JP2007205365A - Bevel gear and its forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bevel gear and its forming method for preventing a shaft from giving influences to tooth machining work for a gear while preventing looseness between the gear and the shaft assembled together due to frequent use of the bevel gear. <P>SOLUTION: A connection site between a cylindrical portion 18 of the gear 12 and one axial end of the shaft 20 is provided at a position where it is set back from a moving track line L of a machining device when machining teeth 16 of the gear 12. This prevents the interference of the cylindrical portion 18 of the gear 12 and the shaft 20 with the movement of the machining device when cutting the teeth 16 of the gear 12 before connected to the shaft 20. The cylindrical portion 18 of the gear 12 and one axial end of the shaft 20 are connected together at the connection site with friction pressure contact, and so the cylindrical portion 18 of the gear 12 can be firmly connected to one axial end of the shaft 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bevel gear, and more particularly, to a bevel gear (bevel gear) constituting a gear transmission device such as a final reduction gear used in a large motorcycle and a method for forming the bevel gear.

  2. Description of the Related Art Conventionally, bevel gears are used in gear transmission devices such as final reduction gears used in large motorcycles in order to transmit rotational driving force between two axes that intersect at substantially right angles. The bevel gear includes a cylindrical shaft portion serving as a rotation shaft core and a gear portion (gear tooth forming portion) that meshes with another bevel gear. And this axial part and the gear part are integrally formed from a viewpoint of ensuring intensity | strength (refer the following patent document 1).

  However, when the shaft portion and the gear portion are integrally formed, the cylindrical shaft portion protrudes toward the tooth surface forming side when the gear portion is geared later by a processing device such as a gear cutter, and the processing device is moved. There arises a problem that the processing is restricted and hinders the processing work.

In order to solve this problem, a bevel gear is conventionally known in which a shaft portion and a gear portion are separately formed, and both are assembled by press-fitting in a subsequent process (see Patent Document 2 below). According to this bevel gear, the teeth of the gear portion are processed by the processing device before the shaft portion and the gear portion are assembled, and both are assembled after the teeth of the gear portion are processed. It is possible to prevent the part from becoming an obstacle.
Japanese Utility Model Publication No. 61-36338 JP-A-7-198000

  However, in a bevel gear in which the shaft portion and the gear portion are separately formed and are integrally assembled by press-fitting or the like, there is a problem in durability that the assembly of the gear portion to the shaft portion is loosened due to the frequency of use of the bevel gear. If the assembly of the gear portion with respect to the shaft portion is loosened, when the driving force is transmitted in the bevel gear, play occurs and smooth drive connection cannot be achieved, resulting in a decrease in durability.

  Therefore, in consideration of the above circumstances, the present invention can prevent the shaft portion from affecting the machining operation of the teeth of the gear portion, and can assemble the gear portion and the shaft portion without affecting the frequency of use of the bevel gear. It is an object of the present invention to provide a bevel gear that can be held firmly and stably and a method for forming the same.

  The invention according to claim 1 includes a gear portion having teeth meshing with another gear, and a cylindrical shaft portion connected to the cylindrical portion of the gear portion, and rotational movement between two intersecting axes. A connecting portion between the cylindrical portion and the shaft portion of the gear portion is provided at a position retracted from a movement trajectory line of a processing apparatus when the teeth of the gear portion are processed. It is characterized by being.

  According to the first aspect of the present invention, the connecting portion between the cylindrical portion and the shaft portion of the gear portion is provided at a position retracted from the movement trajectory line of the processing apparatus when processing the teeth of the gear portion. When the teeth of the gear portion before being connected to the shaft portion are processed, it is possible to prevent the cylindrical portion and the shaft portion from interfering with the movement of the processing apparatus. As a result, it is possible to prevent the cylindrical portion and the shaft portion from affecting the processing operation of the gear portion teeth.

  According to a second aspect of the present invention, in the bevel gear according to the first aspect, the cylindrical portion and the shaft portion of the gear portion are connected by friction welding at the connection portion. .

  According to the second aspect of the present invention, since the cylindrical portion of the gear portion and the shaft portion are connected by friction welding at the connection site, the cylindrical portion of the gear portion and the shaft portion are firmly connected. Can do. Thereby, it can prevent that the assembly | attachment of the cylindrical part of a gear part and a shaft part loosens and rattles irrespective of the usage frequency of a bevel gear.

  The invention according to claim 3 includes a gear portion having teeth meshing with another gear, and a cylindrical shaft portion inserted into and connected to a recess formed in the gear portion, and intersecting two axes A bevel gear that transmits rotational motion between the recesses, the recess being formed at a position retracted from a movement trajectory line of a processing apparatus when processing the teeth, and a space outside the recess in the radial direction of the recess. And the shaft portion is inserted into the concave portion of the gear portion and connected by friction welding, and a beam generated by the friction welding enters the space portion and the shaft portion is detached from the gear portion. It is characterized by preventing.

  According to the third aspect of the present invention, the recess is formed at a position retracted from the movement trajectory line of the processing apparatus when processing the teeth, and the space is formed on the radially outer side of the recess of the gear unit. The shaft portion is inserted into the concave portion of the portion and connected by friction welding. Thereby, a gear part and a shaft part can be connected firmly and it can prevent loose | attaching the assembly | attachment of the cylindrical part and shaft part of a gear part irrespective of the usage frequency of a bevel gear. At the same time, since the flash generated by the friction welding enters the space portion, it is possible to reliably prevent the shaft portion from coming off from the gear portion in the axial direction. Further, by effectively using the flash generated by the friction welding to prevent the shaft portion from coming off, the operation of removing the flash becomes unnecessary.

  According to a fourth aspect of the present invention, there is provided a gear portion having teeth meshing with other gears, and a cylindrical shaft portion connected to the cylindrical portion of the gear portion, and rotational movement between two intersecting axes. A method of forming a bevel gear that transmits a toothed portion, wherein the cylindrical portion of the gear portion and the shaft portion are connected to a position retracted from a movement trajectory line of a processing apparatus when the teeth of the gear portion are processed. Is provided, and the cylindrical portion of the gear portion and the shaft portion are connected at the connection portion.

  According to the fourth aspect of the present invention, the connecting portion between the cylindrical portion and the shaft portion of the gear portion is provided at a position retracted from the movement trajectory line of the processing apparatus when processing the teeth of the gear portion. When the teeth of the gear portion before being connected to the shaft portion are processed, it is possible to prevent the cylindrical portion and the shaft portion from interfering with the movement of the processing apparatus. As a result, it is possible to prevent the cylindrical portion and the shaft portion from influencing the gear cutting operation of the gear portion.

  The invention according to claim 5 includes a gear portion having teeth meshing with another gear, and a cylindrical shaft portion inserted into and connected to a recess formed in the gear portion, and intersecting two axes A method of forming a bevel gear that transmits rotational movement between the first recess and the recess, wherein the recess is formed at a position retracted from a movement trajectory line of a processing apparatus when processing the teeth; A second forming step of forming a space portion on the radially outer side of the concave portion, a connecting step in which the shaft portion is inserted into the concave portion of the gear portion and connected by friction welding, and the friction welding in the connecting step. And a step of preventing the generated flash from entering the space portion and preventing the shaft portion from coming off from the gear portion.

  According to invention of Claim 5, a recessed part is formed in the position retracted | saved from the movement trace line of the processing apparatus at the time of processing a tooth in a 1st formation process. In the second forming step, a space portion is formed on the radially outer side of the concave portion of the gear portion. In the connecting step, the shaft portion is inserted into the concave portion of the gear portion and connected by friction welding. In the disconnection preventing step, the flash generated by the friction welding in the connecting step enters the space portion, thereby preventing the shaft portion from coming off from the gear portion. Thereby, a gear part and a shaft part can be firmly connected and it can prevent simply that the assembly | attachment of the cylindrical part and shaft part of a gear part loosens irrespective of the usage frequency of a bevel gear. At the same time, since the flash generated by friction welding enters the space portion, it is possible to reliably prevent the shaft portion from coming off from the gear portion in the axial direction. Further, by effectively using the flash for preventing the shaft from coming off, the work for removing the flash becomes unnecessary.

  According to the present invention, it is possible to prevent the shaft portion from affecting the machining operation of the teeth of the gear portion, and it is also possible to easily prevent the connection between the gear portion and the shaft portion from being loosened due to the frequency of use of the bevel gear.

  Next, a bevel gear according to a first embodiment of the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the bevel gear 10 includes a gear portion 12. The gear portion 12 includes a hollow gear portion main body 14, teeth 16 formed on the radially outer side of the gear portion main body 14, and a cylindrical portion formed so as to protrude outward in the axial direction of the gear portion main body 14. 18. The gear portion 12 is formed by forging or casting.

  The bevel gear 10 includes a cylindrical shaft portion 20. One axial end portion of the shaft portion 20 is connected to the cylindrical portion 18 by friction welding. That is, by rotating the shaft portion 20 at a high speed around the axis while the one end portion in the axial direction of the shaft portion 20 is pressed against the cylindrical portion 18 with a predetermined pressure, one side in the axial direction of the shaft portion 20 is obtained. Friction heat is generated at the contact portion between the end portion and the cylindrical portion 18, and the one end portion in the axial direction of the shaft portion 20 and the cylindrical portion 18 are melted and cooled with each other by this heat. Connected.

  Here, the connecting portion between the cylindrical portion 18 of the gear portion 12 and the shaft portion 20 is at a position retracted from the movement locus line L of the gear cutter (not shown) when the teeth 16 of the gear portion 12 are processed. Is provided. That is, the shaft of the cylindrical portion 18 of the gear portion 12 is arranged so that the connection portion between the cylindrical portion 18 of the gear portion 12 and the shaft portion 20 is at a position retracted from the movement locus line L of the machining apparatus (not shown). The direction length is set to be relatively short.

  Next, the formation method of the bevel gear 10 of this embodiment is demonstrated.

  As shown in FIG. 2, the gear portion 12 and the shaft portion 20 are separately molded. Then, the teeth 16 of the gear unit 12 are processed by a processing device such as a gear cutter. At this time, since the cylindrical portion 18 is set to be relatively small in diameter and short, the cylindrical portion 18 protruding in the gear cutting surface direction does not interfere with the cutting cutter feed movement of the processing apparatus, and the gear portion 12 Since the shaft portion 20 is not integrally formed in advance, the shaft portion 20 does not affect the movement of the processing apparatus. After the processing of the teeth 16 is completed, the cylindrical portion 18 of the gear portion 12 and the axial one side end portion of the shaft portion 20 are abutted with each other with a predetermined pressure, and in this state, the shaft portion 20 is rotated around the axis at high speed. As shown in FIG. 1, when the shaft portion 20 is rotated at a high speed around the shaft center, the cylindrical portion 18 of the gear portion 12 and the one end portion in the axial direction of the shaft portion 20 are melted by frictional heat. Both are joined by being cooled.

  Next, a gear transmission device in which the bevel gear 10 of this embodiment is incorporated will be described.

  As shown in FIG. 3, a drive-side bevel gear (pinion gear) 26 is housed inside the housing 24 of the gear transmission 22. A cylindrical joint 28 is connected to the drive-side bevel gear 26, and one end of a drive shaft (not shown) is spline-fitted to the cylindrical joint 28. Thus, when the drive shaft rotates, the drive side bevel gear 26 also rotates. The bevel gear 10 of the present embodiment as a driven bevel gear (ring gear) is housed in the housing 24 of the gear transmission device 22 in a direction perpendicular to the drive bevel gear 26. The teeth 16 of the bevel gear 10 mesh with the teeth of the drive-side bevel gear 26. For example, a joint (not shown) fixed to a rear wheel hub (not shown) is connected to the bevel gear 10 by spline fitting. Accordingly, the driving side bevel gear 26 is rotated by the rotational driving force of the driving shaft, and the bevel gear 10 of the present embodiment as the driven side bevel gear is rotated by the rotation of the driving side bevel gear 26. This rotational driving force is transmitted to the rear wheel hub side. In this way, the bevel gear 10 has a function of transmitting rotational motion between two axes that intersect at right angles.

  Next, the operation of the bevel gear 10 of this embodiment will be described.

  As shown in FIGS. 1 and 2, the connecting portion between the cylindrical portion 18 of the gear portion 12 and the one end portion in the axial direction of the shaft portion 20 is the movement trajectory of the processing apparatus when processing the teeth 16 of the gear portion 12. Since it is provided at a position retracted from the line L, when gear teeth 12 of the gear portion 12 before the shaft portion 20 is connected are cut off, the cylindrical portion 18 and the shaft portion 20 of the gear portion 12 are Does not obstruct the movement of the processing equipment. As a result, the cylindrical portion 18 and the shaft portion 20 can be prevented from affecting the machining operation of the teeth 16 of the gear portion 12.

  In particular, since the cylindrical portion 18 of the gear portion 12 and the axial one side end portion of the shaft portion 20 are connected by friction welding at the connection site, the axial direction of the cylindrical portion 18 and the shaft portion 20 of the gear portion 12 is connected. The one side end can be firmly connected. Thereby, it is possible to prevent looseness and rattling after the assembly of the gear portion 12 and the shaft portion 20 regardless of the frequency of use of the bevel gear 10.

  Next, a bevel gear according to a second embodiment of the present invention will be described.

  As shown in FIGS. 4 and 5, the bevel gear 30 includes a gear portion 32. The gear portion 32 is formed so as to be recessed inward in the axial direction from the tooth surface side of the gear portion main body 34, a hollow gear portion main body 34, teeth 36 formed on the radially outer side of the gear portion main body 34. And a recess 38. In addition, a space 40 is formed on the radially outer side of the portion near the bottom of the recess 38. The gear portion 32 is formed by forging or casting.

  The bevel gear 30 includes a shaft portion 42. An enlarged diameter portion 44 is formed at one end portion of the shaft portion 42. The enlarged diameter portion 44 of the shaft portion 42 is inserted into the concave portion 38 and connected to the gear portion main body 34 by friction welding. That is, the shaft portion 42 is rotated at a high speed around the shaft center in a state where the diameter-expanded portion 44 of the shaft portion 42 is inserted into the recess 38 and pressed against the gear portion main body 34 with a predetermined pressure. Heat is generated at the connecting portion between the diameter portion 44 and the gear portion main body 34, and the expanded diameter portion 44 of the shaft portion 42 is melted and cooled by this heat, whereby the two are connected. Further, a part of the pressure contact beam 46 of the enlarged diameter portion 44 generated by the friction welding enters the space portion 40, whereby the space portion 40 is filled with the pressure contact beam 46.

  Next, the formation method of the bevel gear 30 of this embodiment is demonstrated.

  As shown in FIG. 5, the gear portion 32 and the shaft portion 42 are separately formed by forging, casting, cutting, or the like. At this time, the gear portion 32 is formed with a recess 38 and a space 40, respectively. Then, the teeth 36 of the gear portion 32 are processed by a processing device such as a gear cutter. At this time, since no projecting portion that interferes on the movement locus line L of the processing device is formed on the tooth surface side of the gear portion 32, there is no interference when the processing device moves during processing of the teeth 36. Since the shaft portion 42 is not formed integrally with the gear portion 32 in advance, the shaft portion 42 does not interfere with the movement of the machining apparatus. After completion of the processing of the teeth 36 of the gear portion 32, the concave portion 38 of the gear portion 32 and the diameter-expanded portion 44 of the shaft portion 42 are abutted with each other with a predetermined pressure, and in this state, the shaft portion 42 is rotated around the axis at high speed. When the shaft portion 42 is rotated at high speed around the shaft center, the diameter-expanded portion 44 of the shaft portion 42 is melted by frictional heat, and thereafter, the two are connected by being cooled. Here, when the enlarged diameter portion 44 of the shaft portion 42 is melted by frictional heat and then cooled, a pressure contact beam 46 is formed on the enlarged diameter portion 44 of the shaft portion 42 so as to protrude in the radial direction. A part of the pressure contact beam 46 enters the space 40. As a result, the interior of the space 40 is filled with the pressure contact beam 46, and the shaft portion 42 can be prevented from coming out due to the engagement of the return beam in the axial direction with the gear portion 32.

  Next, a gear transmission device in which the bevel gear 30 of this embodiment is incorporated will be described.

  As shown in FIG. 6, a drive-side bevel gear (pinion gear) 52 is accommodated in the housing 50 of the gear transmission 48. A cylindrical joint 54 is connected to the drive-side bevel gear 52, and one end portion of a drive shaft (not shown) is spline-fitted to the cylindrical joint 54. As a result, when the drive shaft rotates, the drive side bevel gear 52 also rotates. The bevel gear 30 of the present embodiment as a driven bevel gear (ring gear) is housed in the housing 50 of the gear transmission 48 in a direction substantially orthogonal to the drive bevel gear 52. The teeth 36 of the bevel gear 30 mesh with the teeth of the drive-side bevel gear 52. For example, a joint (not shown) fixed to a rear wheel hub (not shown) is connected to the bevel gear 30 by spline fitting. Accordingly, the driving side bevel gear 52 is rotated by the rotational driving force of the driving shaft, and the bevel gear 30 of the present embodiment as the driven side bevel gear is rotated by the rotation of the driving side bevel gear 52. This rotational driving force is transmitted to the rear wheel hub side. As described above, the bevel gear 30 has a function of transmitting rotational motion between two axes that intersect at substantially right angles.

  Next, the operation of the bevel gear 30 according to the second embodiment of the present invention will be described.

  As shown in FIGS. 4 and 5, the concave portion 38 of the gear portion 32 is formed at a position retracted from the movement trajectory line of the machining apparatus when machining the teeth 36, and is radially outward of the bottom portion of the concave portion 38 of the gear portion 32. A space portion 40 is formed, and a shaft portion 42 is inserted into the concave portion 38 of the gear portion 32 and connected by friction welding. Thereby, when the teeth 36 of the gear portion 32 are processed by a processing device or the like, the concave portion 38 does not hinder the movement of the processing device, and the shaft portion 42 is not connected to the gear portion 32 in advance. The shaft portion 42 does not interfere with the movement of the processing apparatus. Further, since the gear portion 32 and the shaft portion 42 are connected by friction welding, the gear portion 32 and the shaft portion 42 can be firmly connected, and the gear portion 32 and the gear portion 32 can be connected regardless of the frequency of use of the bevel gear 30. Assembling with the shaft portion 42 can be strengthened to prevent loosening. At the same time, since the press-contact beam 46 generated by the friction welding enters the space portion 40, the shaft portion 42 can be prevented from coming out of the gear portion 32. Further, by effectively using the pressure contact beam 46 to prevent the shaft portion 42 from being removed, the work of removing the pressure contact beam 46 is not required, and there is no need for a separate retaining means such as caulking, so that the manufacturing cost can be reduced. .

It is sectional drawing of the bevel gear concerning a 1st embodiment of the present invention. It is sectional drawing of the state which the gear part and shaft part which comprise the bevel gear concerning 1st Embodiment of this invention isolate | separated. It is sectional drawing of the gear transmission apparatus with which the bevel gear concerning 1st Embodiment of this invention was integrated. It is sectional drawing of the bevel gear concerning a 2nd embodiment of the present invention. It is sectional drawing of the state which the gear part and axial part which comprise the bevel gear concerning 2nd Embodiment of this invention isolate | separated. It is sectional drawing of the gear transmission apparatus with which the bevel gear concerning 2nd Embodiment of this invention was integrated.

Explanation of symbols

10 Bevel gear 12 Gear portion 16 Teeth 18 Tubular portion 20 Shaft portion 26 Drive side bevel gear (other gear)
30 Bevel gear 32 Gear portion 38 Concave portion 40 Space portion 42 Shaft portion 46 Pressure contact beam
52 Drive-side bevel gear (other gear)

Claims (5)

A bevel gear having a gear portion having teeth meshing with another gear and a cylindrical shaft portion connected to the cylindrical portion of the gear portion, and transmitting rotational motion between two intersecting axes,
A connecting portion between the cylindrical portion and the shaft portion of the gear portion is provided at a position retracted from a movement locus line of a processing apparatus when the teeth of the gear portion are processed. gear.   The bevel gear according to claim 1, wherein the cylindrical portion and the shaft portion of the gear portion are connected by friction welding at the connection portion. A bevel gear having a gear portion having teeth meshing with another gear and a cylindrical shaft portion inserted into and connected to a recess formed in the gear portion and transmitting rotational motion between two intersecting axes Because
The concave portion is formed at a position retracted from a movement trajectory line of a processing apparatus when processing the teeth, a space portion is formed on a radially outer side of the concave portion of the gear portion, and the concave portion of the gear portion is A bevel gear characterized in that a shaft portion is inserted and friction-welded and connected, and a beam generated by the friction-welding enters the space portion and prevents the shaft portion from coming off from the gear portion. A method for forming a bevel gear having a gear portion having teeth meshing with another gear, and a cylindrical shaft portion connected to the cylindrical portion of the gear portion, and transmitting rotational motion between two intersecting axes. There,
A connection part between the cylindrical part and the shaft part of the gear part is provided at a position retracted from the movement trajectory line of the processing device when the teeth of the gear part are processed, and the gear part of the gear part is provided at the connection part. A method of forming a bevel gear, wherein the tubular portion and the shaft portion are connected. A bevel gear having a gear portion having teeth meshing with another gear and a cylindrical shaft portion inserted into and connected to a recess formed in the gear portion, and transmitting rotational motion between two intersecting axes A forming method of
A first forming step in which the recess is formed at a position retracted from a movement trajectory line of a processing apparatus when processing the tooth;
A second forming step of forming a space portion on a radially outer side of the concave portion of the gear portion;
A connecting step in which the shaft portion is inserted into the concave portion of the gear portion and connected by friction welding;
A step of preventing the flash generated by the friction welding in the connecting step from entering the space portion and preventing the shaft portion from coming off from the gear portion, and
A method for forming a bevel gear.

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