JP2007111792A - Gear processing method - Google Patents

Abstract

To improve gear machining accuracy.
A work gear is a worm wheel of a worm gear mechanism. The work gear 1 has already been roughly processed. The tooth surface of the work gear 1 is finished by changing the axis between the tool 11 and the work gear 1. At this time, the tooth tip diameter portion 12 of the tool 11 does not process the tooth bottom 2 of the work gear 1, or the tooth root diameter portion 13 of the tool 11 does not process the tooth tip 3 of the work gear 1. Instead, the tooth tip diameter portion 12 of the tool 11 does not process the tooth bottom 2 of the work gear 1, and the tooth root diameter portion 13 of the tool 11 processes the tooth tip 3 of the work gear 1. do not do.
[Selection] Figure 2

Description

  The present invention preferably relates to a gear machining method capable of finishing a worm wheel of a worm gear mechanism of an electric power steering device as a work gear to improve gear machining accuracy.

  In a steering system of an automobile, a so-called power steering device that performs steering assist using an external power source is widely adopted. Conventionally, vane type hydraulic pumps have been used as power sources for power steering devices, and many of these hydraulic pumps are driven by an engine. However, this type of power steering device has a large engine drive loss due to the constant drive of the hydraulic pump (several horsepower to about 10 horsepower at the maximum load), so it can be used in light vehicles with small displacement. It was difficult, and it was unavoidable that the fuel consumption of a car with a relatively large displacement was reduced to a level that could not be ignored.

  In order to solve these problems, an electric power steering device (Electric Power Steering, hereinafter referred to as EPS) using an electric motor as a power source has attracted attention in recent years. The EPS uses an in-vehicle battery as a power source for the electric motor, so there is no direct engine drive loss, and since the electric motor is started only at the steering assist time, a decrease in driving fuel consumption is suppressed, and electronic control is performed. It has the feature that it can be done very easily.

  In EPS, an auxiliary steering torque is generated from an electric motor in response to a steering torque applied to a steering wheel, and is decelerated by a power transmission mechanism (reduction gear) and transmitted to an output shaft of the steering mechanism. Yes.

  In EPS using a worm gear mechanism as the power transmission mechanism (reduction gear), a worm wheel meshes with a worm on the drive shaft side of the electric motor, and this worm wheel is connected to an output shaft (for example, a pinion) of a steering mechanism. Shaft, column shaft).

By the way, when finishing the gear tooth surface of the worm wheel of the worm gear mechanism, the finishing process of the gear subjected to the hob cutting is performed with a tool to which diamond abrasive grains or the like are attached. In this case, gear tooth surface machining is performed with the same tool shape as the hob. For this reason, both the tooth tip and the tooth bottom of the tool machine the tooth bottom and the tooth tip of the work gear.
JP-A-8-175403

  However, if a tool tooth bottom or cutting edge is added to the contact between the tool and the cutting gear, in order to improve the machining accuracy, in addition to the gear tooth surface machining part of the tool that is necessary as the machining gear accuracy, Unless the accuracy of the tooth tip diameter portion is increased, the state of the tooth surface contact depends on the contact other than the tooth surface, and therefore the accuracy of the work gear cannot be increased.

  In particular, if the worm wheel is combined with a worm wheel and the tooth surface is processed with a tool having the same shape as the worm wheel, the tool shaft diameter will be smaller than the hob diameter used for normal worm wheel processing, resulting in lower tool rigidity and further processing. It will reduce accuracy.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a gear machining method capable of improving the gear machining accuracy.

In order to achieve the above object, a gear machining method according to the present invention is a gear machining method in which a gear tooth surface of a already machined gear is finished with a tool.
The tooth tip diameter portion of the tool does not process the tooth bottom of the work gear, or the tooth bottom diameter portion of the tool does not process the tooth tip of the work gear.

Further, the gear machining method according to the present invention is a gear machining method in which a gear tooth surface of a gear to be machined that has already been roughly machined is finished with a tool.
The tooth tip diameter portion of the tool does not process the tooth bottom of the work gear, and the tooth bottom diameter portion of the tool does not process the tooth tip of the work gear.

  Preferably, diamond abrasive grains are attached to the tool.

  Preferably, the work gear is a worm wheel of a worm gear mechanism.

  According to the present invention, the tooth tip diameter portion of the tool does not process the tooth bottom of the work gear and / or the tool tooth bottom diameter portion does not process the tooth tip of the work gear. The machining accuracy can be improved.

  Hereinafter, a gear machining method according to an embodiment of the present invention will be described with reference to the drawings.

  1A and 1B show a gear machining method according to an embodiment of the present invention. FIG. 1A is a schematic diagram of a tool, and FIG. 1B is a schematic diagram of a worm wheel as a work gear.

  FIG. 2 shows a gear machining method according to the embodiment of the present invention, and is a schematic diagram of a machining state in which a worm wheel as a work gear is machined by a tool.

  The work gear 1 is a worm wheel of a worm gear mechanism. The work gear 1 has already been roughly processed. Abrasive grains such as diamond are attached to the tool 11.

  As shown in FIG. 2, the tooth surface of the work gear 1 is finished by changing the axis between the tool 11 and the work gear 1.

  At this time, the tooth tip diameter portion 12 of the tool 11 does not process the tooth bottom 2 of the work gear 1, or the tooth root diameter portion 13 of the tool 11 does not process the tooth tip 3 of the work gear 1.

  Instead, the tooth tip diameter portion 12 of the tool 11 does not process the tooth bottom 2 of the work gear 1, and the tooth root diameter portion 13 of the tool 11 processes the tooth tip 3 of the work gear 1. do not do.

  Therefore, the machining accuracy of the work gear 1 that is a worm wheel of the worm gear mechanism can be improved.

  In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible.

The gear processing method which concerns on embodiment of this invention is shown, (a) is a schematic diagram of a tool, (b) is a schematic diagram of the worm wheel as a to-be-cut gear. It is a schematic diagram of the processing state which shows the processing method of the gear which concerns on embodiment of this invention, and processes the worm wheel as a to-be-cut gear with a tool.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Work gear 2 Ground bottom of work gear 3 Tooth tip of work gear 11 Tool 12 Tool tip diameter part 13 Tool tooth root diameter part

Claims (4)

In a gear machining method in which a gear tooth surface of a already machined gear is finished with a tool,
The tooth tip diameter portion of the tool does not machine the tooth bottom of the work gear, or the tooth bottom diameter portion of the tool does not work the tooth tip of the work gear. Method. In a gear machining method in which a gear tooth surface of a already machined gear is finished with a tool,
The gear tip characterized in that the tooth tip diameter portion of the tool does not process the tooth bottom of the work gear, and the tooth bottom diameter portion of the tool does not process the tooth tip of the work gear. Method.   The gear machining method according to claim 1, wherein diamond abrasive grains are attached to the tool.   The gear machining method according to any one of claims 1 to 3, wherein the work gear is a worm wheel of a worm gear mechanism.

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