JP4611237B2 - Internal tooth member and manufacturing method thereof - Google Patents

Description

  The present invention relates to an internal tooth member in which inner teeth are provided on an inner peripheral wall, and the inner teeth are carburized, and a method for manufacturing the same.

  A carburizing treatment in which carbon is diffused in a surface layer portion and a hardened layer is provided on the surface layer portion when a quenching treatment is performed on a metal member has been widely adopted. For example, the spider 1 shown in FIG. 11 is a member constituting a tripod type constant velocity joint, and carburizing treatment is performed on the inner teeth 3 formed on the inner peripheral wall of the through hole 2.

  When carburizing the spider 1 of this type, it is necessary to avoid forming an excessive hard layer on the inner teeth 3. In this case, since the hardness of the inner teeth 3 is increased more than necessary, the toughness is lowered and cracks are likely to occur.

  From such a viewpoint, conventionally, carburizing prevention treatment such as applying a carburizing inhibitor to the inner teeth 3 (see Patent Document 1) or providing nickel plating (see Patent Document 2) has been performed. Proposed. Further, as described in Patent Documents 3 and 4, it is also conceived that the inner teeth 3 are surrounded by a seal or a spacer in order to control the degree of formation of the hardened layer.

  However, when the carburizing inhibitor is used, it is necessary to perform a complicated operation of peeling and removing the carburizing inhibitor from the spider 1 after performing the carburizing process. In addition, there is an inconvenience that the depth of the hardened layer cannot be adjusted.

  On the other hand, when a seal or a spacer is used, the operator must manually install the seal or spacer, which takes a long time, resulting in a reduction in production efficiency.

  In order to avoid the above-mentioned problems, as proposed by the present applicant in Japanese Patent Application Laid-Open No. H10-293400, an inner member for a constant velocity joint is proposed as an example, a support shaft member made up of a pipe or the like standing on a frame is used as a plurality of spiders 1. Are sequentially laminated through the through-holes 2 and the carburizing gas is introduced into the gap while maintaining an annular gap formed between the inner teeth 3 of the spider 1 and the outer peripheral wall of the support shaft member at a constant distance. It is recalled to supply. In this case, the depth of the hardened layer formed on the inner teeth 3 of the spider 1 is substantially uniform, and the depth of the hardened layer is smaller than that of the hardened layer formed on the outer peripheral wall.

JP-A-2-298249 JP-A-6-2102 JP-A-4-263060 JP-A-60-103123 JP-A-9-324257

  When the technique described in Patent Document 5 is adopted, the end surfaces of the spiders are closely stacked. Therefore, the carburizing agent (gas) hardly leaks between adjacent spiders. For this reason, the carburizing agent is exposed only in two places, the lower end surface of the lowermost spider located directly above the frame body and the upper end surface of the spider stacked on the uppermost part, exposed in the stacked spiders. To do. Therefore, when it is desired to carburize each end face of the spider, it is not easy to cope with it.

  In the lowermost and uppermost spiders described above, a hardened layer is formed only on one end surface. Due to this, as shown in FIG. 12, a relatively large quenching distortion difference may occur in the lowermost and uppermost spiders, and when such a situation occurs, the dimensional accuracy of the spiders and by extension, the internal teeth. It becomes difficult to maintain. In particular, when the spider is a high-strength steel whose grain boundaries are strengthened by element addition, for example, boron steel, it has a large structural sensitivity compared to general case-hardened steel such as SCM steel, so it is hardened greatly. A difference in distortion occurs (see FIG. 12). Note that the numerical values shown in FIG. 12 are the results when the number of stacked layers is five. Represents the bottom, and 2 and 4 are respectively interposed between 1 and 3, and 3 and 5. The quenching strain difference was measured between the same parts of each spider. This is the dimensional difference before and after quenching.)

  The present invention has been made in order to solve the above-mentioned problem, and the internal teeth that are carburized on the internal teeth and both end faces and can therefore avoid the occurrence of quenching distortion differences as much as possible. It aims at providing a member and its manufacturing method.

In order to achieve the above object, the present invention is an internal tooth member having a ring portion provided with a through hole and having internal teeth formed on an inner peripheral wall of the through hole,
A passage extending from the through hole to the outer peripheral wall is provided on at least one of the both end faces of the ring portion where the through hole opens.
At least the inner teeth and the passage are carburized.

  That is, the internal teeth member is carburized over substantially the entire surface, and a hardened layer is provided for this purpose. Therefore, the occurrence of a quenching distortion difference is suppressed, and eventually dimensional accuracy is ensured. Thereby, the manufacturing yield of the internal toothed member is also improved.

  Here, the spider of a constant velocity joint can be mentioned as a suitable example of the internal tooth member.

  And as a suitable example of the material of the internal tooth member, boron steel can be mentioned. That is, the internal tooth member according to the present invention may be made of a material that makes it difficult to ensure dimensional accuracy because a relatively large quenching distortion difference occurs.

In addition, the present invention provides an internal member having a ring portion provided with a through hole and carburizing a molded body in which internal teeth are formed on the inner peripheral wall of the through hole to form an internal tooth member. A method for manufacturing a tooth member, comprising:
As the molded body, a step of providing a passage extending from the through hole to the outer peripheral wall on at least one end face of the ring portion where the through hole opens, and
A step of laminating the molded bodies by passing the through-holes of a plurality of the molded bodies through a shaft member standing on a base so that end surfaces provided with the passages face the same direction;
The laminated compact is heated in a heat treatment furnace, a carburizing agent is supplied into the heat treatment furnace, and the carburizing agent is passed through the passage or the through hole of the compact, and the carburizing agent is passed through the through hole or the passage. The process of discharging from the
Have
Carburizing treatment is performed on at least the inner teeth and the passage with a carburizing agent that has reached the passage or the through hole.

  In this way, a passage is provided in the internal toothed member, and gas or liquid can flow from the inner peripheral wall (internal tooth) side to the outer peripheral wall side or from the outer peripheral wall side to the internal tooth side. By doing so, it becomes possible to perform carburizing treatment on both end faces of the internal toothed member, and to provide a hardened layer. Since it can avoid that a quenching distortion difference arises by this, an internal gear member with favorable dimensional accuracy can be obtained.

  In addition, after the carburizing process is completed, the plurality of molded bodies are immersed in a cooling medium in a stacked state, and the cooling medium is circulated to the passage or the through hole through the through hole or the passage. It is preferable to do so. Thereby, a quenching process can be performed at once to the area | region where the carburizing process in the some said molded object was performed. That is, the efficiency of the quenching process is improved.

  As a preferable example of the internal teeth member, as described above, a constant velocity joint spider can be exemplified.

  Here, when the molded bodies are laminated, the upper opening portion of the passage is closed by the lower end surface of another molded body positioned immediately above the molded body. Usually, since the carburizing agent flows through the passage in this state, carburizing treatment is also applied to a part of the lower end surface of the molded body.

  According to the present invention, by providing a passage, gas or liquid can flow from the inner peripheral wall side of the internal toothed member to the outer peripheral wall side or in the opposite direction. During carburizing, gas flows from the inner teeth (inner peripheral wall) to the outside via the passage, or from the outside to the inner teeth via the passage, so that the wall surface of this passage and the position directly below or above the passage Carburizing treatment is performed on the end face of another molded body. Moreover, since the carburizing gas contacts the exposed outer peripheral wall and inner teeth of the inner tooth member, an inner tooth member that has been carburized over substantially the entire surface is obtained. Therefore, the occurrence of a quenching distortion difference is suppressed, and an internal gear member with excellent dimensional accuracy can be configured.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of an internal tooth member and a manufacturing method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an overall schematic perspective view of a spider (internally toothed member) 10 according to the present embodiment constituting a tripart type constant velocity joint. In this case, the spider 10 is made of boron steel, and a ring portion 14 having a through hole 12 provided along the axial direction at a substantially central portion thereof, and three trunnions 16a formed to protrude from the outer peripheral wall of the ring portion 14. ~ 16c.

  Internal teeth 18 are formed on the inner peripheral wall of the through hole 12. The teeth of a shaft member (not shown) are meshed with the internal teeth 18.

  The trunnions 16a to 16c are separated from each other at an interval of 120 °. Each of the trunnions 16a to 16c is fitted with a ring-shaped roller member via a plurality of rolling elements (both not shown). These roller members are inserted into sliding grooves provided on the inner peripheral wall of the outer member constituting the tripod type constant velocity joint. Accordingly, the shaft member is slidably connected to the tripod type constant velocity joint.

  Here, on the upper end surface of the spider 10 in FIG. 1, three passages 20a to 20c are provided so that a part of the upper end surface is cut out in an arc shape. Each of the passages 20a to 20c extends from the through hole 12 of the ring portion 14 to the outer peripheral wall. Therefore, each of the passages 20a to 20c functions as a gas or liquid flow passage from the through hole 12 to the outer peripheral wall, as will be described later.

  If the passages 20a to 20c are excessively deep, the strength of the spider 10 is reduced. On the other hand, if it is too shallow, it will not be easy for the carburizing gas and coolant described below to circulate. Accordingly, the depths of the passages 20a to 20c are set to such an extent that the spider 10 having a practically sufficient strength can be obtained and the carburizing gas and the coolant are reliably circulated.

  Similarly, the widths of the passages 20a to 20c are set to such an extent that the spider 10 exhibits a practically sufficient strength and the carburizing gas and the coolant are easily circulated.

  In the spider 10, at least the bottom wall surface and the side wall surface that form the passages 20 a to 20 c and the internal teeth 18 formed on the inner peripheral wall of the through hole 12 are subjected to carburizing treatment, so that a hardened layer is formed. Is formed. As will be described later, a hardened layer also exists on a part of the lower end surface.

  The spider 10 is formed from a workpiece made of boron steel by, for example, cold forging, and the like, after the preform 22 having a shape corresponding to the shape of the spider 10 is processed and formed, as shown in FIG. Using the mechanism 30, it can be manufactured as follows.

  The work holding mechanism (hereinafter simply referred to as a holding mechanism) 30 includes a plurality of frame bodies 32 arranged in parallel and a plurality of support shaft members (shafts) spaced apart by a predetermined distance along the longitudinal direction of the frame body 32. Member) 34. The support shaft member 34 is composed of a pipe in which a through hole 35 is formed along the axial direction, and is fixed between a pair of adjacent frame bodies 32 by, for example, welding.

  In this case, the support member 34 holds five preforms 22 as shown in FIGS. Then, the internal teeth 18 formed on the inner wall surface of the through hole 12 of each preform 22 and the side peripheral wall of the support shaft member 34 are separated from each other at a predetermined interval. In other words, a gap 36 is formed between the internal teeth 18 and the support shaft member 34.

  Here, the shape of the preformed body 22 is the same as that of the spider 10. Therefore, in the preformed body 22, the same components as those of the spider 10 are denoted by the same reference numerals, and detailed description thereof is omitted. Needless to say, the preform 22 has not been subjected to carburizing treatment, and therefore no hardened layer is formed.

  In the present embodiment, each of the preforms 22 is attached to the support shaft member 34 so that the end surfaces provided with the passages 20a to 20c face upward and the positions of the passages 20a to 20c are matched. Retained. That is, for example, the end face on the side where the passages 20a to 20c of the other preformed body 22 are not provided, that is, the lower end face is positioned immediately above the passages 20a to 20c of the preform 20. Thereby, the opening upper part of channel | paths 20a-20c is obstruct | occluded, and a ceiling surface is formed.

  Due to the presence of the passages 20a to 20c, the preforms 22 after the lamination communicate with each other from the gap 36 to the outer peripheral wall. Accordingly, in each preform 22, as shown in FIGS. 3 to 5, gas or liquid is passed through the passages 20 a to 20 c from the gap 36 to the outer peripheral wall or from the outer peripheral wall to the gap 36. Distribution is possible.

  While maintaining this state, the holding mechanism 30 is carried into a heat treatment furnace (not shown) and then carburized. Specifically, first, the temperature of the heat treatment furnace is raised, and when a predetermined temperature is reached, a gas as a carburizing agent (for example, methane gas, propane gas, etc.) is supplied.

  A part of the carburizing gas is in contact with the outer peripheral wall of the preform 22 and then flows to the through hole 12 side through the passages 20a to 20c. That is, the carburizing gas also contacts the bottom wall surfaces, both side wall surfaces, and the ceiling surface of the passages 20a to 20c.

  Here, the ceiling surfaces of the passages 20a to 20c are portions exposed to the passages 20a to 20c in the lower end surface of another preform 22 placed immediately above the preform 22. Therefore, when the carburizing gas flows through the passages 20a to 20c, the carburizing gas is also exposed at the lower end surface of the preformed body 22 just above the passages 20a to 20c of another preformed body 22 and exposed. Contact.

  The carburizing gas that has flowed into the gap 36 via the passages 20a to 20c contacts each internal tooth 18 while descending or rising, and is finally discharged from below or above the gap 36.

  On the other hand, the carburizing gas may flow from below or above the gap 36 and reach the inner teeth 18 of the preform 22. The carburizing gas is discharged to the outer peripheral wall side of the preformed body 22 after passing through the passages 20a to 20c. Accordingly, the carburizing gas is exposed by being positioned on the inner teeth 18, the bottom wall surface and the side wall surfaces of the passages 20 a to 20 c, and part of the lower end surface of another preformed body 22 (directly above the passages 20 a to 20 c of the preformed body 22. Touch the area.

  Each part which carburizing gas contacted as mentioned above, ie, an outer peripheral wall, the bottom wall surface and side wall surface of the channel | paths 20a-20c in an upper end surface, and a part of lower end surface (the channel | paths 20a-20c of the lower preforming body 22) The carbon component which is a constituent element of the carburizing gas enters and diffuses into each surface layer portion of the internal teeth 18 and the exposed portion located directly above the inner teeth 18, and as a result, the surface layer portion is hardened to a predetermined depth. A layer is formed. Thereby, the carburizing process is performed and the spider 10 having a hardened layer is obtained.

  That is, according to the present embodiment, not only the inner teeth 18 of the preform 22 but also the outer peripheral wall and part of the upper and lower end surfaces can be carburized to form a hardened layer. In other words, since a hardened layer can be provided over substantially the entire surface of the preformed body 22, it is possible to suppress the occurrence of a quenching distortion difference in the preformed body 22, and eventually the spider 10 that is the final product.

  After the above steps have been performed, an exhaust step for exhausting the carburizing gas from the interior of the heat treatment furnace, a soaking step for maintaining the temperature inside the heat treatment furnace at a substantially constant quenching holding temperature, and then, A cooling process for cooling the spider 10 to a predetermined temperature is performed.

  The spider 10 taken out from the chamber of the heat treatment furnace is conveyed through a transfer device (not shown) while being passed through the support shaft member 34, and finally, as shown in FIG. Is immersed in the cooling oil (refrigerant) 42 stored in the tank.

  By being left in the cooling oil 42 for a predetermined time, the exposed outer peripheral wall of the spider 10 is suitably cooled by being in contact with the cooling oil 42 in the oil tank 40. On the other hand, the passages 20a to 20c and the internal teeth 18 circulate along the same path as the carburizing gas, in other words, the cooling oil 42 that flows into the passages 20a to 20c from the gap 36 and is discharged to the outer peripheral wall side. Alternatively, the cooling oil 42 which flows into the passages 20a to 20c from the outer peripheral wall side and is discharged into the gap 36 is cooled by contact.

  As the spider 10 is lowered to a predetermined temperature as described above, the quenching process for the spider 10 is performed. Since the cooling oil 42 flowing from the outer peripheral wall side or the gap 36 side flows as described above, the inner teeth 18 existing in the flow path, the bottom wall surfaces of the passages 20a to 20c, both side wall surfaces, and the ceiling surface. It is possible to perform a uniform quenching process.

  After the entire spider 10 has been cooled to a predetermined temperature in this way, the quenching process ends when the spider 10 together with the holding mechanism 30 is pulled out of the oil tank 40 under the action of a transfer device (not shown).

  By the above operation, the quenching distortion difference is suppressed, and for this reason, the spider 10 with good dimensional accuracy is obtained.

  Here, the relationship between the presence / absence of the passages 20a to 20c and the process capability index (CP value) when carburizing and quenching are performed on 30 preforms 22 made of SCM steel and boron steel. As shown in FIG. It means that there are few inferior goods, so that CP value is large. Note that N = 30.

  From FIG. 7, not only SCM steel but also boron steel, which is likely to cause a quenching strain difference, the number of defective products is remarkably reduced by providing the passages 20 a to 20 c and carburizing treatment, in other words, It is clear that the spider 10 having a small quenching distortion difference and excellent dimensional accuracy can be obtained.

  Thus, in this Embodiment, the channel | paths 20a-20c extended from the through-hole 12 to an outer peripheral wall are provided in the upper end surface of the ring part 14 of the preform 20, and carburizing is performed at the time of carburizing process or quenching process. After bringing gas or cooling oil into contact with the inner teeth 18, flow through the passages 20 a to 20 c to the outer peripheral wall, or after contacting the outer wall with carburizing gas or cooling oil, then pass the passages 20 a to 20 c. It is made to distribute | circulate to the internal tooth 18 via. As a result, a hardened layer can be provided not only on the outer peripheral wall of the spider 10 but also on the inner teeth 18 and part of the upper and lower end faces, so that it is possible to avoid the occurrence of a quenching distortion difference in the spider 10. The manufacturing yield of 10 can be improved.

  In the above-described embodiment, the case where the carburizing process is performed on the preformed body 22 to be the spider 10 constituting the tripod type constant velocity joint has been described. Any member may be used as long as it has internal teeth in the through hole.

  Further, the number of the preforms 22 passed through the support shaft member 34 is not particularly limited, and may be 5 or less or 5 or more. The number of passages is not limited to three, and the number of passages may be set to nine, for example, by providing passages 20a to 20h as shown in FIG.

  Furthermore, the present invention is particularly suitable when the internal gear member is made of a material that is difficult to ensure dimensional accuracy because of a relatively large quenching distortion difference such as boron steel. The material of the internal tooth member is not limited to these, and any material may be used. For example, case-hardened steel may be used.

  Furthermore, the preforms 22 may be stacked so that the end surfaces provided with the passages 20a to 20c face downward, and the passages 20a to 20c are formed on the upper end surface of the preform 22 as shown in FIG. While providing 20c, you may make it provide channel | paths 20d-20f in a lower end surface. In this case, it is not particularly necessary to match the positions of the passages 20a to 20c on the upper end surface with the positions of the passages 20d to 20f on the lower end surface. Of course, the number of passages may be different between the upper end surface and the lower end surface.

  When the preforms 22 are stacked, it is not particularly necessary to align the positions of the passages 20a to 20c, and may be irregular as shown in FIG. Even in this case, the passages 20a to 20c are not blocked by the one end surface of the preform 22 directly above the passages 20a to 20c. Therefore, the flow of the carburizing gas from the outer peripheral wall side to the inner teeth 18 or the flow from the inner teeth 18 to the outer peripheral wall side is not hindered, and eventually each preform 22 is subjected to carburizing treatment. .

It is a schematic whole perspective view of the spider as an internal tooth member concerning this embodiment. It is a partially-omission perspective view of the holding mechanism for implementing the manufacturing method of the internal toothed member which concerns on this Embodiment. It is a perspective view which shows the state which laminated | stacked the several preforming body by the holding mechanism shown in FIG. It is a longitudinal cross-sectional view of FIG. FIG. 4 is a plan view of FIG. 3. It is schematic operation | movement explanatory drawing at the time of cooling with an oil tank in the state hold | maintained at the holding mechanism with the heated spider. It is a graph which shows the relationship between the presence or absence of a channel | path, and CP value. It is a schematic whole perspective view of the spider provided with nine passages. It is a schematic whole perspective view of the spider provided with three passages on the upper and lower end faces. It is a perspective view which shows the state which laminated | stacked the some preforming body irregularly with the holding mechanism shown in FIG. It is a general whole perspective view of a general spider. It is a graph which shows the relationship between a lamination position and a quenching distortion difference.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 10 ... Spider (internal tooth member) 2, 12 ... Through-hole 3, 18 ... Internal tooth 14 ... Ring part 16a-16c ... Trunnion 20a-20h ... Channel 22 ... Pre-formed body 30 ... Work holding mechanism 32 ... Frame Body 34 ... support shaft member 36 ... gap 40 ... oil tank 42 ... cooling oil

Claims (4)

An internal tooth member having a ring portion provided with a through hole and having inner teeth formed on an inner peripheral wall of the through hole;
A passage extending from the through hole to the outer peripheral wall is provided on at least one of the both end faces of the ring portion where the through hole opens.
Carburizing treatment is performed on at least the inner teeth and the passage ,
The internal tooth member is a spider constituting a constant velocity joint . A method for producing an internal toothed member having a ring portion provided with a through hole and carburizing a molded body in which internal teeth are formed on the inner peripheral wall of the through hole to obtain an internal toothed member. There,
As the molded body, a step of providing a passage extending from the through hole to the outer peripheral wall on at least one end face of the ring portion where the through hole opens, and
A step of laminating the molded bodies by passing the through-holes of a plurality of the molded bodies through a shaft member standing on a base so that end surfaces provided with the passages face the same direction;
The laminated compact is heated in a heat treatment furnace, a carburizing agent is supplied into the heat treatment furnace, and the carburizing agent is passed through the passage or the through hole of the compact, and the carburizing agent is passed through the through hole or the passage. The process of discharging from the
Have
A method of manufacturing an internal tooth member, wherein at least the internal teeth and the passage are carburized with a carburizing agent that has reached the passage or the through hole. 3. The manufacturing method according to claim 2 , wherein after the carburizing treatment is finished, the plurality of molded bodies are immersed in a cooling medium in a stacked state, and the cooling medium is passed through the through holes or the passages. A method for producing an internal toothed member, characterized in that it is circulated to the passage or the through hole. The manufacturing method according to claim 2 or 3 , wherein a spider that constitutes a constant velocity joint is manufactured as the internal tooth member.

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