Measuring and testing – Surface and cutting edge testing – Roughness
Reexamination Certificate
1999-06-16
2001-02-20
Bonck, Rodney H. (Department: 3681)
Measuring and testing
Surface and cutting edge testing
Roughness
C074S089100
Reexamination Certificate
active
06189375
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a driving arrangement for measuring instruments of a type having a movable element which is movable relative to the main body of the measuring instrument so as to carry out measurement of an object to be measured, through movement of the movable element, and a measuring instrument incorporating the driving arrangement.
2. Prior Art
Conventionally, there are known measuring instruments having a movable element which is movable relative to the body of the measuring instrument so as to carry out measurement of an object to be measured, through movement of the movable element. The known measuring instruments include a surface roughness measuring instrument which has a stylus as the movable element, which is moved along a measuring surface of an object such that displacement of the stylus in a direction orthogonal to the direction of movement of the stylus is detected to thereby measure the surface roughness of the object.
The known surface roughness measuring instrument has a driving unit for moving the stylus along the measuring surface of the object, which is comprised of a feed screw shaft supported on a base via a rolling bearing or the like in a fashion extending parallel with the moving direction of the stylus, a motor drivingly coupled to the feed screw shaft, a nut-shaped member threadedly fitted on the feed screw shaft in a fashion being permitted to move only axially of the feed screw shaft, and a roughness sensor having the stylus coupled to the nut-shaped member.
With this arrangement, as the feed screw shaft is rotated by the motor, the nut-shaped member is moved axially of the feed screw shaft while being restrained from rotating, whereby the stylus of the roughness sensor is moved along the measuring surface of the object in synchronism with the movement of the nut-shaped member. At this time, the stylus of the roughness sensor is displaced in a direction orthogonal to the moving direction thereof due to the surface roughness of the object. By detecting the displacement, the surface roughness of the object can be measured.
In the driving unit of the known surface roughness measuring instrument, however, vibrations are generated from mechanical components such as the motor, feed screw shaft, rolling bearing, and nut-shaped member. Therefore, means have to be provided for absorbing such vibrations, which incurs an increase in the cost and time. What is worse, in the surface roughness measuring instrument in particular, such vibrations form a serious obstacle to measuring accuracy, making it impossible to increase the degree of measuring precision.
Besides, the driving unit structure comprised of the motor, feed screw shaft, rolling bearing, nut-shaped member, and others is large in weight, providing a factor of spoiling the weight balance of the entire measuring instrument.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a driving arrangement for measuring instruments, which can contribute to increase of the degree of measuring precision through reduction of vibrations to be generated, as well as to achievement of a good weight balance of the entire measuring instrument, and a measuring instrument incorporating the driving arrangement.
To attain the above object, the present invention provides a driving arrangement for a measuring instrument having a body, and a movable element being movable relative to the body, wherein measurement of an object to be measured is carried out through movement of the movable element, comprising driving and guide means mounted on the body of the measuring instrument, the driving and guide means including a driving cylinder having a piston received therein for axial movement, the driving and guide means being operable to move the movable element in synchronism with the axial movement of the piston, and hydraulic fluid control means arranged at a location remote from the body of the measuring instrument, for supplying hydraulic fluid to the driving cylinder of the driving and guide means to cause the axial movement of the piston of the driving cylinder.
With the above arrangement, when hydraulic fluid is supplied to the driving cylinder of the driving and guide means by the hydraulic fluid control means, the piston of the driving cylinder is moved by the hydraulic fluid, whereby the movable element is moved in synchronism with the movement of the piston. According to the present driving arrangement, in the body of the measuring instrument the vibration generating factor is reduced to the maximum possible degree. That is, the measuring instrument body is only provided with the driving and guide means including the driving cylinder with the piston received therein for axial movement. As a result, the measuring instrument body is susceptible to vibrations substantially reduced as compared with the construction of the conventional driving unit, whereby a significantly higher degree of measuring precision can be achieved.
Further, while the conventional driving unit has many component parts which are large in weight, such as the motor, feed screw shaft, rolling bearing, and nut-shaped member, the driving arrangement according to the present invention has a reduced weight, which can improve the weight balance of the entire measuring instrument.
Preferably, the driving and guide means comprises a base, guide means mounted on the base in a fashion extending parallel with the moving direction of the movable element and supporting the movable element for axial movement, the driving cylinder supported by the base in a fashion extending parallel with the guide means and having the piston received therein for axial movement, and synchronous moving means for moving the movable element in synchronism with the axial movement of the piston of the driving cylinder.
With this arrangement, the movable element is supported by the guide means for axial movement such that it moves in synchronism with the axial movement of the piston of the driving cylinder. As a result, the driving arrangement has a simple structure but can move the movable element in a stable manner.
Preferably, the guide means comprises a guide shaft mounted on the base in a fashion extending parallel with the moving direction of the movable element, and a holding member movably mounted on the guide shaft and holding the movable element.
More preferably, the guide shaft and the holding member form a position sensor for sensing a position of the movable element during movement.
Preferably, the synchronous moving means comprises a follow-up tubular element movably fitted on the driving cylinder and coupled to the holding member for movement in unison therewith, the follow-up tubular element being formed of a magnetic material and movable in synchronism with the axial movement of the piston of the driving cylinder, which is formed of a magnet, to thereby move the movable element.
Alternatively, the synchronous moving means may comprise a piston rod having one end thereof coupled to the piston of the control cylinder for movement in unison therewith and another end portion thereof projected outwardly from the control cylinder, and a coupling rod coupling the nut-shaped member to the other end portion of the piston rod for movement in unison therewith, the synchronous moving means being movable in synchronism with the axial movement of the nut-shaped member, to thereby move the piston of the control cylinder.
Preferably, the hydraulic fluid control means comprises a base, a feed screw shaft rotatably supported by the base, a motor for rotatively driving the feed screw shaft, a nut-shaped member threadedly fitted on the feed screw shaft for axial movement in unison with rotation of the feed screw shaft, a control cylinder mounted on the base in a fashion extending parallel with the feed screw shaft and having a piston received therein for axial movement, synchronous moving means for moving the piston of the control cylinder in synchronism with the axial movement of the nut-s
Bonck Rodney H.
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Mitutoyo Corporation
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