Method for manufacturing a rack for a steering gear
By varying the feed speed of the cutting machine during the production of toothed racks for motor vehicle steering systems, the method addresses the issue of acoustic anomalies, achieving reduced noise generation and potentially eliminating the need for additional grinding processes.
Patent Information
- Application Number
- DE102023210723
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-10-30
- Publication Date
- 2025-04-30
AI Technical Summary
Racks in rack and pinion gear units for motor vehicle steering systems often produce acoustic anomalies, such as singing noises, due to material waviness, which can be costly to address through additional grinding processes.
The method involves varying the feed speed of the cutting or forming machine during the production of the toothed rack, using non-constant feed patterns such as sawtooth-shaped, block-wise, or sinusoidal variations, to counteract the generation of oscillations and resonances.
This approach effectively minimizes noise generation by irregularly arranging machining tracks, potentially eliminating the need for subsequent grinding processes, thereby reducing costs and improving acoustic performance.
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Abstract
Description
[0001] The present invention relates to a method for producing a rack for a rack and pinion gear for the steering of a motor vehicle. State of the art
[0002] Racks are used in rack and pinion drives of automotive steering systems to convert the rotation of a pinion into a translational movement of the rack, which then pivots the vehicle wheels via the tie rods. Such racks have a toothed section and a shaft section.
[0003] The rack raw material is typically produced through a machining process followed by a pressure forming process, such as skiving and / or pressure polishing. A constant feed rate is set on the machine, with either the tool or the workpiece moving. During the process, chips or material indentations form in a regular sequence.
[0004] The disadvantage of such racks is that the support at the shaft area causes acoustic abnormalities, which are usually perceived as a whistling noise. These abnormalities are attributed to the waviness of the material. While it is possible to subject the material to a further grinding process, this entails additional costs.
[0005] It is therefore the object of the invention to provide a method for producing a rack which prevents the formation of waviness so that as little noise as possible is generated.
[0006] This object is achieved by the teaching of claim 1 in that during the manufacture of the rack the feed rate of the cutting or forming machine is not constant but is deliberately varied.
[0007] The feed rate can be varied in different ways, for example, sawtooth, block, or sinusoidal. Combinations of these are also possible.
[0008] One idea of the invention is to vary the feed rate of the skiving process and / or the pressure polishing process of the rack raw material, for example, by superimposing one or more sine functions that alternately accelerate or decelerate the skiving or rolling process. This dissolves the original surface structure with regularly occurring spiral machining marks from the skiving or rolling tools.
[0009] This advantageously counteracts the generation of vibrations and noise, as the irregular arrangement of the machining marks created by the invention counteracts the development of resonances. Ideally, a subsequent grinding process for the rack is no longer required.
[0010] An embodiment is described using the figures. They show: Fig. 1 a rack for a rack and pinion gear Fig. 2 a sawtooth-shaped variation of the feed Fig. 3 a sinusoidal variation of the feed
[0011] In the Fig. 1 is a rack for a rack and pinion gear, comprising a toothed section 1 and a shaft section 2. The shaft section 2 must be supported in the rack and pinion steering system. To avoid acoustic problems, the shaft section 2 is manufactured using the method according to the invention.
[0012] In the Fig. Figure 2 shows a sawtooth-shaped variation of the feed rate. Five waves are shown over the entire travel.
[0013] In the Fig. A corresponding sinusoidal curve is shown in Figure 3.
Claims
[1] Method for producing a rack for a rack and pinion gear, wherein the rack is produced by machining and pressure forming with a machine; wherein the rack has a toothed region (1) and a shaft region (2); wherein the rack or a tool is moved translationally on the machine by a feed; characterized by , that when manufacturing the shaft area, at least during machining, the feed rate over the machining path is not constant and is deliberately varied. [2] Method according to claim 1, characterized by that the feed rate is varied in a sawtooth shape. [3] Method according to claim 1, characterized by that the feed rate is varied block by block. [4] Method according to claim 1, characterized by that the feed rate is varied according to a given, continuously differentiable function. [5] Method according to one of the preceding claims, characterized by that the rack is manufactured by a skiving process and / or pressure polishing process.
Citation Information
Patent Citations
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process for machining gears with variable speed
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