Ball Screw Tailstock Pressure Control Without Hydraulics

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Solution Overview

Problem

Conventional hydraulic cylinders require large spaces and complex operations for controlling the movement and pressure application in tail stock mechanisms, making them unsuitable for speedy control and efficient use of space.

Innovation Solution

A tail stock moving mechanism using a ball screw with a drive motor and brake system, where the torque generated by the motor is monitored, and the brake is operated to limit rotation and power supply cut-off is implemented when a predetermined torque value is reached, allowing for precise control and pressure application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a hydraulic cylinder is used to move the tail stock and apply pressure, then the tail stock can be moved and pressure applied to the workpiece, but large space is required for installation of the cylinder mechanism and oil pressure circuit

Engineering Contradiction:
Improvepressure forceVSAvoidinstallation space
Core Design Contradiction:
ForceVSArea of stationary object

Solution Approach 1:

The patent replaces the hydraulic cylinder system with a ball screw mechanism driven by a motor. The motor rotates the ball screw, which converts rotational motion into linear motion of the tail stock through the screw thread. This mechanical substitution eliminates the need for hydraulic fluid circuits and large hydraulic components, significantly reducing the space required for installation while maintaining the ability to apply pressure force to the workpiece.

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

Solution Approach 2:

The patent changes the control parameter from hydraulic pressure to motor torque. By detecting the torque generated by the drive motor, the system can precisely control the pressure force applied by the tail stock. When the torque reaches a predetermined reference value, the brake is operated to limit rotation, thereby controlling the pressure force without requiring complex hydraulic pressure reducing valves.

Inventive Principle:
Principle #35Parameter changes

2Force

If a hydraulic cylinder is used to control movement and pressure, then pressure force can be applied to the workpiece, but complicated and cumbersome operations are required for control due to manual pressure reducing valve and slow oil pressure change

Engineering Contradiction:
Improvepressure forceVSAvoidcontrol operation
Core Design Contradiction:
ForceVSEase of operation

Solution Approach 1:

The patent replaces the hydraulic control system with an electric motor and brake system. The motor drives the ball screw, and the brake limits rotation to control the tail stock movement and pressure application. This substitution eliminates manual pressure reducing valves and hydraulic fluid dynamics, enabling fast and simple control through electrical signals and torque detection.

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

Solution Approach 2:

The patent implements a feedback control mechanism by detecting the torque generated by the drive motor. When the detected torque reaches a predetermined reference value, the system automatically operates the brake to limit rotation of the ball screw. This closed-loop feedback control eliminates the need for manual pressure adjustment and enables speedy, automatic control of the pressure force applied to the workpiece.

Inventive Principle:
Principle #23Feedback

3Force

If a hydraulic cylinder is used, then pressure can be applied to the workpiece, but the change in oil pressure is slow making it unsuitable for speedy control

Engineering Contradiction:
Improvepressure forceVSAvoidcontrol speed
Core Design Contradiction:
ForceVSSpeed

Solution Approach 1:

The patent replaces the hydraulic system with an electric motor-ball screw-brake system. Electrical control signals can be transmitted and responded to almost instantaneously, and the motor can rapidly adjust its torque output. The brake can also be activated quickly to limit rotation. This mechanical-electrical system eliminates the slow fluid pressure changes inherent in hydraulic systems, enabling speedy control of the tail stock movement and pressure application.

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

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 solution enables faster control and efficient use of space compared to hydraulic cylinders, ensuring a secure pressure force for holding workpieces with the ball screw mechanism.

Implementation Method 1

a ball screw (2) which rotates to move the tail stock (1)

Methodology Applied
Scientific EffectScrew mechanism: Screw

Implementation Method 2

operating a brake (4) to limit a rotation of the ball screw (2)

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

a drive motor (3) to drive the ball screw (2)

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentEP2946876B1Moving-type tail stock
Publication Date: 2021.03.03 MATSUURA MACHINERY CO LTD
  • EP2946876B1 patent drawingFigure 1(a)~2
  • EP2946876B1 patent drawingFigure 3
  • EP2946876B1 patent drawingFigure 4(a)~4(b)

AI summary

A structure of a tail stock moving mechanism is provided, in which a tail stock that holds a workpiece with a predetermined pressure force is moved by means of a ball screw and in which the control required for holding the workpiece with the predetermined pressure force is implemented. The above is accomplished in predetermined order wherein, in a step at which the tail stock (1) that holds a position of the workpiece (5) and that is supported by a ball screw (2), torque generated by a drive motor (3) that drives the ball screw (2) is detected, and in a step at which the torque reaches a predetermined reference value, and then operation of a brake (4) to limit rotation of the ball screw (2) and cutting off of an input from a power supply to the drive motor (3) are performed.