Lathe Slide Feed Control for Precise Electronic End Positioning

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Solution Overview

Problem

Conventional lathes face accuracy issues due to elastic behavior of mechanical components and non-precise adjustability in mechanical fixed stops, leading to imprecise end position values during workpiece processing, especially when using mechanical clutches for feed control.

Innovation Solution

Implementing separate electronic drives for the main spindle and tension spindle, allowing precise control of workpiece-dependent travel and end positions through electronic control, eliminating the need for mechanical clutches and enhancing the precision of end position values by using a delay function for gentle spindle engagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a mechanical stop and mechanical clutch are used to limit slide movements, then the structure is simple and easy to operate, but the end position accuracy deteriorates due to elastic behavior and overshooting

Engineering Contradiction:
Improveease of operationVSAvoidend position accuracy
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical clutch and stop-based feed control system with an electronic control system that directly controls the drive motor. The electronic control unit receives stop position coordinates, calculates the distance to the stop, and controls the feed motor to decelerate and stop precisely at the target position, eliminating mechanical overshooting and improving end position accuracy while maintaining ease of operation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback mechanism where the control unit continuously monitors the slide's position during feeding, compares it with the target stop position, and dynamically adjusts the feed motor's speed and torque. This closed-loop control enables precise stopping at the predetermined position without mechanical contact, resolving the contradiction between simple mechanical operation and precise positioning.

Inventive Principle:
Principle #23Feedback

2Device complexity

If a mechanical clutch is used to interrupt feed, then the structure is simple, but the end position accuracy deteriorates due to imprecise clutch release torque and elastic behavior

Engineering Contradiction:
Improvedevice complexityVSAvoidend position accuracy
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent eliminates the mechanical clutch entirely by using an electronic control system that directly controls the feed motor's torque and speed. The control unit calculates the precise deceleration profile based on the distance to the stop position and controls the motor to stop exactly at the target, replacing complex mechanical torque adjustment mechanisms with electronic control and improving positioning accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The control unit performs preliminary calculations of the deceleration profile and stopping point before the slide reaches the stop position. By pre-calculating the required deceleration based on current position and target position, the system can smoothly reduce speed and stop precisely at the predetermined location, avoiding the need for mechanical clutch engagement and improving accuracy.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If manual operation is used to achieve precise end positions, then positioning accuracy improves, but productivity deteriorates due to continuous monitoring requirement

Engineering Contradiction:
Improveend position accuracyVSAvoidproductivity
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent implements an automatic positioning system where the control unit autonomously monitors the slide's position during feeding, calculates the distance to the stop, and controls the feed motor to stop precisely at the target position without operator intervention. This automation maintains high positioning accuracy while eliminating the need for continuous manual monitoring, thereby improving productivity.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system continuously feedbacks the slide's position to the control unit, which automatically adjusts the feed motor's speed and torque to ensure precise stopping at the predetermined position. This automated feedback control replaces manual positioning operations, maintaining accuracy while freeing the operator for other tasks and improving overall productivity.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP2431114B9Rotating machine with a guide and feed rod and an electronic control for the longitudinal and/or cross slide
Publication Date: 2022.08.31 WEILER WERKZEUGMASCH
  • EP2431114B9 patent drawingFigure 1
  • EP2431114B9 patent drawingFigure 2

AI summary

The rotating lathe (D) has a main spindle (5) for insertion of a work piece, where a carriage (2), particularly a longitudinal carriage, is displaceable on an axle (A1) which is the Z-axis. Another axle (A2) is provided which is the X-axis. A main spindle drive and a drag spindle drive are also provided.