JP2009285772A - Method of manufacturing gear plate for reclining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing, without relying upon cutting, a hardened gear plate smoothly rotatable in a base plate. <P>SOLUTION: This gear plate for a reclining device is manufactured via the following three steps: (A) a forming step for forming the gear plate for a reclining device in a desired shape, (B) a heat treatment step for applying a heat treatment to the formed gear plate, and (C) a burnishing step for applying a burnishing treatment to the outer peripheral surface of the heat-treated gear plate using a rolling burnishing device. The rolling burnishing device comprises a work receiving section 20 for rotatably supporting the gear plate 3 and three rollers 13, 14, 15 pressing the outer periphery of the gear plate supported on the work receiving section from three directions. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a gear plate, which is a component of a vehicle seat reclining device. In particular, the present invention relates to a manufacturing method of a gear plate for a reclining device that can mass-produce a gear plate excellent in smoothness of an outer peripheral surface more efficiently than before.

  The seat mounted on the vehicle and used as the front seat is adjustable in the inclination angle of the seat back (backrest part) with respect to the seat cushion (seat part) in order to achieve the optimum driving posture (driving position) . A reclining device is provided at a connecting portion between the seat cushion and the seat back as a mechanism that enables the tilt angle adjustment. There are various reclining methods. In Japan, a round type reclining device as shown in an exploded perspective view of FIG. 4 is common.

  As an example, the reclining device shown in FIG. 4 includes a shaft 1, a base plate 2, a gear plate 3, a plate connecting ring cover (not shown), and other members (link plate 6, lock gear 7, etc.). Is provided as a unit obtained by assembling. In this unit, the gear plate 3 is rotatably accommodated in the base plate 2 with the outer peripheral surface of the gear plate 3 contacting the inner peripheral surface of the outer peripheral annular portion of the base plate 2. For this reason, it is required that the gear plate 3 can smoothly rotate in the base plate 2 and that the gear plate 3 is excellent in wear resistance and the like.

[Conventional manufacturing method]
Conventionally, a gear plate has been manufactured by the following procedure. That is, first, a gear plate having a desired shape is formed by punching and pressing a material steel plate. Next, the formed gear plate is sequentially fed into a continuous heating furnace, and the plurality of gear plates are continuously heated to a predetermined temperature. Subsequently, the heated gear plate that has passed through the continuous heating furnace is sequentially dropped into an oil bath at room temperature and quenched to quench the surface of the gear plate. Thus, the surface of the gear plate is hardened to improve the wear resistance. The reason why the continuous heating furnace is used instead of the batch-type heating furnace for heating is to ensure the uniformity of the heating temperature and to avoid variations in the hardenability between lots.

  However, although a continuous heating furnace is used from the viewpoint as described above, on the other hand, fine dents remain on the outer peripheral surface of the gear plate after quenching, and the surface accuracy (surface smoothness) is low. There were drawbacks. This is because it is inevitable that the gear plates collide or interfere with each other and damage each other when the gear plates are taken in and out of the continuous heating furnace or during conveyance in the furnace. In addition, there is a problem that the roundness of the outer peripheral portion of the gear plate is impaired due to thermal strain accompanying the quenching process. Deterioration of the outer peripheral surface accuracy due to dents and deformation due to thermal strain hinder smooth rotation of the gear plate within the base plate.

  For this reason, in the conventional method, the smoothness and the roundness of the outer peripheral surface of the gear plate are ensured by cutting the outer peripheral surface of the gear plate after quenching with an NC lathe. That is, in order to obtain a gear plate that can rotate smoothly in the base plate, cutting after heat treatment such as quenching has been essential.

As a result of conducting a prior art search in preparation of the present application, the following two prior art documents were found as general techniques in the field of metal processing.
JP-A-48-47472 (Metal Rolling Burnishing Method) Japanese Patent Application Laid-Open No. 51-95973 (Hot Forming Method for Rings)

  However, there are various problems in the cutting that is essential in the conventional method. For example, generation of cutting waste and its processing problem, problem of consumption of the cutting tip itself, consumption of cutting oil and its scattering, problem of ignition by sparks during cutting, problem of requiring considerable time for cutting, etc. It is. Therefore, there has been a demand for a method for correcting a quenched gear plate that does not involve cutting.

  An object of the present invention is to provide a method for manufacturing a quenched gear plate that can be smoothly rotated in a base plate without relying on cutting.

The present invention is a method of manufacturing a gear plate for a reclining device,
A) a molding process for molding a gear plate for a reclining device into a desired shape;
B) a heat treatment process for heat-treating the molded gear plate;
C) A burnishing step of performing burnishing on the outer peripheral portion of the heat-treated gear plate using a rolling burnishing device.
The technical significance of each constituent element in this method and the more preferable technical limitation will be described in detail in the section “Best Mode for Carrying Out the Invention” below.

  In the present invention, after the heat treatment, a non-cutting process of applying a burnishing process to the outer peripheral portion of the gear plate by using a rolling burnishing device is employed, which causes a problem in the conventional cutting process. Therefore, it is possible to manufacture a quenched gear plate that can smoothly rotate within the base plate while ensuring the smoothness of the outer peripheral surface of the gear plate and the roundness of the gear plate.

  A manufacturing method of a gear plate for a reclining device according to the present invention includes at least three steps of a molding step, a heat treatment step, and a burnishing process.

  The forming step (A) as the first step is a step of forming the gear plate into a desired shape. Specific examples of the forming method include punching press processing and die casting in which a metal plate material used as a material is punched with a press machine, but are not limited thereto. Further, the molding process does not have to be a single process, and may include a plurality of different types of processes, for example, a turning process using a lathe may be included in part. As a constituent material of the gear plate, a quenchable metal such as an iron-based material (for example, boron steel) is used.

  The heat treatment step (B) as the second step is a step of performing a heat treatment on the gear plate obtained in the molding step. Examples of specific heat treatment include quenching and tempering. The heat treatment step is preferably a quenching step, and the quenching step continuously heats a plurality of the formed gear plates using a continuous heating furnace in which the furnace is set to a predetermined heating temperature. It is preferable to comprise a heating step (b1) and a cooling step (b2) in which the individual gear plates heated in the continuous heating furnace are cooled and quenched. The cooling step (b2) is more preferably a bath cooling step in which the individual gear plates heated in the continuous heating furnace are dropped into a cooling bath (for example, an oil bath) and quenched.

  When the heat treatment step (B) is a quenching step and the quenching step includes a heating step (b1) using a continuous heating furnace, when the gear plate is taken in and out of the continuous heating furnace or in the furnace Needless to say, the necessity or usefulness of the present invention is very high, because it is inevitable that the gear plates collide or interfere with each other during the transfer.

  The burnishing step as the third step is a step of performing burnishing on the outer peripheral portion of the gear plate obtained in the heat treatment step using a rolling burnishing device.

  Examples of the rolling burnishing device used in the burnishing process include devices as shown in FIGS. 1 and 2. That is, the illustrated rolling burnishing device includes a fixed splate 11 as a fixed base and a movable plate 12 provided on the fixed plate 11 so as to be horizontally movable in the front-rear direction. The movable plate 12 is provided with a workpiece receiving portion 20 for rotatably supporting the gear plate 3 as a workpiece (workpiece).

  The workpiece receiving portion 20 is restricted from being displaced upward by a rotary pedestal 21 that supports the gear plate 3 from below, a central shaft 22 provided in a central region of the rotary pedestal 21, and a head portion of the central shaft 22. And a thrust washer 23 at least. By setting the gear plate 3 to the work receiving portion 20 so as to be interposed between the rotary base 21 and the thrust washer 23, the gear plate 3 is rotatably supported by the work receiving portion 20. The thrust washer 23 whose upward displacement is restricted by the head portion of the central shaft 22 restricts the movement of the gear plate 3 that tends to escape by receiving the roller pressing force during the burnishing process. It is prevented from detaching from the receiving portion 20.

  A bush (tubular member) 24 through which the central shaft 22 is inserted is provided at the center of the rotary base 21. The inner diameter of the bush 24 is set to be slightly larger than the outer diameter of the shaft portion of the central shaft 22, and a slight gap is secured between the two. That is, the rotation axis of the gear plate 3 set on the workpiece receiving portion 20 can be displaced in the horizontal direction by the gap. For this reason, the gear plate 3 on the workpiece receiving portion 20 can freely rotate on the roller reference (in other words, the outer peripheral reference of the gear plate 3) during the burnishing without being restricted by the central shaft 22.

  The movable plate 12 is provided with a pair of left and right load rollers 13 and 14. These two load rollers 13 and 14 are rotatable in a state of circumscribing the outer peripheral surface of the gear plate 3. A driving roller 15 is provided on the front side of the fixed plate 11 and the movable plate 12. The drive roller 15 is operatively connected to a drive source 16 (for example, a lathe drive motor), and can be forcibly rotated in a state of circumscribing the outer peripheral surface of the gear plate 3. The four members of the gear plate 3, the left and right load rollers 13, 14 and the driving roller 15 supported by the work receiving portion 20 are such that three outer contacts of the gear plate and the three rollers are equal to the central axis of the gear plate 3. Relative positioning is carried out so that it may become an angle interval (namely, 120 degree interval).

  Further, an urging mechanism 30 for urging the entire movable plate 12 toward the drive roller 15 is provided at the rear portion of the fixed plate 11. The urging mechanism 30 includes a plurality of coil springs 33 interposed between a standing wall 31 at the rear end of the fixed plate 11 and a standing wall 32 at the rear end of the movable plate 12. By this urging mechanism 30, the pair of load rollers 13 and 14 and the gear plate 3 are pressed against the drive roller 15 together with the movable plate 12. Based on this pressing action, the outer peripheral surface of the gear plate 3 on the workpiece receiving portion 20 is evenly pressed by the three rollers 13, 14, 15. Further, based on the frictional contact between each roller and the gear plate, the rotation of the driving roller 15 is also transmitted to the gear plate 3 and the two load rollers 13 and 14, and along with the forced driving of the driving roller 15, the gear plate 3. And the two load rollers 13 and 14 are driven to rotate. In this way, the outer peripheral surface of the gear plate 3 supported by the workpiece receiving portion 20 is burnished by the three rollers 13, 14, 15.

  By burnishing using such a rolling burnishing device, the dents generated on the outer peripheral surface of the gear plate 3 are eliminated by pressing the entire surface by the three rollers 13, 14, 15, and the outer peripheral surface of the gear plate 3 is Finished with surface accuracy (surface roughness) according to the surface accuracy of the roller. Further, the shape correcting action by the three rollers 13, 14, 15 eliminates the deformation of the gear plate 3 due to the thermal strain during the heat treatment, and the gear plate 3 can regain its ideal roundness.

  Hereinafter, an embodiment of the present invention and a comparative example compared with the embodiment will be described.

[Example]
Plate-shaped boron steel (SCS22CB) was prepared and punched with a press machine to obtain a gear plate (diameter: 70 mm) having a shape as shown in FIG. Next, a plurality of the gear plates obtained in this way were sequentially put into a continuous heating furnace whose furnace temperature was set to about 800 ° C., and these were continuously heated. The time for one gear plate to stay in the continuous heating furnace is about 60 minutes. And the gear plate which came out of the exit of a heating furnace was dropped quickly into the oil bath at normal temperature, and the gear plate in the heated state was quenched and quenched. When the outer peripheral surface of the gear plate cooled in the oil bath was observed with a microscope, very fine dents were observed. By this quenching, the outer peripheral portion of the gear plate was cured to a level of about 700 to 800 Hv in terms of Vickers hardness.

Subsequently, after taking out from the oil bath, burnishing was performed on each gear plate that had been drained using a rolling burnishing device of the type shown in FIGS. 1 and 2. Processing conditions (conditions for three-point roller molding) at that time are as follows.
Work speed: 870 [rpm]
Molding load (pressing force of each roller): 1700 [N]
Molding time (load and rotation application time): 10 [seconds]

  In this way, 80 specimens (No. 1 to 80) of the gear plate of this example were obtained. Then, the smoothness of the outer peripheral surface of each gear plate and the roundness of the gear plate were evaluated for these 80 specimen gear plates by the following evaluation method. That is, each gear plate was incorporated in the base plate to complete the unit, and the rotational torque value of the completed unit was measured. The rotational torque value is a realistic index regarding the smoothness of the outer peripheral surface of the gear plate and the roundness of the gear plate. That is, it can be evaluated that the smaller the rotational torque value, the higher the smoothness of the outer peripheral surface and the higher the roundness of the gear plate. The measurement result of the rotational torque value for 80 samples according to this example is shown in the graph of FIG.

[Comparative example]
A gear plate was molded under the same conditions as in the above example and quenched under the same conditions, but then not burned as in the above example (that is, without three-point roller molding) 80 specimens (Nos. 1 to 80) were obtained as the gear plate of Example. And the rotational torque value of the unit which used the gear plate of this comparative example was measured by the same evaluation method as the said Example. The measurement result of the rotational torque value for 80 samples according to this comparative example is shown in the graph of FIG.

[Consideration of measurement results]
As can be seen from the graph of FIG. 3, for the 80 specimens according to the example, the rotational torque value is distributed in a relatively narrow range between 0.1 and 0.3 [Nm], and an average of about A low value of about 0.2 Nm was shown. On the other hand, for the 80 samples according to the comparative example, the rotational torque value is not only distributed over a wide range between 0.3 and 1.0 [Nm], but is also clearly higher than that of the example. Indicated. This measurement result shows that the gear plate of the example has very little catch during rotation compared to the gear plate of the comparative example. In other words, the gear plate of the example subjected to the burnishing process by the rolling burnishing device is superior to the smoothness of the outer peripheral surface and the roundness of the gear plate itself as compared with the gear plate of the comparative example not subjected to the burnishing process. It can be said that.

FIG. 2 is a schematic plan view of a rolling burnishing device. The longitudinal cross-sectional view of the principal part of a rolling compaction burnishing apparatus. The graph of the measurement result of the rotational torque value regarding the quality evaluation of a gear plate. The disassembled perspective view of the reclining apparatus as an example.

Explanation of symbols

2 Base plate 3 Gear plate (workpiece)
13 Left load roller 14 Right load roller 15 Drive roller 20 Work receiving portion 30 Biasing mechanism

Claims (3)

A) a molding process for molding a gear plate for a reclining device into a desired shape;
B) a heat treatment process for heat-treating the molded gear plate;
C) a burnishing step of performing burnishing on the outer peripheral portion of the heat-treated gear plate using a rolling burnishing device;
A method of manufacturing a gear plate for a reclining device. The heat treatment step (B)
b1) A heating step of continuously heating a plurality of the formed gear plates using a continuous heating furnace in which the inside of the furnace is set to a predetermined heating temperature;
2. The manufacturing of a gear plate for a reclining device according to claim 1, further comprising a quenching step comprising: b2) a cooling step of cooling and quenching the individual gear plates heated in the continuous heating furnace. Method. The rolling burnishing device comprises:
A work receiving part (20) for rotatably supporting the gear plate as a work, and three rollers (13, 14, 15) capable of pressing the outer peripheral part of the gear plate supported by the work receiving part from three directions And
Burning the outer peripheral portion of the gear plate while forcibly driving one of the three rollers to rotate the gear plate and the remaining two rollers.
The workpiece receiving portion is configured to allow the gear plate to rotate on a roller basis during burnishing by the three rollers.
The manufacturing method of the gear plate for reclining apparatuses of Claim 1 or 2.

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