JP4962611B2 - Resin-welded core, composite member and manufacturing method thereof - Google Patents

Description

  The present invention relates to a resin welding core metal in which a resin outer peripheral material is welded to a side peripheral surface by being fitted into a fitting hole of the resin outer peripheral material and heated by induction heating, and a side peripheral surface of the resin welding core metal The present invention relates to a composite member to which a resin outer peripheral material is welded, and a method for manufacturing the composite member.

  Conventionally, a composite member in which a resin outer peripheral material is welded to a side peripheral surface of a resin welding core is used for various parts. For example, it is also used for a worm wheel of an electric power steering device. In a worm wheel of an electric power steering apparatus or the like, it is required that the resin welding core metal and the resin outer peripheral member are securely joined in order to ensure operation reliability, durability, and the like.

  There has been proposed a technique for welding a resin outer peripheral material to a side peripheral surface of a resin welding core metal by fitting a resin welding core metal into a fitting hole of the resin outer peripheral material and performing induction heating. For example, in the method of fixing a metal boss to a resin molded product described in Patent Document 1 below, first, an unevenness process is performed on the resin contact surface of the metal molded body. A through hole having a diameter slightly smaller than the outer diameter of the metal molded body is formed in the resin molded product. A binder is applied to the uneven surface of the metal molded body, the resin molded product is heated to expand the diameter of the through holes, and the metal molded body is press-fit. Thereafter, the metal contact portion of the resin molded product is brought to the melting temperature or higher by high frequency induction heating, and the resin molded product is welded to the metal molded body. According to the method of Cited Document 1, a molded product such as a flat gear or wheel made of resin and metal can be efficiently manufactured.

  For example, in the method for manufacturing a worm wheel described in Patent Document 2 below, first, an outer periphery unevenness portion arranged in the circumferential direction is formed on the outer periphery of a metal core metal, and the outer periphery unevenness of the core metal is formed on the inner periphery of the resin ring gear. Inner circumferential irregularities arranged in the circumferential direction in a shape corresponding to the portion are formed. An adhesive is interposed between the ring gear and the core metal so that the outer peripheral uneven portion and the inner peripheral uneven portion are engaged, and then bonded by high frequency welding. In the method of the cited document 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 technology in which a resin welding core metal is fitted into a fitting hole of a resin outer peripheral material and induction heating is performed, in order to improve the bonding strength by welding between the resin outer peripheral material and the resin welding core metal, An uneven shape was formed on the side peripheral surface of the welding core. For example, in patent document 1, in order to improve joining strength, the knurling process of 1-3 mm was given. In Cited Document 2, male serrations are formed on the outer periphery of a metal core in order to improve the fixing force.

JP 2003-118006 A JP 2001-141033 A

However, in the conventional method, in order to improve the bonding strength of the resin outer peripheral material to the resin-welded core metal, the uneven shape has been formed larger.
However, in the case of increasing the uneven shape, in order to form the uneven shape on the metal core to be welded by knurling, a larger pressing force or machining is required at the time of processing. Moreover, when a large uneven shape is formed on the resin welding core, it is possible to fit by providing an uneven shape with a shape corresponding to the uneven shape on the inner peripheral surface of the resin outer peripheral material as in Cited Document 2. . For this reason, it takes time and effort to improve the bonding strength of the resin outer peripheral material to the resin welding core.

  Then, this invention made the 1st objective to provide the resin welding core metal which can improve joint strength with a resin outer periphery material easily, and joint strength was improved using such a resin welding core metal. A second object is to provide a composite member. It is a third object of the present invention to provide a method for manufacturing a composite member that can easily improve the bonding strength between a resin welding core metal and a resin outer peripheral material.

  Even if the resin outer peripheral material is fitted into the fitting hole of the resin welding core and induction heated, if the resin of the resin outer peripheral material does not sufficiently enter the uneven surface, the gap between the uneven surface and the resin outer material An unwelded portion such as a fine gap is generated. When an unwelded part occurs, the bonding strength between the resin welding core metal and the resin outer peripheral material is reduced by that amount, and the circumferential bonding strength and the central axis direction bonding strength of the resin outer peripheral material to the resin welding core metal are reduced. To do.

  When the uneven shape of the uneven surface is increased in order to increase the bonding strength between the resin welding core metal and the resin outer peripheral material, the interval between the contact between the resin welding core metal and the resin outer peripheral material in the fitted state before welding Are separated or the contact area is reduced. If induction heating is performed in this state, the inner peripheral surface of the resin outer peripheral material cannot be uniformly melted by the heat from the resin welding core, and the unmelted portion increases or is locally overheated and the resin is not melted. A uniform deformed portion or the like is generated. Even if the concave and convex shape is provided on the inner peripheral surface of the resin outer peripheral material, an unmelted portion or an overheated portion is generated at a portion where the concave and convex shape of the resin welding core does not match the concave and convex shape of the resin outer peripheral material.

  As a result, when the concave and convex shape is enlarged, if the resin outer peripheral material is welded to the core metal for welding by induction heating while preventing the overheated portion of the resin from occurring, the resin may enter every corner of the concave and convex portion. It was newly found that the bonding strength could not be sufficiently improved by generating an unwelded portion on the surface of the uneven portion.

Based on this knowledge, the resin welding core metal of the present invention that achieves the first object is fitted into the fitting hole of the resin outer peripheral material and induction heated so that the resin outer peripheral material is welded to the side peripheral surface. The resin welding cored bar is provided on the side peripheral surface with a plurality of streaky protrusions arranged adjacent to each other in the circumferential direction and on both end sides of the streaky protrusions. A plurality of streaky protrusions having a height of 1 mm or less, and a gap between adjacent streaky protrusions being 2 mm or less.

  According to such a resin welding core, since the gap between the adjacent linear protrusions is in a specific range, the entire joint surface of the resin outer peripheral material can be melted by the plurality of linear protrusions, and the unevenness The resin can fully penetrate into the part. Therefore, it is possible to easily improve the bonding strength with the resin outer peripheral material.

In the resin welding cored, streaky projection of several good that is provided to protrude at a height of less than 1mm outside the flat portion.
This resin welding core is made of a forged product having a concavo-convex part and a hollow part, and the hollow part may be provided so as to reach a position inside the bottom part of the concavo-convex part from the end face.

The composite member of the present invention that achieves the second object includes the above-described resin welding core and the resin outer peripheral material welded to the side peripheral surface of the resin welding core.
According to this composite member, since the above-described resin welding core is used, it is possible to improve the bonding strength between the resin welding core and the resin member.

The manufacturing method of the composite member of the present invention that achieves the third object is that the resin welding core is fitted into the fitting hole of the resin outer periphery and induction heating is performed on the side peripheral surface of the resin welding core. A method for manufacturing a composite member, in which a resin outer peripheral material is welded, a flat inner wall surface is provided in a fitting hole of the resin outer peripheral material, and a plurality of streaky protrusions are circumferentially provided on a side peripheral surface of the resin welding core Provided between the ridges adjacent to each other and the flat portions arranged on both ends of the ridge-like protrusions, the height of the plurality of ridge-like protrusions being 1 mm or less, and the gap between the adjacent stripe-like protrusions Is formed to be 2 mm or less, and the tops of the plurality of streaky protrusions are brought into contact with the flat inner wall surface by fitting the fitting holes of the resin outer peripheral material to the side peripheral surface of the resin welding core metal , and the flat portion is spaced to the inner wall surface of the resin outer peripheral member are opposed, producing composite member by welding the subsequent induction heating resin outer peripheral material in the resin welding core metal That.

  If a composite member is manufactured in this way, a flat inner wall surface is provided in the fitting hole of the resin outer peripheral material and brought into contact with a plurality of streaky protrusions, so that the streaky protrusions on the flat inner wall surface are in contact with each other. Can be reliably melted. Therefore, if the flat inner wall surface facing the concavo-convex part of the resin welding core is sufficiently melted and inserted into every corner between the line-shaped protrusions, the flat part of the resin welding core and the resin outer peripheral material The flat inner wall surface of the resin outer peripheral material can be welded to the side peripheral surface of the resin welding core metal with sufficient strength. In addition, a plurality of streak protrusions and flat portions are provided on the side peripheral surface of the resin welding core metal, and a flat inner wall surface that contacts the plurality of streaky protrusions is provided on the resin outer peripheral material. Therefore, the bonding strength of the composite member can be easily improved.

In this method for manufacturing a composite member, it is preferable to provide the flat portion so that the plurality of streak-like protrusions have a height of 1 mm or less from the flat portion .

  In this method of manufacturing a composite member, the core metal for welding may be formed by forging including a concavo-convex portion and a hollow portion reaching from the end surface to the inside of the bottom of the concavo-convex portion.

According to the resin welding core metal of the present invention, the height of the plurality of streaky protrusions formed on the side peripheral surface and the gaps between the adjacent streaky protrusions are within a specific range. It is possible to provide a core metal for welding with improved bonding strength with the outer peripheral material.
According to the composite member of the present invention, since the resin welding core is used, it is possible to provide a composite member having improved bonding strength between the resin welding core and the resin member.
According to the method for producing a composite member of the present invention, a plurality of streaky protrusions and flat portions are provided on the side peripheral surface of the resin welding core, and a flat inner wall surface is provided in the fitting hole of the resin outer peripheral member. Since it is made to fit and induction-heated, the manufacturing method of the composite member which can improve the joining strength of the resin welding core metal and the resin outer peripheral material easily can be provided.

(A) is the front view which shows the composite member which concerns on embodiment of this invention, and shows a part in cross section, (b) is a side view which shows a part of composite member in a cross section. (A) is a front view of the resin welding core metal which concerns on embodiment of this invention, (b) is a side view which shows a part of resin welding metal core in a cross section. It is the elements on larger scale which show the streaky process of the metal core for resin welding concerning the embodiment of the present invention. (A) is sectional drawing which shows the state before welding with the streaky processus | protrusion of the metal core for resin welding which concerns on embodiment of this invention, and the resin outer peripheral material, (b) is the streak process and resin of the metal core for resin welding. It is sectional drawing which shows the state after welding with a peripheral material. (A)-(e) is a figure explaining the manufacturing process of the composite member which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 5.
As shown in FIGS. 1A and 1B, the composite member 10 of this embodiment has a substantially disc shape centered on the central axis L, and includes a resin welding core 20 and a resin welding core 20. And a resin outer peripheral material 30 welded to the side peripheral surface 21. This composite member is an example of a worm wheel blank for electric power steering. The worm wheel blank is an intermediate body capable of manufacturing a worm wheel of an electric power steering device by forming a gear groove on the outer peripheral surface.

  As shown in FIGS. 2A and 2B and FIG. 3, the resin welding cored bar 20 of the composite member 10 has a substantially disc shape with a predetermined length in the direction of the central axis L, and the central axis L at the center. A through-hole 22 formed in a constant cross-sectional shape is provided. One end surface is formed flat, and the other end surface is formed with an annular groove-shaped hollow portion 23. The side circumferential surface 21 is formed in parallel along the central axis L, and has a concavo-convex portion 24 provided in an annular shape over the entire length in the circumferential direction, and circular in cross section at both ends in the direction along the central axis L of the concavo-convex portion. And a formed flat portion 25.

The concavo-convex portion 24 is configured by arranging a large number of streak-like projections 26 adjacent to each other in the circumferential direction. A large number of the streaky protrusions 26 are preferably arranged uniformly at a constant pitch over the entire circumference.
The shape of each line-like protrusion 26 is preferably a shape that easily melts the resin in contact with the inner surface of the fitting hole 31 of the resin outer peripheral material 30 during induction heating described later, and after welding It is preferable to make the shape easy to secure the bonding strength between the side peripheral surface of the resin welding core metal and the resin member. Therefore, the shape of many streak-like protrusions 26 should be the same, and preferably all the streak-like protrusions 26 have the same shape.

  In this embodiment, all the streaky protrusions 26 are formed in the same shape. As shown in FIG. 3, each of the streaky protrusions 26 has a mountain shape or a substantially triangular shape in which the top portion 26 a is narrow and the bottom portion 26 b is widened in the circumferential cross-sectional shape. Both side surfaces may be formed on either a flat surface or a curved surface. If it is such a shape, at the time of the induction heating mentioned later, it will be easy for molten resin to enter into the gap | interval 27 between the adjacent linear protrusions.

The top part 26a does not need to be a curved surface or a flat surface, and may have a pointed shape.
It is preferable that the shape of the bottom part 26b between the adjacent linear protrusions 26 is a plane or a curved surface. With such a bottom portion 26b, the molten resin can be sufficiently filled in the bottom portion 26b during induction heating.

  Both side surfaces of each streaky protrusion 26 may be symmetric or asymmetric with respect to the top 26a. Although the gradient of each side surface is not particularly limited, the maximum angle θ of each side surface with respect to the normal line of the side peripheral surface 21 of the resin welding core 20 is, for example, 30 degrees to 60 degrees, preferably 40 degrees to 50 degrees. Degree. When the maximum angle θ is excessively small, the gap 27 between the adjacent linear protrusions 26 becomes deep, so that the molten resin does not easily enter the gap 27 during induction heating described later. On the other hand, if the maximum angle θ is excessively large, the gap 27 between the adjacent linear protrusions 26 becomes shallow, so that a mechanical locking force in the circumferential direction between the linear protrusions 26 and the resin outer peripheral member 30 is obtained. It becomes difficult.

Each streak 26 may be parallel to the central axis L or may be inclined with respect to the central axis L. If each streaky protrusion 26 has a shape parallel to the central axis L, the resin-welded core 20 can be produced by forging.
Further, the shape of each of the streaky protrusions 26 in the direction along the central axis L may be changed in the longitudinal direction. However, if it has a constant cross-sectional shape or a convex shape over the entire length, the resin welding core 20 is formed by forging. Is easy to produce.

  The height H of each line-like protrusion 26 is preferably 1 mm or less. The height H of the line-like protrusions 26 is the difference between the distance from the central axis L to the top part 26a of each line-like protrusion 26 and the distance from the central axis L to the bottom part 26b between the adjacent line-like protrusions 26. It is. If the height H of each linear protrusion 26 is excessively high, the depth of the gap 27 between the adjacent linear protrusions 26 becomes too deep, and the molten resin does not sufficiently enter. On the other hand, the height H of each streaky protrusion 26 is preferably 0.5 mm or more, particularly preferably 0.7 mm or more. If the height H of each linear protrusion 26 is excessively low, a mechanical locking force in the circumferential direction between the resin welding core 20 and the resin outer peripheral material and the direction along the central axis L is secured after welding. It becomes difficult to do.

  In the concavo-convex portion 24, the gap 27 between the adjacent linear protrusions 26 is preferably 2 mm or less, that is, the maximum interval D of the gap 27 is preferably 2 mm or less. The maximum distance D of the gap 27 between the adjacent linear protrusions 26 is a distance along the circumferential direction between the apexes 26a of the adjacent linear protrusions 26. For example, in the case where the top 26a of each streaky protrusion 26 has a pointed shape, the distance between the tops 26a of the streaky protrusions 26 may be approximated by a straight line, and the top 26a of each streaky protrusion 26 may be flat or curved on the top 26a. If corners are provided on both sides, the distance between the corners may be approximated by a straight line. In addition, when the top part 26a of each linear protrusion 26 is a curved surface shape and the corner | angular part is not provided, it is good also as the distance approximated by the straight line between the parts which the resin outer peripheral material 30 mentioned later contacts actually.

If the gap 27 between the adjacent linear protrusions 26 is excessively wide, the adjacent linear protrusions are heated by the heat supplied from the respective linear protrusions 26 to the resin outer peripheral material 30 during induction heating described later. The resin between the resin outer peripheral materials 30 with which the top portions 26a of the 26 come into contact cannot be sufficiently melted, and an unwelded portion is likely to occur.
If the gap 27 between the adjacent line-like protrusions 26 is excessively narrow, the depth of each line-like protrusion 26 cannot be increased, so that the shape of the protrusion amount becomes small. It becomes difficult to ensure sufficient joint strength between the two. The maximum distance D of the gap 27 between the adjacent linear protrusions 26 is preferably 1 mm or more.

  The flat portion 25 of the resin welding core metal 20 is provided at a position adjacent to the uneven portion 24 in the direction along the central axis L, that is, a position adjacent to both end sides of the numerous streaky protrusions 26. The flat portion 25 is formed of a surface parallel to the central axis L having no irregularities, and is preferably formed of a curved surface having a circular cross section. The flat portion 25 is formed so that at least the distance from the central axis L is smaller than the top portion 26a of the line-like protrusion 26 of the uneven portion 24. By providing the flat portion 25 at such a distance, the tops of the many line-like protrusions 26 have a height of 1 mm or less outside the flat portion 25. This height is preferably 0.5 mm or more, particularly preferably 0.7 mm or more. Therefore, if the flat inner wall surface 32 (described later) of the resin outer peripheral member 30 is heated while facing the resin outer peripheral member 30, the resin outer peripheral member 30 can be welded to the flat portion 25 by the heat supplied from the large number of streaky protrusions 26.

  The distance from the central axis L of the flat portion 25 is preferably equal to or less than the distance between the bottom portion 26b between the adjacent linear protrusions 26 and the central axis L, and from the central axis L of the flat portion 25. It is particularly preferable that the distance is formed at the same distance as the bottom part 26b between the streaky protrusions 26 adjacent to each other. By welding the resin outer peripheral member 30 to the flat portion 25 after welding, a mechanical locking force in the direction along the central axis L is obtained between both ends of each linear protrusion 26 and the resin outer peripheral member 30. Bonding strength can be improved.

The width W in the direction along the central axis L of the flat portion 25 is preferably formed to be not less than 0.5 times the maximum distance D in the gap 27 between the streak protrusions 26 adjacent to each other. At the time of induction heating described later, the resin outer peripheral material 30 facing the flat portion 25 is softened or melted by the heat of each of the streaky protrusions 26. When the resin outer peripheral material 30 disposed between the adjacent linear protrusions 26 is heated to such an extent that the resin outer peripheral material 30 is sufficiently melted, the portions adjacent to the ends of the individual linear protrusions 26 are also melted to the same extent. become. Therefore, if the width of the flat portion 25 is formed to be 0.5 times or more of the maximum distance D in the gap 27 between the adjacent streaky projections 26, the portion adjacent to the end of each streaky projection 26 When they are sufficiently softened or melted, it is possible to ensure an area in which they can be welded. Therefore, the flat part 25 and the resin outer peripheral material 30 can be welded with sufficient width on both end sides of the large number of streaky protrusions 26, and the central axis L between the resin welding core metal 20 and the resin outer peripheral material 30. It is possible to ensure a mechanical locking force in a direction along the direction.
For example, the width W of the flat portion 25 may be equal to or less than the maximum interval D of the gap 27. If the width W of the flat portion 25 is excessively wide, an incomplete welded portion may be formed between the flat portion 25 and the resin outer peripheral material 30.

The hollow portion 23 and the through hole 22 of the resin welding core 20 are formed as necessary, and the shape and size thereof are arbitrary. In this embodiment, the hollow portion 23 is formed in a groove shape opened on one end face of the resin welding core 20 and has a depth that reaches the inside of the bottom portion 26 b of the uneven portion 24. Therefore, the thickness between the hollow part 23 and the bottom part 26b of the uneven part 24 is thin. If the thickness of this part is thin, the heat capacity can be reduced, so that the temperature can be easily raised during heating.
The hollow part 23 may be a groove provided on each end face of the resin welding core 20, and is locally provided on one or both end faces at a depth that reaches the position inside the uneven part 24. It may be a hole. Furthermore, the hole provided locally so that it might penetrate between the both end surfaces of the resin welding core metal 20 may be sufficient.

  Such a metal core 20 for welding a resin can ensure various desired properties such as strength necessary for the use of the obtained composite member, that is, in the case of this embodiment, the use of a worm wheel. And so on. It is preferable that the resin welding core metal 20 is formed in an integrated shape provided with the concave and convex portions 24 and the flat portions 25 by providing the through holes 22 and the hollow portions 23 by forging.

  If it is forging, since the through-hole 22, the hollow part 23, etc. can be provided without removing material, waste of material can be omitted. For forging, unlike knurling, the shape, height H, maximum distance D of gap 27, position, size, etc. can be freely set and adjusted. Thus, the optimum bonding strength of the resin outer peripheral material 30 can be ensured. In addition, if a plurality of streaky protrusions 26 are formed by forging, it is not necessary to press the side peripheral surface from the outside to form the uneven portions 24 as in knurling, and the hollow portions 23 and the bottom portions 26b of the uneven portions 24 are not required. The streak-like protrusions 26 can be easily formed on the side peripheral surface 21 even when the thickness between the two is as thin as the present embodiment, for example, 5 mm or less.

  On the other hand, the resin outer peripheral member 30 is a resin member welded to the side peripheral surface 21 of the resin welding core 20. The resin outer peripheral member 30 is made of a thermoplastic resin that can be melted or softened by heat when the resin welding core 20 is heated while being in contact with the resin welding core. It can be selected according to the use of the member. When the fitting hole 31 side is heated to the melting temperature or higher, it is preferable to use a heat conductive material that does not melt the surface side.

  In this embodiment, polyamides such as 6,6-nylon, 6-nylon, and 4,6-nylon are used in order to ensure the strength required for the worm wheel and to make it easy to ensure heat resistance. In particular, 6-nylon is preferable because it is easy to ensure the strength, and MC nylon (registered trademark, manufactured by Nippon Polypenco Co., Ltd.) having excellent mechanical strength, thermal characteristics, and chemical properties is particularly preferable. . In order to ensure slidability, 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 peripheral surface of the resin outer peripheral member 30 is in close contact with the side peripheral surface 21 of the resin welding core 20 and is provided on the side peripheral surface 21 of the resin welding core 20 as shown in FIG. A large number of the streaky protrusions 26 are completely buried, and enter the gaps 27 between the streaky protrusions 26 and are sufficiently welded to the streaky protrusions 26. Moreover, it welds enough to the flat part 25 provided in the both ends of the side peripheral surface 21 of the resin welding core metal 20. As shown in FIG.
Thus, in the state where the resin outer peripheral material 30 is welded to the core metal 20 for resin welding, since many streak-like protrusions 26 are completely embedded, the resin welding that is visually recognized from both end surface sides of the composite member 10. As shown in FIG. 1, the boundary line between the core metal 20 for use and the resin outer peripheral member 30 has a circular shape formed by the end of the flat portion 25.
In addition, the outer periphery shape and thickness of the resin outer peripheral material 30 are the dimension including the machining allowances, such as a gear tooth of a worm wheel.

Next, a method for manufacturing the composite member 10 will be described.
In order to manufacture the composite member 10, a preparation step of preparing the resin outer peripheral material 30 and the resin welding core metal 20, and a fitting hole 31 of the resin outer peripheral material 30 on the side peripheral surface 21 of the resin welding core metal 20. A fitting step for fitting and producing the combination member 40 and a welding step for welding the resin outer peripheral material 30 fitted to the side peripheral surface of the resin welding core 20 by induction heating the resin welding core 20. And a pre-processing step for realizing accuracy as the composite member 10.

First, in a preparation process, as shown to Fig.5 (a) (b), the resin welding core metal 20 and the resin outer peripheral material 30 are each formed separately.
As shown in FIG. 5 (b), the resin welding cored bar 20 has a concavo-convex part 24 in which a plurality of streaky protrusions 26 are arranged adjacent to each other in the circumferential direction on the side peripheral surface 21 of the resin welding cored bar 20. The flat portions 25 formed on both end sides of the plurality of streaky protrusions 26 are provided by forging. At this time, the width W along the central axis L of the flat portion 25 is formed to be larger than 0.5 times the maximum interval D in the gap 27 between the adjacent linear protrusions 26.
After forging, it is possible to perform machining or the like as necessary. In machining, each part is formed with a predetermined accuracy, or both end faces are made orthogonal to the central axis L with a predetermined accuracy.

  As shown in FIG. 5A, the resin outer peripheral material 30 is formed in a ring shape by molding a thermoplastic resin or the like. In this embodiment, the resin outer peripheral member 30 includes an outer peripheral surface 33 having a circular cross section parallel to the central axis L, and a fitting hole 31 having an inner wall surface corresponding to the side peripheral surface 21 of the resin welding core metal 20. And both end faces made of a plane. The thickness between both end surfaces corresponds to the length in the direction along the central axis L of the concavo-convex portion 24 provided on the side peripheral surface 21 of the resin welding core 20 and the flat portions 25 on both sides thereof.

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

  The fitting hole 31 should have a shape in which the tops of as many streaky projections as possible, preferably the tops of all the streaky projections are in contact, and the inner diameter of the flat inner wall surface 32 of the fitting hole 31 is made of resin. It is preferable that the dimensions are such that the concave and convex portions 24 of the welding core 20 can be fitted. Specifically, the inner diameter of the flat inner wall surface 32 is set slightly smaller than the maximum diameter formed by the top portion 26 a of the uneven portion 24, for example, the inner diameter of the flat inner wall surface 32 is smaller than the maximum diameter of the uneven portion 24. And 0.4 to 3% smaller. If the inner diameter of the flat inner wall surface 32 is excessively large with respect to the maximum diameter of the concavo-convex portion 24, the flat inner wall surface 32 cannot be sufficiently heated by the heat of a large number of streaky protrusions 26 during induction heating described later, In some cases, it is difficult for the molten resin to sufficiently enter the gap 27 between the streaky protrusions 26 adjacent to each other. On the other hand, when the inner diameter of the flat inner wall surface 32 is excessively small with respect to the maximum diameter of the concavo-convex portion 24, the resin outer peripheral material 30 itself is deformed.

Next, in the fitting step, as shown in FIG. 5C, the fitting hole 31 of the resin outer peripheral material 30 is fitted to the side peripheral surface 21 of the resin welding core metal 20, so that FIG. As shown, the flat inner wall 32 is brought into contact with the tops of the plurality of streak-like protrusions 26 and the flat portion 25 is opposed to the flat inner wall surface 32.
In order to fit the resin welding core metal 20, for example, the resin outer peripheral material 30 may be heated and expanded to be fitted to the side peripheral surface 21 of the resin welding core metal 20. For example, the resin outer peripheral material 30 is heated in a heating furnace or the like, and the diameter of the fitting hole 31 is expanded so as to become a diameter corresponding to the outer diameter of the resin welding core metal 20. The welding core 20 can be easily inserted.
The heating temperature can be set by the inner diameter of the fitting hole 31 with respect to the outer diameter of the resin welding core 20, the type of thermoplastic resin, the softening point, the expansion coefficient, and the like. For example, in the case of polyamide, the temperature is preferably about 130 to 150 ° C. If the heating temperature is excessively high, the accuracy of the resin outer peripheral member 30 may be lowered. If the heating temperature is excessively low, it takes time to insert the resin outer peripheral member 30.

The fitting between the side peripheral surface 21 of the resin welding core 20 and the fitting hole 31 of the resin outer peripheral member 30 is performed in the axial direction with a press machine or the like while performing parallelism and alignment using a jig or the like, for example. Can be inserted under pressure. Thus, the combination member 40 which combined the metal core 20 for resin welding and the resin outer peripheral material 30 is produced.
Prior to this fitting step, the side peripheral surface 21 of the resin welding core 20 and the resin outer periphery 30 are fitted to improve the bonding strength between the resin welding core 20 and the resin outer periphery 30. One or both of the joint holes 31 may be provided with a bonding strength improver layer such as various adhesives.

  Next, in the welding step, as shown in FIG. 5 (d), the resin outer peripheral material 30 is welded to the concavo-convex portion 24 and the flat portion 25 of the resin welding core 20 by induction heating. Although this welding process is performed using an apparatus capable of raising the temperature of the resin welding core 20, a high frequency induction heating apparatus is used in this embodiment. In this apparatus, a heating coil 50 that generates an alternating magnetic field is provided, and by controlling power feeding to the heating coil 50, the side peripheral surface of the resin welding core metal 20 can be adjusted to a desired temperature. Further, during heating, the combination member 40 and the heating coil 50 can be rotated relative to each other about the central axis L.

  During heating, a high frequency current is passed through the heating coil 50 to inductively heat the resin welding core 20, and the surface temperature of the resin welding core 20 is maintained in a temperature range equal to or higher than the melting temperature of the resin constituting the resin outer periphery 30. To do.

  As a result, the portion of the resin outer peripheral member 30 that is in contact with the streaky protrusions 26 on the side peripheral surface 21 and the adjacent portion thereof are heated by the heat of the resin welding core 20 to be softened or melted. As a result, the resin between the streaky protrusions 26 adjacent to each other melts, enters the gap 27 between the streaky protrusions 26, and the molten resin comes into close contact with the uneven portion 24. Also, the softened or melted resin in the vicinity of the resin outer peripheral material 30 adjacent to a large number of the streaky protrusions 26 is in close contact with the periphery of the flat portion 25 of the resin welding core 20.

  In this melting step, it is also possible to support a plurality of combination members 40 on a shaft-like jig and collectively heat them by induction heating. As the shaft-shaped jig, for example, a tool that is fixed by penetrating through the through-hole 22 of each resin welding core 20 and can be moved relative to the heating coil 50 in this state can be used.

  After the welding step, for example, the resin is solidified in a state where the molten resin is in close contact with the side peripheral surface of the resin welding core 20 by radiating heat in the atmosphere or cooling with a coolant.

In this embodiment, a pre-processing process is implemented after that. In the pre-processing step, the end surface of the resin outer peripheral material 30 and the end surface of the resin welding core 20 are machined to form, for example, a planar shape. Here, the width W along the central axis L of the flat portion 25 is narrowed by cutting the end face as shown in FIG. The amount of cutting the end face can be adjusted as appropriate. For example, it is set to be equal to or less than the maximum distance D in the gap 27 between the adjacent linear protrusions 26. As a result, a portion where the flat portion 25 of the resin welding core 20 and the resin outer peripheral material 30 are incompletely welded is removed, and the flat portion 25 and the resin outer peripheral material 30 are completely welded to both ends over the entire circumference. It can be in the state that was made. The width W of the flat portion 25 may be 0.5 times or more and 1 time or less of the maximum distance D of the gap 27 by processing. If the width W of the flat portion 25 is excessively narrowed, the locking force in the direction along the central axis L between the resin welding core metal 20 and the resin outer peripheral material 30 may be reduced.
In this pre-processing step, for example, the accuracy of each part such as the accuracy 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, and the orthogonality of both end surfaces is preferably processed within a predetermined range.
This completes the production of the composite member 10 as shown in FIG.

  When the keyway is formed in the through hole 22 and the desired tooth portion or the like is accurately processed on the outer periphery of the resin outer peripheral material 30 with respect to the composite member 10 thus obtained, the worm wheel which is the final product can be obtained. Can be manufactured.

  When the composite member 10 is manufactured as described above, the height H of the plurality of streak protrusions 26 and the gaps 27 between the streak protrusions 26 adjacent to each other are specified in the resin welding core 20 used. is doing. As a result, when the side peripheral surface 21 of the resin welding core 20 is fitted into the fitting hole 31 of the resin outer peripheral member 30 and induction heating is performed, the resin outer peripheral member 30 that contacts each of the heated streaky protrusions 26 is obtained. When melted, the molten resin can surely enter into the gaps 27 between the streaky protrusions 26 to every corner. Therefore, an unwelded portion is prevented from being generated, and the resin outer peripheral material 30 can be reliably welded to the side peripheral surface 21 of the resin welding core 20.

  Moreover, if the fitting hole 31 of the resin outer peripheral material 30 is fitted to the side peripheral surface 21 of the resin welding core 20 and induction heating is performed, the heated streaky protrusions 26 are adjacent to the concavo-convex portion 24. The resin outer peripheral material 30 at the position and the resin outer peripheral material 30 at the positions on both ends adjacent to the concavo-convex portion 24 are melted. Therefore, the molten resin enters the gap 27 between the streaky protrusions 26, the streaky protrusions 26 and the resin outer peripheral material 30 are welded, and melted at adjacent positions on both ends of each streaky protrusion 26. The resin reaches the flat portion 25 and the flat portion 25 and the resin outer peripheral material 30 are welded. As a result, the entire concavo-convex portion 24 is embedded in the resin outer peripheral material 30.

  As a result, after the resin outer peripheral material 30 is welded, the concave and convex portions 24 are not visually recognized from both end surfaces of the resin welding core 20 and an excellent appearance is obtained. Further, by welding the plurality of streaky protrusions 26 and the resin outer peripheral member 30, in addition to the bonding strength by welding, the resin that has entered between the side surfaces of the plurality of streaky protrusions 26 and each of the streaky protrusions 26, and A mechanical locking force in the circumferential direction is obtained between the two ends, and a mechanical locking force in the direction along the central axis L between both ends of the plurality of streaky protrusions 26 and the resin on the flat portion 25. Is obtained. Therefore, it is possible to weld the resin outer peripheral material 30 to the resin welding core 20 with sufficient strength.

  Moreover, in the resin-welded core 20, the width W of the flat portion 25 is 0.5 times or more the maximum distance D in the gap 27 between the adjacent linear protrusions 26. When the resin outer peripheral material 30 disposed between the adjacent linear protrusions 26 is sufficiently melted by the heat of the respective linear protrusions 26 during welding, the linear protrusions 26 of the resin outer peripheral material 30 are heated. The vicinity of the part in contact with is also melted. Therefore, the resin sufficiently melted adjacent to the streaky protrusion 26 of the resin outer peripheral member 30 can be reliably bonded to the flat portion 25 of the resin welding core 20, thereby Sufficient bonding strength with the resin outer peripheral 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 distance D in the gap 27 between the adjacent linear protrusions 26, and the side peripheral surface of the resin welding core 20 After the resin outer peripheral material 30 is welded to 21, the end face is cut so as to narrow the width of the flat portion 25 of the core metal 20 for resin welding.

  Therefore, the portion where the flat portion 25 is wide at the time of welding and the resin outer peripheral material 30 is sufficiently melted at both end sides can be reliably welded to the flat portion 25. And since the end surface of the resin welding core metal 20 is cut after welding, the composite member 10 in which the resin outer peripheral material 30 and the resin welding core metal 20 are sufficiently welded to the end portion is obtained.

  Therefore, in such a manufacturing process, it is not necessary to largely form the uneven shape of the uneven portion 24 of the resin welding core metal 20, and it is not necessary to provide the uneven shape on the inner surface of the resin outer peripheral material 30. Therefore, the joint strength between the resin welding core 20 and the resin outer peripheral member 30 can be easily improved.

Hereinafter, examples and comparative examples will be described.
(Example)
A resin-welded core 20 as shown in FIG. 2 is produced, and a ring-shaped resin outer peripheral material 30 corresponding to this is fitted to the side peripheral surface of the resin-welded core 20 and welded by high-frequency induction heating. Thus, the composite member of the example was manufactured.
The resin welding core 20 is made of carbon steel and has a maximum diameter of 60 mm and a thickness of 16 mm. The side peripheral surface 21 is provided with flat portions 25 of 2 mm on both ends, and a plurality of streak-like protrusions 26 are provided between them. They are arranged adjacent to each other in the direction. The cross-sectional shape in the circumferential direction of each streak-like protrusion 26 has a substantially triangular shape, and the angle of the apex 26a is approximately 90 degrees symmetrical with respect to the normal from the central axis L. The height of each line-like protrusion 26 was 0.9 mm, and the maximum distance D in the gap between the adjacent line-like protrusions 26 was 1.9 mm. On the other hand, the resin outer peripheral material 30 is a resin molded body made of MC nylon (manufactured by Nippon Polypenco, 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.
In the induction heating, the power supply to the coil was controlled and heated so that the surface temperature of the core metal 20 for resin welding became approximately the 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 at the position of the bottom 26b between the adjacent linear protrusions 26 was observed. In the example, the bottom 26b between the adjacent linear protrusions 26 was observed. It was confirmed that the resin outer peripheral material 30 was sufficiently present in the entire position and was welded to the bottom 26b.

  Next, six composite members 10 are produced in the same manner as described above, and a load is applied so as to be in opposite directions along the central axis L with respect to the resin welding core metal 20 and the resin outer peripheral material 30. The 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)
Except that the height of each line-shaped protrusion of the resin-welded core metal is larger than 1 mm and the maximum distance D in the gap 27 between the adjacent line-shaped protrusions 26 is larger than 2 mm, all are the same as in the embodiment. Thus, a composite member was produced.
When the obtained composite member 10 was cut in the central axis direction and a cross section at the position of the bottom portion 26b between the adjacent linear protrusions 26 was observed, in Comparative Example 1, between the adjacent linear protrusions 26, There were many fine unwelded locations on the bottom 26b side.
Moreover, six composite members 10 were produced, a load was applied to the resin welding core metal 20 and the resin outer peripheral material 30 in the opposite directions 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 compared to the examples.

DESCRIPTION OF SYMBOLS 10 Composite member 20 Resin welding core 21 Side peripheral surface 22 Through-hole 23 Hollow part 24 Uneven part 25 Flat part 26 Streaky protrusion 26a Top part 26b Bottom part 27 Gap 30 Resin outer peripheral material 31 Fitting hole 32 Flat inner wall surface 33 Outer part Surface 40 Combination member 50 Heating coil L Center axis H Height W Width

Claims (7)

It is a manufacturing method of a composite member, wherein the resin outer peripheral material is welded to the side peripheral surface of the resin welding core by fitting and heating the resin welding core to the fitting hole of the resin outer peripheral material,
Provide a flat inner wall surface in the fitting hole of the resin outer peripheral material,
Provided on the side peripheral surface of the resin welding core metal are a concavo-convex portion in which a plurality of streak-like projections are arranged adjacent to each other in the circumferential direction, and a flat portion arranged on both ends of the streaky projections. The height of the line-shaped protrusions is 1 mm or less, and the gap between the line-shaped protrusions adjacent to each other is formed to be 2 mm or less.
By fitting a fitting hole of the resin outer peripheral material into a side peripheral surface of the resin welding core metal, the top portions of the plurality of streaky protrusions are brought into contact with the flat inner wall surface, and the flat portion is replaced with the resin. It is spaced apart and opposed to the inner wall surface of the outer peripheral material,
A method for producing a composite member, wherein the resin peripheral material is welded to the core metal for welding the resin by induction heating. The manufacturing method of the composite member according to claim 1 , wherein the flat portion is provided so that the plurality of streaky protrusions have a height of 1 mm or less from the flat portion.   3. The method for manufacturing a composite member according to claim 1, wherein the resin welding core is provided by forging including the uneven portion and a hollow portion reaching from the end surface to a position inside the bottom portion of the uneven portion. A resin welding core bar in which the resin outer peripheral material is welded to the side peripheral surface by being fitted into the fitting hole of the resin outer peripheral material and induction heating,
The aforementioned side peripheral surface includes a concave-convex portion formed by a plurality of stripe-like protrusions are arranged adjacent to each other in the circumferential direction, and a flat portion arranged respectively on both end sides of the streak protrusion, the ,
The core metal for welding a resin, wherein a height of the plurality of streaky protrusions is 1 mm or less, and a gap between the streaky protrusions adjacent to each other is 2 mm or less. The resin welding cored bar according to claim 4 , wherein the plurality of streaky protrusions are provided to protrude outward from the flat part at a height of 1 mm or less. The resin welding according to claim 4 or 5 , comprising a forged product having the uneven portion and a hollow portion, the hollow portion being provided so as to reach a position inside the bottom portion of the uneven portion from the end face. Core metal. A composite member comprising the core metal for welding a resin according to any one of claims 4 to 6 and a resin outer peripheral material welded to a side peripheral surface of the core metal for welding the resin.

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