JP2005299706A - Worm and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a worm provided with a configuration for eliminating breakage of a roll die and capable of increasing its rigidity and dispensing with deburring at a gear cutting start point and a gear cutting end point. <P>SOLUTION: In this worm having one or a plurality of teeth, diameter D1, D1 of root circle of end parts H1, H1 of facewidth H is cut to be smaller than diameter D2 of root circle of a central part H2 of facewidth H, a tooth shape of a tooth in the central part H2 having large diameter of root circle can be finished by rolling, and teeth of the end parts H1, H1 are not rolled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a worm and a manufacturing method thereof.

  A worm having one or more teeth is cut by cutting or formed by rolling (for example, Patent Document 1). A manufacturing method is also known in which a tooth profile is finished by rolling after roughly cutting teeth by cutting.

  FIG. 4 is an explanatory view of a conventional manufacturing method for finishing a tooth profile of a tooth cut by rolling. In the manufacturing method of finishing the tooth profile of the chopped teeth by rolling, one shaft portion of an element body 10 (see a in FIG. 4) made of a right circular cylinder member having a shaft portion is attached to a lathe chuck, The one or more teeth 10a are roughly cut with a cutting blade while rotating the body 10 (see b in FIG. 4), and then the teeth are cut between a pair of roll dies having teeth corresponding to the teeth of the worm. The base body 10 is interposed, one roll die is moved in the direction of the other roll die while rotating each roll die, and the tooth 10a is formed by finishing the tooth profile of the base body 10.

  By the way, in the manufacturing method that finishes the tooth profile of the tooth 10a that has been cut off by rolling, the finish surface of the roll die is pressed against the tooth surface of the roughly ground tooth 10a to finish it into an accurate tooth profile. The element body 10 moves slightly in the tooth trace direction, and as a result, the element body 10 moves in the axial direction with respect to the roll die. As the movement in the direction of the tooth trace progresses, the non-tooth portions 10b, 10b exceeding the tooth width interfere with the roll die, and the roll die is damaged.

FIG. 5 is an explanatory view of a conventional manufacturing method for avoiding breakage of a roll die. In order to avoid breakage of the roll die, the annular grooves 10c and 10c having a diameter equal to the root circle diameter are cut between the non-tooth portions 10b and 10b provided in the portion exceeding the tooth width H and the tooth width H. What is necessary is just to form by processing. By providing the annular grooves 10c and 10c, when the base body 10 moves in the tooth trace direction with respect to the roll die in the step of finishing the tooth profile of the roughly cut teeth 10a by rolling, the non-tooth portions 10b and 10b Can be prevented from interfering with the roll die, and damage to the roll die can be prevented.
Japanese Patent Laid-Open No. 10-175036

  However, in the worm in which the element body 10 is provided with the annular grooves 10c and 10c, the number of steps is increased because the processing steps of the annular grooves 10c and 10c are necessary separately from the gear cutting process and the rolling process. However, there is a problem that the manufacturing cost is increased, and since the annular grooves 10c and 10c are provided in the portion exceeding the tooth width H, there is a problem that the rigidity of the worm is lowered, and the tooth width H Since the teeth at both ends are also rolled, the edges of the tooth cutting start point and the gear cutting end point become sharp, and deburring of this sharp part is necessary.

  The present invention has been made in view of such circumstances, and can increase the rigidity of the worm having a configuration capable of eliminating the breakage of the roll die. The object is to provide a worm that does not need to be removed. Moreover, it aims at providing the manufacturing method which can manufacture a worm | warm with high rigidity, without damaging a roll die by a gear cutting process and a rolling process.

  The worm according to the first invention is characterized in that the root diameter at the end of the tooth width is smaller than the diameter at the center of the tooth width.

  In the first invention, since the center portion of the tooth width having a large root circle diameter can be a rolled finish tooth, and the end of the tooth width can be configured as a non-rolled portion tooth, Worm with a structure that can eliminate the damage to the roll die can be made higher than that provided with an annular groove, and the worm has no burrs at the gear cutting start point and gear cutting end point. Can be obtained.

  The worm according to the second invention is characterized in that, in the worm having a non-tooth portion at a position beyond the tooth width, the root circle diameter at the end of the tooth width is smaller than the root circle diameter at the center portion of the tooth width. And

  In the second invention, the center part of the tooth width having a large root circle diameter can be a rolled finish tooth, and the end of the tooth width can be configured as a non-rolled part tooth. Worm with a structure that can eliminate the damage to the roll die can be made higher than that provided with an annular groove, and the worm has no burrs at the gear cutting start point and gear cutting end point. Can provide.

  In the method for manufacturing a worm according to the third aspect of the present invention, after the root diameter of the end of the tooth width is cut to be smaller than the diameter of the root circle at the center of the tooth width, the tooth profile of the tooth at the center is formed. It is characterized by finishing by rolling.

  In the third invention, teeth having different root diameters can be formed by changing the position of the cutting blade during gear cutting, and the amount of movement of the worm in the tooth trace direction during rolling Can be ensured in a portion having a small diameter of the root circle, so that a worm having high rigidity can be manufactured by the gear cutting process and the rolling process without damaging the roll die. Moreover, since the end portion of the tooth width can be non-rolled, a worm having no burrs at the gear cutting start point and gear cutting end point can be manufactured.

  According to the first and second inventions, it is possible to increase the rigidity of the worm having a configuration capable of eliminating the breakage of the roll die, and to provide a worm having no burr at the gear cutting start point and the gear cutting end point. Can be obtained.

  According to the third invention, the gear cutting step and the rolling step can produce a worm having no burr at the gear cutting start point and gear cutting end point without damaging the roll die, and the manufacturing cost can be reduced. .

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a front view of the worm.
The worm extends in the axial direction from the tooth portion 1 having a plurality of teeth 1a, the non-tooth portions 2 and 2 provided at positions exceeding the tooth width H of the tooth portion 1, and the non-tooth portions 2 and 2. It has the protruding shaft parts 3 and 3. The tooth portion 1 is formed such that the root circle diameter D1 of the end portions H1 and H1 of the tooth width H is smaller than the root circle diameter D2 of the center portion H2 of the tooth width H. Further, center holes 3 a and 3 a are provided in the center of the end surfaces of the shaft portions 3 and 3, and a spline 3 b is provided in the outer peripheral portion of the one shaft portion 3.

FIG. 2 is an explanatory view showing the manufacturing process of the worm, and FIG. 3 is a schematic view of the rolling device.
The worm is manufactured by roughly cutting the outer peripheral portion of the body made of a right circular cylindrical member having the shaft portions 3 and 3 by a gear cutting means such as a lathe (see FIG. 2 (a)), and then a rolling device. To finish the teeth by rolling (see Fig. 2 (b)).

  In gear cutting, one shaft portion 3 of the element body is attached to a lathe chuck, and a cutting blade formed in a tooth profile slightly smaller than the finished tooth profile of the tooth 1a is rotated while the element body is rotated. The teeth having a tooth width H are formed by moving in the radial direction and the axial direction, and the non-tooth portions 2 and 2 are formed at positions exceeding the tooth width H. In this case, by cutting the radial movement amount of the cutting blade at the end portions H1 and H1 exceeding the central portion H2 which is the effective tooth width, more than the radial movement amount at the central portion H2. The root diameter D1 of the end portions H1 and H1 is smaller than the root diameter D2 of the central portion H2. The difference between the root diameters D1 and D2 of the end portions H1 and H1 and the central portion H2 is set to a dimension necessary for finishing the tooth profile of the central portion H2 by rolling. Therefore, the tooth profile of the end portions H1, H1 and the central portion H2 is the same, and the root circle diameters D1, D2 and the reference pitch circle diameter are different.

  Rolling of the worm tooth 1a is performed between a pair of roll dies 41, 42 having a forming blade formed in a tooth finish tooth profile on the outer peripheral portion and spaced apart in the radial direction, and the roll dies 41, 42. Using the rolling device 4 provided with an element base 43, one roll die 41 is moved in the direction of the other roll die 42 while rotating each roll die 41, 42, and between each roll die 41, 42. The tooth profile of the central portion H2 is finished by rolling the tooth portion with the element body sandwiched therebetween. In this case, the ends H1 and H1 having a reduced root circle diameter are not rolled. Accordingly, the teeth of the central portion H2 have a high-precision tooth profile finished by rolling, and the teeth of the end portions H1 and H1 have a tooth profile cut out. Each roll die 41, 42 has a roll width slightly longer than the effective tooth width of the central portion H2.

  As described above, when rolling the central portion H2 of the tooth width H by the rolling device 4, the element body between the roll dies 41 and 42 moves little by little in the tooth trace direction, and as a result, the element body rolls. Although it moves in the axial direction with respect to the dies 41, 42, the end portions H 1, H 1 at positions beyond the central portion H 2 of the tooth width H have a small root circle diameter. 42, and the end portions H1 and H1 at positions beyond the central portion H2 of the tooth width H are not rolled, so that the tooth thickness at the start point and end point is rolled. Therefore, burrs can be prevented from occurring at the start point and end point.

  In the embodiment described above, the non-tooth portions 2 and 2 are provided at both positions exceeding the tooth width H, but the non-tooth portion 2 is provided only at one position exceeding the tooth width H. It is good also as a structure which made the tooth root circle diameter D1 of the edge part H1 of the tooth width H at least the non-tooth part 2 side smaller than the tooth root circle diameter D2 of the center part H2, and both positions exceeding the tooth width H It is good also as a structure which made the root circle diameter D1 of at least one edge part H1 of the tooth width H smaller than the root circle diameter D2 of the center part H2, without providing the non-tooth part 2 and 2. Thus, even when the root diameter D1 of one end H1 is reduced, the tooth width H is longer than the effective tooth width, so that the rigidity of the worm can be increased.

It is a front view of the worm | warm which concerns on this invention. It is explanatory drawing which shows the manufacturing process of the worm | warm which concerns on this invention. It is a schematic diagram of the rolling apparatus used for manufacture of the worm | warm which concerns on this invention. It is explanatory drawing of the conventional manufacturing method which finishes the tooth profile of the chopped tooth by rolling. It is explanatory drawing of the conventional manufacturing method for avoiding the failure | damage of a roll die.

Explanation of symbols

H tooth width H1 end H2 center D1, D2 root diameter 2 non-tooth

Claims (3)

  A worm characterized in that the root diameter at the end of the tooth width is smaller than the diameter at the center of the tooth width.   A worm having a non-tooth portion at a position beyond the tooth width, wherein the root diameter at the end of the tooth width is smaller than the diameter at the center of the tooth width.   A worm characterized in that the root diameter of the end of the tooth width is cut to be smaller than the diameter of the root circle at the center of the tooth width and then the tooth profile of the center is finished by rolling. Manufacturing method.

Images