EP1208927A2

EP1208927A2 - Rolling machine capable of forming different types of teeth simultaneously

Info

Publication number: EP1208927A2
Application number: EP00128748A
Authority: EP
Inventors: Jung-Il Lee; Eun-Taek Lee
Original assignee: Mando Corp
Current assignee: HL Mando Corp
Priority date: 2000-11-24
Filing date: 2000-12-30
Publication date: 2002-05-29
Also published as: US20020062671A1; KR100443883B1; JP2002160035A; EP1208927A3; KR20020040242A

Abstract

A rolling machine for performing a rolling of different types of teeth mounted on a shaft, is provided with a forming die (10) including a first section (11) and a second section (12) provided with a camming profiled circumferential surface of 360 degree. The circumferential surface is divided into a guide surface of a predetermined angle, a gradual forming surface of a predetermined angle, a finishing section surface of a predetermined angle, and a rotation stop section surface of a predetermined angle, which are angularly positioned in that order on the circumferential surface. The rolling machine is also provided with a power transmitting device for transmitting and disconnecting a driving force to the forming die (10) and a position detecting sensor for controlling a stop timing of the forming die.

Description

Field of the Invention

The present invention relates to a rolling machine; and, more particularly, to a rolling machine capable of forming different types of teeth which are coaxially formed with each other, at the same time.

Description of the Prior Art

In general, a rolling is widely used to form, e.g., a thread by interposing a thread blank or thread base metal between two or more sets of forming dies to be rolled therebetween. The metal plasticity of the thread blank enables the rolling. Since the rolling enables to product the thread having a higher accuracy and uniformity, manufacturing the normal thread is mainly achieved through the rolling.
There are many types of thread rolling apparatuses or rolling machines. The types of thread rolling apparatuses to be used is determined depending on the property of the component and an amount of production.
The thread rolling is largely divided into three kinds of methods.
First is to use flat dies or rack dies. A set of dies are arranged with the metal blank being supported therebetween and, then each of the dies is moved in an opposite direction to form the thread.
Secondly, a rotational method is performed in such a manner that rolling dies positioned inside segment dies mounted outmost are rotated, with the metal blank interposed between the rolling dies being formed into the thread. At the moment, the metal blank is moved at 1/2 speed of the rolling die.
Finally, a set of round dies is used. In one type of using the round dies, two round dies are rotated about only their rotational axes, respectively, with the metal blank being rotated between both round dies. In the other type of using the round dies, two round dies are rotated about their rotational axes, being rotated around the metal blank interposed therebetween.
The first and third methods have an advantage in mass production.
On the other hand, the shape and dimension of the metal blank for the rolling may easily influence the life time of the rolling die and the accuracy of the product. Accordingly, an inappropriate shape of the base material causes the breakage or higher wear of the rolling die.
In Fig. 1, there is shown a shaft for a starter motor which has been newly developed in recent days. The starter motor has a helical spline 1 having eight teeth and a spline 2 having four teeth which are mounted on one shaft. It is difficult to form the splines shaped like this, i.e., the two splines having different tooth profiles by using a conventional rolling method.
That is, although one method where two types of splines are simultaneously rolled was conventionally tried, the shape of one of the splines after the rolling became useless since the two require different rolling environments and different circumferential speeds.
On the other hand, synchronizing the rotation of the spline blank with the rotation of the rolling dies was applied. However, the tooth of the rolling dies deviates from the tooth of the spline blank during the rolling, failing to obtain a product with a proper dimension.

Summary of the Invention

It is, therefore, a primary object of the invention to provide a rolling machine capable of performing a rolling of different types of teeth at the same time.
In order to achieve the object, the present invention provides a rolling machine for performing a rolling of different types of teeth mounted on a shaft, the machine comprising: a forming die including a first section and a second section provided with a camming profiled circumferential surface of 360 degree, the circumferential surface being divided into a guide surface of a predetermined angle, a gradual forming surface of a predetermined angle, a finishing section surface of a predetermined angle, and a rotation stop section surface of a predetermined angle, which are angularly positioned in that order on the circumferential surface; a power transmitting device for transmitting and disconnecting a driving force to the forming die; and a position detecting sensor for controlling a stop timing of the forming die.

Brief Description of the Drawings

The above and other objects and features of the instant invention will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which:
Fig. 1 illustrates a perspective view of a shaft of a starter motor;
Fig. 2 shows a schematic perspective view of forming dies in accordance with the present invention;
Fig. 3 depicts a frontal view of a second rolling section in accordance with the present invention; and
Fig. 4 present a scheme of an inventive rolling machine capable of forming different types of teeth simultaneously.

Detailed Description of the Preferred Embodiments

A preferred embodiment of an inventive rolling machine is described with reference to accompanying drawings.
Fig. 2 shows a schematic perspective view of forming dies in accordance with the present invention, Fig. 3 depicts a frontal view of a second rolling section in accordance with the present invention, and Fig. 4 present a scheme of the inventive rolling machine capable of forming different types of teeth simultaneously.
As shown, a preferred embodiment of the present invention examples a shaft of a starter motor(see Fig. 1) which has a helical spline 1 having eight teeth and a spline 2 having four teeth which are mounted on one shaft.
The inventive rolling machine is a roller type. As shown in Fig. 2, the roller type rolling machine is provided with two forming dies 10 whose rotational shafts are parallel with each other. One forming die 10 is movable, while position of the other is fixed, so that the forming dies 10 and a shaft blank, i.e., a starter motor shaft spline blank rotate together, depressing against one another.
In the roller type rolling machine, since the workpiece, i.e., the shaft blank has a different circumferential length between at a start point of the rolling and at an end point of the rolling, it has to be rolled simultaneously.
As shown, each of the forming dies 10 has a first section 11 for forming the helical spline having eight teeth, and a second section 12 for forming the spline having four teeth, which are mounted on a same shaft.
The first section 11 and the second section 12 has a tooth profile having a same pitch as that of a tooth of the a starter motor shaft to be produced. The tooth of the first section 11 and the second section 12 is offset to the tooth of the starter motor shaft to be produced. That is, a crest of the tooth of the sections 11 and 12 corresponds to recess of the tooth of the starter motor shaft to be produced.
On the other hand, since the first section 11 and the second section 12 require rolling environments different from each other and have different circumferential speeds, the start point of the rolling has to be coincided every rotation.
For this, the forming dies 10 has a camming profile in its cross-section instead of a real circle. A circumferential surface of 360 degree of the forming dies 10 is divided into a guide surface 13 of a predetermined angle, a gradual forming surface 14 of a predetermined angle, a finishing section surface 15 of a predetermined angle, and a rotation stop section surface 16 of a predetermined angle, which are angularly positioned in that order.
In accordance with the present invention, the guide surface 13 has a same curvature so as to serve to guide at the beginning of the rolling. accordingly, an amount of cutting advancement of the forming dies 10 becomes very small. It is preferable that the guide surface 13 range from 80 degree to 100 degree in the circumferential surface of 360 degree.
In accordance with the present invention, the gradual forming surface 14 has a crest of the tooth of the forming dies which has a higher height along the circumference from an initial point toward a completion point, to progressively form in the shaft blank the helical spline having eight teeth and the spline having four teeth. It is preferable that the gradual forming surface 14 range from 125 degree to 145 degree in the circumferential surface of 360 degree. Further, the gradual forming surface 14 is eccentrically formed to have a radius from a central axis which becomes larger in 0.02mm increment from tooth to tooth, so that it progressively forms the tooth of the spline.
The finishing section surface 15 is contiguous to the gradual forming surface 14 and has a range from 80 degree to 100 degree in the circumferential surface of 360 degree. The tooth profile of the finishing section surface 15 is same as that of the completion point of the gradual forming surface 14. On the other hand, the rotation stop section surface 16 is formed between the remainder angle about 35 to 55 degree in the circumferential surface of 360 degree. Although the rotation stop section surface 16 does not have a tooth for performing the rolling of the tooth, it functions to correct different rolling environments and the different circumferential speeds. That is, when an initial point of the rotation stop section surface 16 arrives at the workpiece, the driving force is disconnected from the forming dies 10 and then the rotation of the forming dies 10 is temporarily stopped. The driving force is supplied to rotate the forming dies 10 at the beginning point of the guide surface 13.
For this, the inventive rolling machine is provided with a power transmitting device 20 for controlling the transmission of the driving force to the forming dies 10, and a position detecting sensor 30 for controlling the stop timing of the forming dies 10.
In accordance with the present invention, the power transmitting device 20 includes a driving motor 21 for generating the driving force, a driving shaft 24 receiving the driving force from the driving motor 21, a clutch 23 for connecting and disconnecting the driving force from the driving shaft 24, and a brake 23 for stopping the rotation of the driving shaft 24.
The position detecting sensor 30 includes a driving force disconnecting sensor 31 positioned at the initial point of the rotation stop section surface 16, and a stop check sensor 32 positioned at a center portion of the rotation stop section surface 16. That is, the driving force disconnecting sensor 31 actuates the clutch 20 to disconnect the driving force, when the initial point of the rotations stop section surface 16 meets the shaft blank, i.e., the workpiece, during the rotation of the forming dies 10. Further, the stop check sensor 32 actuates the brake 23 to stop the forming dies 10 being rotated due to the inertia after the disconnection of the driving force.
Although the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims

A rolling machine for performing a rolling of different types of teeth mounted on a shaft, the machine comprising:

a forming die including a first section and a second section provided with a camming profiled circumferential surface of 360 degree, the circumferential surface being divided into a guide surface of a predetermined angle, a gradual forming surface of a predetermined angle, a finishing section surface of a predetermined angle, and a rotation stop section surface of a predetermined angle, which are angularly positioned in that order on the circumferential surface;

a power transmitting device for transmitting and disconnecting a driving force to the forming die; and

a position detecting sensor for controlling a stop timing of the forming die.
The rolling machine of claims 1, wherein the guide surface has a same curvature and ranges from 80 degree to 100 degree in the circumferential surface of 360 degree.
The rolling machine of claims 1, wherein the gradual forming surface has a crest of the tooth which has its height higher along the circumference from an initial point toward a completion point.
The rolling machine of claims 1, wherein the gradual forming surface ranges from 125 degree to 145 degree in the circumferential surface of 360 degree.
The rolling machine of claims 1, wherein the gradual forming surface is eccentrically formed to have a radius from a central axis which becomes larger in 0.02mm increment from tooth to tooth.
The rolling machine of claims 1, wherein the tooth profile of the finishing section surface is same as that of a completion point of the gradual forming surface.
The rolling machine of claims 1, wherein the finishing section surface has a range from 80 degree to 100 degree in the circumferential surface of 360 degree.
The rolling machine of claims 1, wherein the rotation stop section surface is formed between an angular range about 35 to 55 degree in the circumferential surface of 360 degree.
The rolling machine of claims 1, wherein the rotation stop section surface does not have a tooth for performing the rolling of the tooth.
The rolling machine of claims 1, wherein the power transmitting device includes a driving motor for generating the driving force, a driving shaft receiving the driving force from the driving motor, a clutch for connecting and disconnecting the driving force from the driving shaft, and a brake for stopping the rotation of the driving shaft.
The rolling machine of claims 1, wherein the position detecting sensor includes a driving force disconnecting sensor positioned at the initial point of the rotation stop section surface, and a stop check sensor positioned at a center portion of the rotation stop section surface.