Camshaft Clamping Device for Precision Machining
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Solution Overview
Problem
The manufacturing of assembled camshafts for internal combustion engines faces challenges in achieving precise running surface geometries without significant additional effort, as deformations during the shrinking process of cam disks require post-processing to ensure proper functionality and prevent edge wear.
Innovation Solution
A method and device involving a clamping device that applies a defined clamping force to the cam disk before shrinking, mimicking the stress state after shrinking, allowing for precise machining of the running surface without subsequent post-processing, using a hydraulically expandable clamping tube that exerts a clamping force comparable to the deformation state during the shrinking process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cam disk is shrunk onto the shaft by cooling the shaft and heating the cam disk, then the cam disk is firmly fixed on the shaft, but deformations occur on the running surface requiring post-processing
Solution Approach 1:
The invention applies preliminary clamping to the cam disk before shrinking, where a clamping force is exerted on the wall region defining the cam disk recess to predetermined extent correspond to the stress state after shrinking. The running surface is machined in this clamped state, so that after shrinking the desired running surface geometry is already present without requiring post-processing
Solution Approach 2:
The clamping device pre-applies stress to the cam disk that counteracts the deformations that will occur during shrinking. By machining the running surface while the disk is clamped in this predetermined stress state, the subsequent shrinking process produces minimal additional deformation, preventing edge wear and eliminating the need for corrective post-processing
2Manufacturing precision
If post-processing is performed to correct deformations after shrinking, then precise running surface geometry is achieved, but production time and cost increase
Solution Approach 1:
The running surface is machined to final precision before the shrinking process, while the cam disk is in a clamped state that predetermined extent corresponds to the stress state after shrinking. This preliminary machining in the correct stress state eliminates the need for post-processing operations, thereby maintaining high manufacturing precision while significantly improving production efficiency
3Weight of moving object
If thin-walled components are used to reduce weight, then cost-effectiveness and weight are improved, but deformations during shrinking increase requiring additional post-processing
Solution Approach 1:
The clamping device applies a predetermined clamping force to thin-walled cam disks before machining, simulating the stress state that will occur during shrinking. This allows the running surface to be finished to precise geometry while the disk is under controlled stress, compensating for the higher deformability of thin-walled components and eliminating post-processing needs
Solution Approach 2:
The invention changes the stress state parameters of the thin-walled cam disk during machining by applying a predetermined clamping force that corresponds to the expected stress after shrinking. This parameter control allows precise machining of thin-walled components without the deformations that would otherwise require post-processing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach eliminates the need for post-processing by ensuring the running surface is accurately finished before shrinking, maintaining the desired geometry and quality, thus reducing production costs and effort while preventing edge wear during operation.
Implementation Method 1
this clamping tube is expanded, in particular elastically expanded, in such a way that when this area is expanded by applying a corresponding force and directed outwards in the direction of the cam disk, a defined clamping force is exerted on the recess wall region
Implementation Method 2
The force is applied hydraulically via a hydraulic device connected to the clamping tube
Implementation Method 3
for example by cooling the shaft and heating the cam disk
Data Source
Figure 1~3
Figure 4~5
AI summary
The invention relates to a method for manufacturing a built camshaft (1), in particular for valve-controlled internal combustion engines, in which at least one cam disc (3) with base circle area and cam area on the running surface is machined and has a cam disc recess (3a), in particular a bore, by means of which the cam disc (3) is shrunk onto a corresponding shaft (2) having a defined dimensional overlap, in particular by cooling the shaft (2) and heating the cam disc (3).According to the invention, the at least one cam disk (3) is clamped by means of a clamping device (4; 8) before being shrunk onto the shaft (2) such that a clamping force acts on the recess wall region (3b) of the cam disk (3) defining the recess (3a), which corresponds to a predetermined degree to the stress and/or deformation state of the recess wall region (3b) after the shrinking process of the cam disk (3) onto the corresponding shaft (2), and that the machining of the running surface of the at least one cam disk (3) is carried out in the clamped state by means of the clamping device (4; 8). The invention further relates to a device.