Method and device for precision machining of toothed and hardened work wheels

Abstract

A method for machining toothed and hardened work wheels, includes: mounting a work wheel that is hardened and pre-toothed with an allowance onto a workpiece spindle; removing at least 50% of the allowance by means of gear skiving with a skiving wheel that is rotatably driven by a tool spindle; precision-machining the work wheel in unchanged tension by means of a honing wheel. The forward movement occurs during gear skiving in the extension direction of the toothing. The delivery of the workpiece that is moved in an oscillating manner in the extension direction of the toothing occurs during honing in the radial direction. The skiving wheel and the honing wheel are driven by a common tool spindle. A device for carrying out the method includes a workpiece spindle, which is driven to rotate, and a tool spindle, which carries a combination tool having a skiving wheel and a honing wheel.

Claims

1. A method for machining toothed and hardened work wheels, comprising the following steps: preparing a work wheel in an unhardened state with teeth having an allowance; hardening the work wheel to a surface hardness of at least 45 HRC, the hardening causing a hardness distortion error that is less than the allowance; chucking the work wheel on a workpiece spindle; removing at least 50% of the allowance by gear skiving with a skiving wheel, the skiving wheel being driven to rotate by a tool spindle; and precision machining the work wheel with no change in chucking using a honing wheel; wherein the skiving wheel and the honing wheel are driven by the same tool spindle, wherein a forward movement in gear skiving takes place in the direction of extent of the toothing, wherein the forward movement involves no movement in a radial direction perpendicular to the direction of extent of the toothing; and wherein a feed motion of the work wheel with an oscillating motion in the direction of extent of the toothing is in the radial direction during the precision machining step.

2. The method according to claim 1, wherein the skiving wheel is a ceramic or hard metal skiving wheel.

3. The method according to claim 1, wherein the honing wheel is a ceramically bonded, dressable tool.

4. The method according to claim 3, wherein the honing wheel is a CBN tool.

5. The method according to claim 1, wherein the gear skiving machining takes place in a single forward movement for each tooth in the direction of extent of the toothing.

6. The method according to claim 1, wherein the honing wheel is carried by the tool spindle and is dressed using a dressing tool, which is associated with the device and is carried by the workpiece spindle.

7. A method for machining work wheels, comprising: providing a work wheel that has been pre-toothed with teeth having an allowance; hardening the work wheel to a surface hardness of at least 45 HRC, the hardening step causing a hardness distortion error that is less than the allowance; chucking the work wheel on a workpiece spindle; gear skiving the work wheel using a skiving wheel to remove at least 50% of the allowance therefrom, the gear skiving involving rotationally driving the skiving wheel with a tool spindle; during the gear skiving step, moving the skiving wheel in a direction of an axis of the work wheel, wherein the moving step involves no movement in a radial direction perpendicular to the axis of the work wheel; without rechucking the work wheel after the gear skiving step, precision machining the work wheel using a honing wheel, the precision machining involving rotationally driving the honing wheel with the same tool spindle that rotationally drives the skiving wheel; and during the precision machining step, moving the work wheel in an oscillating motion in the radial direction perpendicular to the axis of the work wheel.

8. The method according to claim 7, wherein the gear skiving step takes place for each tooth during a single movement of the skiving wheel in the direction of the axis of the work wheel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) One exemplary embodiment of the invention explained below on the basis of the accompanying drawings, in which:

(2) FIG. 1 shows schematically a workpiece spindle 4 with a chuck 3, which chucks a workpiece 1, and a tool spindle 7, which carries a combination tool comprising a skiving wheel 5 and a honing wheel 6;

(3) FIG. 2 shows a diagram according to FIG. 1 in skiving machining; and

(4) FIG. 3 shows a diagram according to FIG. 1 in honing machining.

DETAILED DESCRIPTION

(5) The drawings show only details of a machine tool according to the invention. The machine tool according to the invention has a machine bed (not shown in the drawings) and a housing. Inside the housing there is a workpiece spindle 4, which is driven to rotate by an electric motor. In addition, a tool spindle 7 is also provided, with a skiving tool 5 and a honing tool 6 mounted thereon. The skiving tool 5 is preferably a hard metal skiving wheel, which is arranged coaxially with a honing wheel 6, preferably made of CBN. The tool spindle 7 is driven by an electric motor. The electric motors are synchronized with one another in such a way that the workpiece spindle 4 and the tool spindle 7 can be driven to rotate in synchronization. In addition, drives, which permit an adjustment and a forward movement, are also provided. All the drives are driven by an electronic control unit. The electronic control unit has a program memory for storage of a machining program. The machining program includes a machining method.

(6) A work wheel 1 is prepared to carry it out the machining method. The work wheel 1 is first provided with teeth in an unhardened state. The teeth have an allowance of, for example, four to eight hundredths of a millimeter, but the allowance may also amount to only six hundredths of a millimeter. The allowance is sufficient to correct any hardness distortion and defects in shape and/or concentricity. Next, the work wheel, which has been pre-toothed in this way is hardened. This results in hardness distortion.

(7) In a first method step, the hardened work wheel, after being pre-toothed with an allowance, is chucked on the tool spindle 4. In a second method step, most of the allowance is removed by gear skiving using the skiving wheel 5 that is driven to rotate by the tool spindle 7. The machining takes place to a certain extent into the solid material, and in a step in which all the tooth flanks of the toothing 2 of the work wheel 1 are being machined. The gear skiving machining takes place with a forward movement V.sub.S in the direction of extent of the teeth. The workpiece axis and the tool axis, i.e., the axes of rotation of the tool spindle 7 and the workpiece spindle 4, form an axle-crossing angle. There is preferably no shift in forward movement in the radial direction during gear skiving. The skiving wheel 1 may be manufactured from hard metal, ceramic or some other suitable hard material.

(8) In a third method step, which is carried out without re-chucking of the work wheel 1, precision machining of the hard machined toothing 2 is carried out by means of gear skiving. To do so, the honing wheel 6 is brought into a machining position. During the honing machining, the work wheel 1 oscillates in the direction of extent of the teeth. The feed motion V.sub.H here is in the radial direction.

(9) The preceding discussion serves to illustrate the inventions, which are covered on the whole by the present patent application and which reflect the prior art at least through the following combinations of features, even independently, namely:

(10) A method for machining toothed and hardened work wheels 1, comprising the following steps: chucking the work wheel 1, which has been pre-toothed with an allowance and hardened, on a workpiece spindle 4; removing at least 50% of the allowance by gear skiving with a skiving wheel 5 that is driven to rotate by a tool spindle 7; and precision machining of the work wheel 1 by means of a honing wheel 6 with no change in chucking.

(11) A method, which is characterized in that the forward movement V.sub.S in gear skiving takes place in the direction of extent of the toothing 2.

(12) A method, which is characterized in that the feed motion V.sub.H of the work wheel 1, which is moved by oscillation in the direction of extent of the toothing 2, is carried out in honing in the radial direction.

(13) A method, which is characterized in that the skiving wheel 5 and the honing wheel 6 are both driven by the same tool spindle 7.

(14) A method, which is characterized in that the skiving wheel 5 is a ceramic skiving wheel or a hard metal skiving wheel.

(15) A method, which is characterized in that the honing wheel 6 is a ceramically bonded, dressable tool, in particular a CBN tool.

(16) A method, which is characterized in that the gear skiving machining takes place in a single step.

(17) A method, which is characterized in that the honing wheel 6, which is mounted on the tool spindle 7, is dressed by means of a dressing tool assigned to the device and mounted on the workpiece spindle 4 in particular.

(18) A device, which is characterized in that the control unit is equipped so that at least 50% of the allowance can be removed by gear skiving with a skiving wheel driven to rotation by the tool spindle 7 after a work wheel 1, which has been pre-toothed with an allowance and hardened, has been chucked on the workpiece spindle 4, and then the work wheel 1 while in the same chucking is precision machined by means of a honing wheel 6 driven to rotate by one of the tool spindles.

(19) A device, which is characterized in that the skiving wheel 5 and a honing wheel 6 sit on the same tool spindle 7.

(20) A device, which is characterized by a dressing tool with which the honing wheel 6 that is mounted on the tool spindle 7 can be dressed.

(21) A tool, which is characterized in that a skiving wheel 5 and a honing wheel 6 are combined coaxially and axially behind one another to form a combination tool, which can be driven to rotate by the same tool spindle 7.

(22) A method, a device or a tool, which are characterized in that the skiving wheel 5 is a hard metal skiving wheel 5.

(23) A method, a device or a tool, which are characterized by a ceramically bonded honing wheel 6, in particular one that can be dressed and is a CBN tool in particular.

(24) All the features disclosed here (either separately or in any combination with one another) are essential to the invention. The full content of the disclosure of the respective/attached priority documents (photocopy of the previous patent application) is herewith included in the disclosure of the present patent application, also for the purpose of including features of these documents in the claims of the present patent application. The dependent claims with their features characterize independent refinements of the prior art according to the invention, in particular to be able to make divisional applications on the basis of these claims.