the resin outer peripheral material 30 is applied. It becomes difficult to get

Each striped projection 26 formed in the direction crossing the circumferential direction may be parallel to the central axis L, or may be inclined with respect to the central axis L. FIG. As long as each stripe-shaped protrusion part 26 is a shape parallel to the central axis L, the core 20 can be produced by forging. In addition, although the shape of the direction along the central axis L of each stripe-shaped projection part 26 may be changed in the longitudinal direction, when the core 20 is formed by forging, if the cross section or convex shape is formed over the entire length, Easy to make

It is preferable that the height H of each stripe-shaped projection part 26 is 1 mm or less. The height H of the stripe-shaped projections 26 is the distance from the central axis L to the top portion 26a of each stripe-shaped projection 26 and the bottom portion 26b between the stripe-shaped projections 26 adjacent from the central axis L. It is the difference with the distance to). If the height H of each stripe protrusion 26 is too high, the depth of the gap 27 between adjacent stripe protrusions 26 becomes too deep, and it becomes difficult for molten resin to fully enter. On the other hand, the height H of each stripe-shaped protrusion part 26 becomes like this. Preferably it is 0.5 mm or more, Especially preferably, it is 0.7 mm or more. When the height H of each stripe-shaped protrusion part 26 is too low, it becomes difficult to ensure the mechanical engagement force of the circumferential direction between the core 20 and the resin outer peripheral material, and the direction along the central axis L after welding.

In this uneven part 24, it is preferable to make the clearance gap 27 between adjacent stripe protrusions 26 into 2 mm or less, ie, the maximum space | interval D in the clearance 27 is 2 mm or less. The maximum spacing D in the gap 27 between the adjacent stripe protrusions 26 is a distance along the circumferential direction between the top portions 26a of the adjacent stripe protrusions 26. For example, when the top portion 26a of each stripe protrusion 26 has a sharp top, the distance between the top portions 26a of the stripe protrusion 26 may be approximated in a straight line. When a flat or curved surface is formed at the top portion 26a of the projection portion 26 and the corner portions are formed at both sides, the distance approximated by a straight line between adjacent corner portions between the stripe-shaped projection portions 26 may be sufficient. have. In addition, when the top part 26a of each stripe protrusion part 26 is not curved-shaped, each part may be a distance approximated by the straight line between the site | parts which the resin outer peripheral material 30 mentioned later actually contacts. .

If the gap 27 between adjacent stripe-shaped protrusions 26 is too wide, the heat supplied from each stripe-shaped protrusion 26 to the resin outer peripheral material 30 cannot fully be transmitted at the time of induction heating mentioned later. Therefore, the resin of the resin outer peripheral material 30 which exists in the clearance gap 27 between adjacent stripe protrusions 26 does not melt enough, and a non-bonding part easily arises. On the other hand, if the gap 27 between adjacent stripe-shaped projections 26 is too narrow, the depth of each stripe-shaped projection 26 cannot be deepened, so the protrusion amount is small, and the core and resin outer material 30 after welding are reduced. It becomes difficult to secure sufficient bonding strength between the layers. It is preferable that the maximum spacing D in the gap 27 between adjacent stripe-shaped protrusions 26 is 1 mm or more.

The flat part 25 of the core 20 is formed in the adjoining position of the uneven part 24 in the direction along the center axis L, ie, the position adjoining the both end sides of the many stripe-shaped protrusion part 26. As shown in FIG. The flat portion 25 is made of a surface parallel to the central axis L without irregularities, and preferably made of a curved surface having a circular cross section. The flat part 25 is formed with the distance from the central axis L smaller than the top part 26a of the stripe-shaped protrusion part 26 of the uneven part 24. As shown in FIG. By forming the flat portions 25 at this distance, the top portions of the plurality of striped projections 26 become 1 mm or less in height from the flat portions 25 to the outside. This height becomes like this. Preferably it is 0.5 mm or more, Especially preferably, it is 0.7 mm or more. Therefore, when the flat inner wall surface 32, which will be described later, of the resin outer material 30 is opposed and heated, the resin outer material 30 is welded to the flat part 25 by the heat supplied from the plurality of stripe-shaped protrusions 26. Can be.

The distance from the central axis L of the flat portion 25 is equal to or less than the distance between the bottom portion 26b and the central axis L between the adjacent stripe-shaped protrusions 26, but is preferably the same distance. desirable. Since the resin outer peripheral material 30 is welded to the flat part 25 after welding, the force which is mechanically engaged in the direction along the central axis L between the both ends of each stripe-shaped projection part 26 and the resin outer peripheral material 30 is carried out. Can be obtained, and the bonding strength can be improved.

It is preferable that the width W in the direction along the central axis L of the flat part 25 is formed to be 0.5 times or more of the maximum spacing D in the gap 27 between the adjacent stripe-shaped protrusions 26. When the flat part 25 is formed in such a width, when the site | part adjacent to the edge part of each stripe-shaped projection part 26 softened or melted in induction heating mentioned later, many stripe-shaped projections 26 On both ends, the resin outer peripheral material 30 can be welded to the flat part 25 to a sufficient extent, and along the central axis L between the resin welding core 20 and the resin outer material 30. Mechanical engagement force of the direction can be secured.

The width W of the flat portion 25 may be, for example, equal to or less than the maximum interval D in the gap 27. When the width W of the flat part 25 is too wide, an incomplete welded part may be formed between the flat part 25 and the resin outer peripheral material 30.

The hollow part 23 and the through hole 22 of the core 20 are formed as needed, and the shape and size are arbitrary. In this embodiment, the hollow part 23 is formed in the groove shape opened in one end surface of the core 20, and is set to the depth which reaches inside the bottom part 26b of the uneven part 24. As shown in FIG. Therefore, the thickness between the hollow part 23 and the bottom part 26b of the uneven part 24 becomes thin. If the thickness of this part is thin, heat capacity can be made small and it can heat up easily at the time of heating.

The hollow portion 23 may be a groove formed in each end surface of the core 20, or may be a hole formed locally at a depth reaching one or both end surfaces of the core portion 20 to a position that is inside the uneven portion 24. do. Further, a hole formed locally so as to penetrate between both end surfaces of the core 20 may be used.

Such a core 20 can ensure desired properties, such as the strength required in the use of the composite member obtained, ie, in the case of this embodiment, the use of a worm wheel, and can be comprised from various metals etc. which can be induction-heated. The core 20 may be formed in a unitary shape having a through hole 22, a hollow portion 23, and the like by forging, and having an uneven portion 24 and a flat portion 25.

By using forging, the through hole 22, the hollow portion 23, and the like can be formed without removing the material, so that the material is not wasted. In the case of forging, unlike knurling, the shape, height H, maximum spacing D in the gap 27, position, size, and the like of the plurality of stripe-shaped protrusions 26 can be freely set. Optimum bonding strength of the main material 30 can be ensured. In addition, when the plurality of stripe-shaped protrusions 26 are formed by forging, it is not necessary to press the peripheral surface from the outside to form the uneven portion 24 like knurling, and thus the hollow portion 23 and the uneven portion 24 are formed. Even if the thickness between the bottom portions 26b is thin as in the present embodiment, for example, 5 mm or less, the striped projections 26 can be easily formed on the circumferential surface 21.

The resin outer peripheral material 30 is a resin member welded to the peripheral surface 21 of the core 20. The resin outer peripheral material 30 is made of a thermoplastic resin which can be melted or softened by its heat by heating the core 20 while being placed in contact with the core, and an appropriate material can be selected according to the use of the composite member. Can be. When the fitting hole 31 side is heated above the melting temperature, it is preferable that the surface side is a thermally conductive material that does not melt.

In the present embodiment, polyamides such as 6,6-nylon, 6-nylon and 4,6-nylon are used in order to secure the strength required as the worm wheel and to easily secure the heat resistance. In particular, 6-nylon is preferable for reasons such as the strength can be easily secured, and MC nylon (registered trademark of Nippon Polyphenco Co., Ltd.), which is excellent in mechanical strength, thermal characteristics, and chemical properties, is particularly preferred. desirable. In order to secure the slide mobility, polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polyacetal (POM), or the like may be used.

The resin outer peripheral material 30 of this embodiment has a ring shape. The inner circumferential surface of the resin outer peripheral material 30 is adhered to and adhered to the peripheral surface 21 of the core 20. That is, as shown in FIG.4 (b), the welded resin outer peripheral material 30 completely embeds the many stripe-shaped protrusion part 26 provided in the circumferential surface 21 of the core 20, and resin The outer periphery 30 enters the gap 27 between the respective stripe protrusions 26 and is completely filled to firmly adhere to each stripe protrusion 26, and the flat portion 25 is also sufficiently welded. have.

In the state where the resin outer peripheral material 30 is welded to the core 20 in this manner, since the plurality of stripe-shaped protrusions 26 are completely embedded, the cores visually recognized from both end surfaces of the composite member 10 ( The boundary line between 20) and the resin outer peripheral material 30 is made into the circular shape which consists of the edge part of the flat part 25 as shown in FIG. The outer circumferential shape and the thickness of the resin outer circumferential material 30 have dimensions including a machining allowance such as gear teeth of the worm wheel.

Next, the method of manufacturing the composite member 10 is demonstrated.

In order to manufacture the composite member 10, the preparation process of preparing the resin outer peripheral material 30 and the core 20, and the fitting hole of the resin outer peripheral material 30 in the circumferential surface 21 of the core 20 ( A fitting step of fitting 31) to produce a combination member 40, a welding step of welding the outer peripheral material 30 fitted to the peripheral surface of the core 20 by induction heating of the core 20, and a composite process. There is a pre-processing step for realizing the precision as the member 10.

First, in a preparatory process, as shown to Fig.5 (a), (b), the core 20 and the resin outer peripheral material 30 are formed separately, respectively.

As shown in FIG. 5B, the resin welding core 20 includes a plurality of stripe-shaped protrusions formed on the peripheral surface 21 of the core 20 in a direction crossing the peripheral direction by forging. The uneven portions 24 arranged in parallel in the circumferential direction and the flat portions 25 formed on both end sides of the plurality of stripe-shaped protrusions 26 are formed. The width W along the central axis L of the flat portion 25 is made larger than 0.5 times the maximum spacing D in the gap 27 between the adjacent stripe-shaped protrusions 26.

After forging, machining may be performed as necessary. In machining, both end surfaces and the central axis L are formed at a predetermined right angle, or each portion is formed at a predetermined precision.

The resin outer peripheral material 30 is formed in a ring shape with a thermoplastic resin, as shown to Fig.5 (a). In the present embodiment, the resin outer peripheral material 30 has a fitting hole having an outer circumferential surface 33 of a circular cross section parallel to the central axis L and an inner wall surface corresponding to the circumferential surface 21 of the core 20. 31) and both end surfaces which consist of a plane. The thickness between both end surfaces corresponds to the length in the direction along the central axis L of the uneven portion 24 formed on the circumferential surface 21 of the core 20 and the flat portions 25 on both sides thereof.

The fitting hole 31 is provided with the flat inner wall surface 32 of the circular cross section formed in parallel with the central axis L, without forming an uneven | corrugated shape. The fitting hole 31 may be a through hole or a non-penetrating hole as long as the length in the direction along the central axis L is at least greater than the length in the direction of the central axis of the core uneven portion. In this embodiment, it is formed as a through hole.

The fitting hole 31 is made into a shape in which the tops of as many striped projections as possible, preferably the tops of all the striped projections, are in contact with each other. It is preferable that the inner diameter of the flat inner wall surface 32 of the fitting hole 31 is a dimension which can be fitted to the uneven part 24 of the core 20. Specifically, the inner diameter of the flat inner wall surface 32 is slightly smaller than the maximum diameter constituted by the top portion 26a of the uneven portion 24, and is set smaller by 0.4 to 3%, for example. If the inner diameter of the flat inner wall surface 32 is too large compared to the maximum diameter of the uneven portion 24, during induction heating, which will be described later, the flat inner wall surface 32 may not be sufficiently heated by the heat of the plurality of stripe-shaped protrusions 26. In some cases, the molten resin becomes difficult to sufficiently enter the gap 27 between the adjacent stripe-shaped protrusions 26. On the other hand, if the inner diameter of the flat inner wall surface 32 is too small compared to the maximum diameter of the uneven portion 24, the resin outer peripheral material 30 itself is deformed.

Subsequently, in the bonding step, as shown in FIG. 5C, the fitting holes 31 of the resin outer peripheral material 30 are fitted to the circumferential surface 21 of the core 20. As shown in Fig. 2), the flat inner wall surface 32 is brought into contact with the tops of the plurality of stripe-shaped protrusions 26, and the flat portions 25 are opposed to each other. The gap is formed between the adjacent stripe-shaped protrusions 26 by fitting the core 20 into the fitting hole 31 of the resin outer peripheral material 30.

In order to fit the core 20, for example, the resin outer peripheral material 30 may be thermally expanded to fit the peripheral surface 21 of the core 20. For example, the resin outer peripheral material 30 is heated by a heating furnace or the like, and the diameter of the fitting hole 31 is expanded so as to be a diameter corresponding to the outer diameter of the core 20. The core 20 can be inserted easily.

Heating temperature can be set according to the inner diameter of the fitting hole 31 with respect to the outer diameter of the core 20, the kind of thermoplastic resin, the softening point, the expansion ratio, and the like. For example, in the case of polyamide, it is preferable to set it as about 130-150 degreeC. And when heating temperature is too high, the shape precision of the resin outer peripheral material 30 may fall, and when too low, the insertion of the resin outer peripheral material 30 will require effort.

The fitting between the peripheral surface 21 of the core 20 and the fitting hole 31 of the resin outer peripheral material 30 is performed by a press or the like, for example, by using a jig or the like to perform parallelism or shim fitting. Pressing in the axial direction can be inserted. In this way, the combination member 40 which combined the core 20 and the resin outer peripheral material 30 is produced.

And in order to improve the bonding strength between the core 20 and the resin outer peripheral material 30 before this bonding process, the fitting hole of the circumferential surface 21 of the core 20 and the resin outer peripheral material 30 ( One or both of 31) may be provided with a bonding force improving agent layer such as various adhesive materials.

Subsequently, in the welding step, as shown in FIG. 5D, the resin outer peripheral material 30 is welded to the uneven portion 24 and the flat portion 25 of the core 20 by induction heating. This welding process is performed using the apparatus which can raise the core 20, but in this embodiment, a high frequency induction heating apparatus is used. In this apparatus, a heating coil 50 for generating an alternating magnetic field is provided, and the peripheral surface of the core 20 can be adjusted to a desired temperature by controlling power feeding to the heating coil 50. It is supposed to be done. In addition, at the time of heating, the combination member 40 and the heating coil 50 can be rotated relatively about the central axis L. As shown in FIG.

At the time of heating, induction heating of the core 20 is made by flowing a high frequency current through the heating coil 50, and the surface temperature of the core 20 is maintained in the temperature range more than the melting temperature of resin which comprises the resin outer peripheral material 30. . For example, when melt temperature 200-240 degreeC resin is used, it maintains at 20 degreeC-60 degreeC higher than melting temperature.

Thereby, the part of the resin outer peripheral material 30 which contacts the stripe-shaped protrusion part 26 of the circumferential surface 21 of the core 20, and its adjacent part are heated up by the heat of the core 20, and it softens or melts. As a result, the resin between the adjacent stripe protrusions 26 is melted and enters the gap 27 between the stripe protrusions 26 so that the molten resin is in close contact with the uneven portion 24. In addition, the resin softened or melted in the vicinity of the plurality of stripe-shaped protrusions 26 in the resin outer peripheral material 30 is in close contact with the flat portion 25 of the core 20.

In this melting step, the plurality of combination members 40 may be supported by the axial jig, and the plurality may be combined to inductively heat. For example, the axial jig can be fixed by penetrating the inside of the through hole 22 of each of the cores 20, and the movable coil 50 can be moved relative to the heating coil 50 in this state.

After the welding step, for example, heat radiation in the air or cooling with a cooling liquid causes the molten resin to solidify in a state in which the molten resin is in close contact with the peripheral surface of the core 20.

In this embodiment, a preprocessing process is performed after that. In the pre-processing step, the end face of the resin outer peripheral material 30 and the end face of the core 20 are machined, for example, into a planar shape. Here, as shown in FIG. 5E, the cross section is cut to narrow the width W along the central axis L of the flat portion 25. The amount of cutting the cross section can be appropriately adjusted, but is, for example, less than or equal to the maximum distance D in the gap 27 between the adjacent stripe protrusions 26. This removes incompletely welded portions of the flat portion 25 and the resin outer peripheral material 30 of the core 20, and extends the flat portion 25 and the resin outer peripheral material 30 to both ends over the entire circumference. It can be made completely welded. By processing, the width W of the flat portion 25 may be 0.5 to 1 times the maximum spacing D in the gap 27. When the width W of the flat part 25 is made too narrow, the engagement force of the direction along the central axis L of the core 20 and the resin outer peripheral material 30 may fall.

In this pre-processing process, for example, the precision of each part, such as the precision of the through-hole 22, the parallelism of the outer peripheral surface of the resin outer peripheral material 30 with respect to the central axis L, the orthogonality of both cross sections, etc., is processed to a predetermined range. It is preferable.

Thereby, manufacture of the composite member 10 as shown in FIG. 1 is complete | finished.

Thus, when the key groove is formed in the through-hole 22 with respect to the composite member 10 obtained in this way, and the desired tooth part etc. are processed to the outer periphery of the resin outer peripheral material 30 with good precision, the worm wheel which is a final product will be manufactured. Can be.

When the composite member 10 is manufactured as mentioned above, the resin outer peripheral material 30 which contacts each heated stripe-shaped projection part 26 melts, and the molten resin gaps between each stripe-shaped projection part 26 are carried out. It can enter to every corner inside (27) reliably. Therefore, the non-bonding part can be prevented from occurring, and the resin outer peripheral material 30 can be reliably welded to the circumferential surface 21 of the core 20.

In addition, when the fitting hole 31 of the resin outer peripheral material 30 is fitted to the circumferential surface 21 of the core 20 and induction heating, the uneven portion 24 is formed by each of the heated stripe-shaped protrusions 26. The resin outer peripheral material 30 at the position adjacent to) and the resin outer peripheral material 30 at the position of the both ends adjacent to the uneven part 24 are melted. Therefore, molten resin enters into the gap 27 between the stripe protrusions 26, and each stripe protrusion 26 and the resin outer peripheral material 30 are welded, and each stripe protrusion 26 is formed. The molten resin reaches the flat part 25 in the adjacent position of the both ends side of the, and the flat part 25 and the resin outer peripheral material 30 are welded. Thereby, the uneven part 24 whole is embedded in the resin outer peripheral material 30, and is fixed firmly.

After welding the resin outer peripheral material 30, the uneven part 24 is not visually recognized from the both end surfaces of the core 20, and the outstanding external appearance can be obtained. In addition, by welding the plurality of stripe-shaped protrusions 26 to the resin outer peripheral material 30, the bonding strength due to welding is improved, and between the side surfaces of the plurality of stripe-shaped protrusions 26 and the respective stripe-shaped protrusions 26. A mechanically engaging force in the circumferential direction can be obtained between the resins contained in the resin, and mechanically in the direction along the central axis L between both ends of the plurality of stripe-shaped protrusions 26 and the resin on the flat portion 25. You can gain the power to be engaged. Therefore, the resin outer peripheral material 30 can be welded to the core 20 with sufficient strength.

In addition, in this core 20, the width W of the flat part 25 is set to 0.5 times or more of the maximum space | interval D in the clearance gap 27 between adjacent stripe protrusions 26. As shown in FIG. When the resin outer peripheral material 30 disposed between the adjacent striped projections 26 by heat of each stripe protrusion 26 at the time of welding is heated enough to melt | dissolve, the stripe protrusion of the resin outer peripheral material 30 is heated. The vicinity of the site of contact with (26) is also melted. Therefore, the resin sufficiently melted adjacent to the striped projection 26 of the resin outer peripheral material 30 can be reliably bonded to the flat portion 25 of the core 20, whereby the core 20 and the resin Sufficient joint strength with the main material 30 can be ensured.

In particular, the width W along the central axis L of the flat portion 25 is formed to be larger than 0.5 times the maximum spacing D in the gap 27 between the adjacent stripe-shaped protrusions 26, and the peripheral surface of the core 20 After welding the resin outer peripheral material 30 to 21, the cross section is cut | disconnected so that the width | variety of the flat part 25 of the core 20 may be narrowed.

Therefore, at the time of welding, both ends of the resin outer peripheral material 30 can be melted sufficiently in the wide flat part 25, and can be reliably welded to the flat part 25. As shown in FIG. In addition, since the end surface of the core 20 is cut after welding, the composite member 10 in which the resin outer peripheral material 30 and the core 20 are fully welded to the edge part can be obtained.

Therefore, in such a manufacturing process, it is not necessary to form the uneven | corrugated shape of the uneven part 24 of the core 20 largely, nor is it necessary to form the uneven | corrugated shape in the inner surface of the resin outer peripheral material 30. Therefore, the bonding strength of the core 20 and the resin outer peripheral material 30 can be improved easily. Hereinafter, an Example and a comparative example are demonstrated.

[Example]

The resin welding core 20 as shown in FIG. 2 is produced, the ring-shaped resin outer peripheral material 30 corresponding thereto is fitted to the peripheral surface of the core 20, and welded by high frequency induction heating. The composite member was produced.

The resin welding core 20 is made of carbon steel, has a maximum diameter of 60 mm and a thickness of 16 mm, and a 2 mm flat portion 25 is provided at both ends on the circumferential surface 21 and traverses the circumferential direction between the flat portions. A plurality of stripe-shaped protrusions 26 formed in the direction to be arranged are arranged in parallel in the circumferential direction. The cross-sectional shape of each stripe-shaped protrusion part 26 in the circumferential direction made a substantially triangular shape, and the angle of the top part 26a was set to approximately 90 degrees symmetrically with respect to the normal line from the central axis L. The height of each stripe-shaped projection 26 was 0.9 mm, and the maximum distance D in the gap between adjacent stripe-shaped projections 26 was 1.9 mm. On the other hand, the resin outer peripheral material 30 is a molded body made of MC nylon (manufactured by Japan Polyphenco, Inc., registered trademark), the outer diameter is 85 mm, the inner diameter of the fitting hole 31 is 60 mm, and the thickness is 19 mm. Induction heating controlled the feeding to the coil so that the surface temperature of the core 20 became an almost melting temperature of the resin constituting the resin outer peripheral material 30.

The obtained composite member 10 was cut in the direction of the central axis, and the cross section of the bottom portion 26b between the adjacent stripe-shaped protrusions 26 was observed. Was confirmed to be welded. In addition, in the Example, it was confirmed that the resin of the resin outer peripheral material 30 fully exists in the position of the said bottom part 26b, and the bottom part 26b is fully welded.

Next, six composite members 10 are fabricated in the same manner as described above, and the load is applied to the core 20 and the resin outer peripheral material 30 so as to be in the opposite direction along the central axis L, thereby yielding strength. Yield strength was measured. As a result, the maximum value was 85.9 kN, the minimum value was 62.3 kN, and the average value was 75.2 kN.

(Comparative Example 1)

The height of each stripe protrusion of the core was made larger than 1 mm, and the maximum spacing D in the gap 27 between adjacent stripe protrusions 26 was designed to be larger than 2 mm. Otherwise, all were performed similarly to Example, and the composite member was produced.

According to the comparative example 1, the obtained composite member 10 was cut | disconnected in the center axis direction, and the cross section of the bottom part 26b position between adjacent stripe protrusions 26 was observed. In particular, there were many fine beauty wearing points especially on the bottom 26b side.

In addition, six composite members 10 were fabricated, and a load was applied to the core 20 and the resin outer peripheral material 30 so as to be in the opposite direction along the central axis L, and the yield strength was measured. As a result, the maximum value was 40.3 kN, the minimum value was 30.0 kN, and the average value was 34.2 kN. It was confirmed that the yield strength was inferior to that of the example.

10: composite member 20: core for resin welding
21: circumference of the core 22: through hole
23: hollow portion 24: uneven portion
25: flat part 26: stripe protrusion
26a: top part 26b: bottom part
27: gap 30: resin outer material
31: fitting hole 32: flat inner wall surface
33: outer peripheral surface 40: combination member
50: heating coil L: central axis
H: height W: width

Claims (11)

In a core metal in which the resin outer peripheral material is welded to the peripheral surface by being fitted into the fitting hole of the resin outer material and induction heating,
The circumferential surface includes a plurality of stripe-shaped protrusions formed in a direction crossing the circumferential direction and arranged in parallel in the circumferential direction, and flat portions formed on both end sides of the stripe-shaped protrusions,
A gap is formed between the stripe protrusions adjacent to each other when fitted to the fitting hole of the resin outer peripheral material.
The core from the central axis of the core to the flat portion is smaller than the distance from the central axis to the top of the stripe-shaped protrusion in the entire circumference. The method of claim 1,
The height of the said plurality of stripe-shaped projections is 1 mm or less, and the gap between adjacent stripe-shaped projections is 2 mm or less. The method of claim 1,
The plurality of stripe-shaped projections protrude from the flat portion to the outside at a height of 1 mm or less, and the core is formed. The method of claim 1,
The core according to claim 1, wherein the width along the central axis of the flat portion of the core is made 0.5 to 1 times the maximum spacing in the gap between adjacent stripe protrusions. The core according to any one of claims 1 to 4; And
Resin outer material welded to the peripheral surface of the core
Composite member comprising a. As a manufacturing method of the composite member which welds the said resin outer peripheral material to the circumferential surface of the said core by fitting a core to the fitting hole of a resin outer peripheral material, and induction heating,
A plurality of stripe-shaped protrusions formed in a direction crossing the circumferential direction and arranged in parallel in the circumferential direction and flat portions disposed at both ends of the stripe-shaped protrusions are prepared in the core,
Preparing the resin outer peripheral material having a flat inner wall surface formed in the fitting hole;
By fitting the fitting hole of the resin outer peripheral material to the peripheral surface of the core, the flat inner wall surface is brought into contact with the tops of the plurality of stripe-shaped protrusions and opposes the flat portion,
The induction heating is followed by welding the resin outer peripheral material to the plurality of striped projections and the flat portion of the core. The method according to claim 6,
The manufacturing method of the composite member which spaces and opposes the said flat part and the inner wall surface of the said resin outer peripheral material by fitting the fitting hole of the said resin outer peripheral material to the circumferential surface of the said core. The method according to claim 6,
The height of the said some stripe-shaped projection part is 1 mm or less, and the clearance gap between the adjacent stripe-shaped protrusion parts is 2 mm or less, The manufacturing method of the composite member. The method according to claim 6,
The plurality of stripe-shaped protrusions protrude from the flat portion to the outside at a height of 1 mm or less, and the manufacturing method of the composite member. The method according to claim 6,
The manufacturing method of the composite member which makes the width | variety of the said flat part 0.5 times or more of 1 time or less of the maximum space | interval in the space | interval between the adjacent stripe protrusions. The method according to claim 6,
A method for producing a composite member, wherein after welding the resin outer peripheral material to the core, a cross section is cut to remove a portion where the flat portion of the core and the resin outer peripheral material are incompletely welded.

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