WO2004056531A1

WO2004056531A1 - The structure of tool head unit of polishing maching

Info

Publication number: WO2004056531A1
Application number: PCT/KR2003/001026
Authority: WO
Inventors: Sang-Dae Yoon
Original assignee: Fine Ace Technology Co., Ltd.
Priority date: 2002-12-20
Filing date: 2003-05-26
Publication date: 2004-07-08
Also published as: KR100392414B1; AU2003234857A1

Abstract

Disclosed is a finishing machine tool, and more particularly, to a head unit structure in a finishing machine tool in which a grinding bit can perform a finishing work at a uniform pressure by an automated static pressure unit and an operation system of carriage means can more stably control the finishing work in order to enhance the precision and reliability of the finishing work for a workpiece. The finishing machine tool includes carriage units movable along X-, Y- and Z-axial directions and a bit driving unit disposed at an end of the Z-axial carriage unit for machining a workpiece. The bit driving unit comprises: a spindle unit for turning a bit mounted thereon at high speed so that the bit serves to machine the workpiece; and a static pressure unit for moving the spindle unit according to pressure applied to the bit mounted on the spindle unit to maintain the pressure applied to the bit at a uniform level. The head unit structure in a finishing machine tool having the X-, Y- and Z-axial transfer directions is improved so that the rotation velocity of the bit can be precisely controlled and a finishing work can be carried out at a uniform pressure thereby increasing the precision of the finishing work. Furthermore, noises and vibrations occurring during the finishing work are reduced to improve the reliability of the finishing work.

Description

THE STRUCTURE OF TOOL HEAD UNIT OF POLISHING MACHING

Technical Field The present invention relates to a finishing machine tool, and more particularly, to a head unit structure in a finishing machine tool in which a grinding bit can perform a finishing work at a uniform pressure by an automated static pressure unit and an operation system of carriage means can more stably control the finishing work in order to enhance the precision and reliability of the finishing work for a workpiece .

Background Art

In general , a finishing work refers to a work for polishing partial faces of molded articles, which are formed from various casts such as a mold, a cold forging mold and a blank mold, like mirror faces.

The purpose of such finishing work is to minimize the surface coarseness of a molded article after milling or grinding to smoothen the surface of the molded article like a mirror f ce and maintain the precision of the surface.

Recently, various electronic devices including home appliances and OA equipments are becoming shorter in their life cycles according to particular tastes of consumers, and demand for molds for such electronic devices are consistently increasing. However, most of finishing steps which are final fabrication steps of molds are manually performed.

There has been proposed a six-axial multijoint robot for automating this finishing work. However, the robot has a precision of positioning poorer than that of a machine tool having X- , Y- and Z- axes and thus failed to satisfy coarseness and flat roughness. As a result, the finishing work has been performed by using the machine tool having X- , Y- and Z- axial feed directions.

However, the conventional machine tool for performing the finishing work must press the surface of a mold at a predetermined pressure while a rotary grinding bit is in contact with the surface of the mold in order to maintain predetermined surface precision. Further, since the machine tool does not have a static pressure unit which can regulate the compression force of the grinding bit, the mold can hardly obtain high surface precision, thereby degrading reliability of the finishing work.

Disclosure of Invention

Therefore, the present invention has been made in view of the foregoing problems and it is an object of the invention to improve a head unit structure in a finishing machine tool having X-, Y- and Z-axial feed directions so that the rotation velocity of a grinding bit can be precisely controlled and a finishing work of a workpiece can be carried out at a pressure maintained uniformly, thereby increasing the precision of the finishing work and reducing noises and vibrations occurring during the finishing work to improve the reliability of the finishing work.

To accomplish the above object, according to an aspect of the invention, there is provided a head unit structure in a finishing machine tool which includes carriage units movable along X- , Y- and Z-axial directions and a bit driving unit disposed at an end of the Z-axial carriage unit for machining a workpiece, wherein the bit driving unit includes: a spindle unit for turning a bit mounted thereon at high speed so that the bit serves to machine the workpiece; and a static pressure unit for moving the spindle unit according to pressure applied to the bit mounted on the spindle unit to maintain the pressure applied to the bit at a uniform level .

Preferably, the static pressure unit may include: a base coupled with an end of the Z-axial carriage unit; an LM guide mounted on one side of the base for guiding passage of the spindle unit; a double acting air cylinder coupled with a portion of the base and actuated by compressed air to carry the spindle unit; a pressure sensor for measuring internal pressure of the double acting air cylinder; precision regulators disposed respectively at front ends of air ports of the double acting air cylinder and functioning to feed compressed air into the double acting air cylinder at a predetermined pressure corresponding to a value of the internal pressure of the double acting air cylinder measured by the pressure sensor; and an air unit having a general regulator communicating with an air supply for feeding air having a preset value of pressure to the double acting air cylinder and the precision regulators.

Also preferably, the spindle unit may includes a fixed bracket movably coupled with the static pressure unit; a spindle motor disposed on the fixed bracket for applying torque to the bit; and a spindle head connected in series with a rotary shaft of the spindle motor by means of a coupling and having a holder for gripping and turning the bit .

Brief Description of the Drawings

Fig. 1 is a perspective view of a finishing machine tool of the present invention;

Fig.2 is a side elevation view of a head unit in a finishing machine tool of the present invention; Fig. 3 is a front elevation view of the head unit of a finishing machine tool of the invention; and

Fig. 4 is a pneumatic circuit diagram of the head unit in a finishing machine tool of the present invention.

Best Mode for Carrying Out the Invention

A preferred embodiment of the present invention will be described hereinafter with reference to the accompanying drawings .

First, as shown in Fig. 1, a finishing machine tool according to the preferred embodiment of the invention comprises a body 1, a table 50 disposed on an upper portion of the body 1 for seating a workpiece (not shown) thereon, a controller 10 disposed at one side of the body 1 for controlling the operation of the body 1, a control unit 12 mounted at the upper portion of a front portion of the body 1 and having control switches and control buttons for manipulating the controller 10, a head unit 60 and X- , Y- and Z-axial carriage units 20, 30 and 40 arranged over the table 50. The X- , Y- and Z-axial carriage units 20, 30 and 40 carry a bit 62, which is mounted on the head unit 60, along X, Y and Z axes.

The X-axial carriage unit 20 is supported by a pair of columns 22 and 24 which are disposed on the top portion of the body 1, the Y-axial carriage unit 30 is coupled with the top portion of the X-axial carriage unit 20 so that the Y-axial carriage unit 30 can be carried along both a longitudinal direction of the X-axial carriage unit 20 and a direction perpendicular thereto, and the Z-axial carriage unit 40 is mounted to one end of the Y-axial carriage unit 30 in a vertically movable fashion. The head unit 60 mounted with the bit 62 for machining the workpiece is arranged at the lower end of the Z-axial carriage unit 40. As shown in Figs. 2 and 3, the head unit 60 of a finishing machine tool of the invention includes a spindle unit 90, which is coupled with the lower end of the Z-axial carriage unit 40 and rotatably mounted with the bit 62 for machining the surface of the workpiece seated on the table 50, and a static pressure unit 80 for regulating the pressure between the bit 62 and the workpiece applied by the spindle unit 90 to a uniform level. The spindle unit 90 is provided with a bracket 91 fixed to the transport side of an LM guide 86 of the static pressure unit 80. A spindle motor 92 is arranged on the fixed bracket 91 for turning the bit 62 and has a rotary shaft 93 connected with a spindle head 96 by means of a coupling 94. At the lower end of the spindle head 96, a holder 97 is arranged for securely holding the bit 62 for machining the workpiece.

The static pressure unit 80 includes an L-shaped base 84 coupled with the Z-axial carriage unit 40. The static pressure unit 80 also includes a double acting air cylinder 82 arranged on the base 84 for vertically moving the spindle unit 90 so that the bit 62 can apply a predetermined pressure to the workpiece according to the pressure applied to the spindle unit 90. At one side of the base 84, an LM guide 86 is fixedly mounted to a piston 87 of the air cylinder 82 to guide linear motion of the spindle unit 90.

As shown in Fig.4, the static pressure unit 80 is designed to regulate the pressure of the double acting air cylinder 82 to a uniform level, and includes a pressure sensor 2 for detecting a variation in the internal pressure of the double acting air cylinder 82, an air unit 6 having a general or first regulator 5 communicating with an air supply 7 for feeding air of a preset pressure to the double acting air cylinder 82 and a pair of precision regulators 3 and 4 for maintaining the pressure of air supplied from the air unit 6 at a uniform level so as to precisely regulate the pressure of air fed to air ports 83 and 85 of the double acting air cylinder 82.

Next, the operation of the head unit structure in a finishing machine tool according to the preferred embodiment of the invention will be described hereinafter.

First, when an operator manipulates the control switches and the control buttons equipped in the control unit 12 for X- , Y- and Z-axial movement of the head unit, the controller 10 operates the X-, Y- and Z-axial carriage units 20, 30 and 40 in response to signals inputted via the control switches and the control buttons so that the bit 62 mounted on the head unit 60 is placed on a workpiece (not shown) to be subjected to a finishing work.

Then, when the operator inputs an operation signal for rotation of the bit 62, the controller 10 outputs a signal for controlling the spindle motor 92 of the spindle unit 90 to actuate the spindle motor 92 thereby implementing the finishing work of the workpiece .

In this case, the rotation speed of the bit 62 can be regulated precisely in a relatively simple manner by adjusting the rotation speed of the spindle motor 92. The static pressure unit 80 carries the spindle unit 90 for machining the workpiece so that the bit 62 contacting the workpiece remains under a constant pressure.

In the static pressure unit 80, compressed air from the air supply 7 is adjusted to a predetermined pressure by the first regulator 5 while passing through the air unit 6 and then fed to the pair of precision regulators 3 and 4 provided at the front ends of the air ports 83 and 85 of the double acting air cylinder 82. After the precision regulators 3 and 4 precisely regulate the pressure of the fed air for supply to the air ports 83 and 85 of the double acting air cylinder 82. Therefore, the compressed air fed to the air ports 83 and 85 of the double acting air cylinder 82 is regulated and fed to the air ports 83 and 85 by the precision regulators 3 and 4 so that the inside of the double acting air cylinder 82 maintains static pressure.

While the bit 62 of the spindle unit 90 machines the workpiece, when the pressure between the workpiece and the bit 62 is different from the preset pressure value the spindle unit

90 presses the movably fixed piston 87 of the double acting air cylinder 82 of the static pressure unit 80. The pressure sensor

2 equipped in the double acting air cylinder 82 detects a variation in the internal pressure of the double acting air cylinder 82 and transmits a signal indicative of a detected value of variation to the controller 10.

Then, the controller 10 controls the precision regulators

3 and 4 provided at the front ends of the air ports 83 and 85 of the double acting air cylinder in response to the signal from the pressure sensor 2 to regulate the pressure of compressed air fed into the double acting air cylinder 82 so that the internal pressure of the double acting air cylinder 82 can be maintained at the preset level .

This uniformly maintains the internal pressure of the double acting air cylinder 82, to which the spindle unit 90 mounted with the bit 62 is fixed. Therefore, when the pressure between the bit 62 and the workpiece is varied, the piston 87 of the double acting air cylinder 82 is moved so that the spindle unit 90 fixed to the piston 87 of the double acting air cylinder 82 is moved along the LM guide 86 to maintain the pressure between the bit 62 and the workpiece at a uniform level.

Industrial Applicability

According to the invention as set forth above, the head unit structure in a finishing machine tool having the X- , Y- and Z-axial transfer directions is improved so that the rotation velocity of the bit can be precisely controlled and a finishing work can be carried out at a uniformpressure thereby increasing the precision of the finishing work. Furthermore, noises and vibrations occurring during the finishing work can be reduced to improve the reliability of the finishing work.

Claims

What Is Claimed Is;

1. A head unit structure in a finishing machine tool which includes carriage units movable along X-, Y- and Z-axial directions and a bit driving unit disposed at an end of the Z-axial carriage unit for machining a workpiece, wherein the bit driving unit comprises: a spindle unit for turning a bit mounted thereon at high speed so that the bit serves to machine the workpiece; and a static pressure unit for moving the spindle unit according to pressure applied to the bit mounted on the spindle unit to maintain the pressure applied to the bit at a uniform value .

2. The head unit structure in a finishing machine tool according to claim 1, wherein the static pressure unit includes: a base coupled with an end of the Z-axial carriage unit; an LM guide mounted on one side of the base for guiding a passage of the spindle unit; a double acting air cylinder coupled with a portion of the base and actuated by compressed air to carry the spindle unit ; a pressure sensor for measuring internal pressure of the double acting air cylinder; precision regulators disposed respectively at front ends of air ports of the double acting air cylinder and functioning to feed compressed air into the double acting air cylinder at predetermined pressure corresponding to a value of the internal pressure of the double acting air cylinder measured by the pressure sensor; and an air unit having a general regulator communicating with an air supply for feeding air having a preset value of pressure to the double acting air cylinder and the precision regulators .

3. The head unit structure in a finishing machine tool according to claim 1, wherein the spindle unit includes: a fixed bracket movably coupled with the static pressure unit ; a spindle motor disposed on the fixed bracket for applying torque to the bit; and a spindle head connected in series with a rotary shaft of the spindle motor by means of a coupling and having a holder for gripping and turning the bit .