JPH0249529Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a unit that measures the surface shape of objects to be measured, such as models and workpieces, by point contact with a probe.The purpose of this invention is to reduce the weight of the unit and improve its motion performance. The aim is to streamline measurement work and improve position measurement accuracy.

Columns are set up on the bases on both the left and right sides of the surface plate on which the object to be measured is placed, and a cross rail is installed on the side rails installed at the top end of the column so that it can run freely along the side rails so as to straddle the surface plate. A sliding body is mounted on this cross rail so as to be movable in a direction perpendicular to the direction of the side rail, and a ram having a sensor head and a probe at its tip is provided so as to be movable up and down in the direction of the axis of the pencil. Measuring machines that move to follow the surface shape of the object to be measured and bring it into point contact are known.

The ram of this measuring machine is made of the same iron material as the base, column, cross rail, and sliding body to avoid measurement errors due to thermal expansion. Therefore, the ram has a considerable weight, and increasing the moving speed deteriorates the positioning accuracy, making it impossible to improve the movement performance in order to streamline measurement work.Therefore, it is difficult to improve the movement performance without reducing the positioning accuracy. It was necessary to reduce the weight of the ram.

However, in order to reduce the weight of the ram, it is necessary to use a lightweight metal or other material that is different from the material of the base, column, cross rail, and sliding body of the measuring machine, due to differences in thermal expansion. There was a problem of measurement error.

The present invention provides a measuring unit in which the ram is made of a lightweight material different from the material of the main body of the measuring machine, and which avoids measurement errors due to thermal expansion.

Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a surface plate on which an object W to be measured is placed. A column 3 is erected on a base 2 installed on the left and right sides of the surface plate 1, and a side rail 4 having a guide rail 5 is fixed to the upper end of the column 3.

A cross rail 6 is movably mounted on the guide rail 5 so as to straddle the surface plate 1, and a measuring unit according to the present invention is mounted on this cross rail 6.

The measuring unit is mounted on the guide surface 7 of the cross rail 6, and includes a sliding body 8 that is movable in a direction perpendicular to the direction of the guide rail 5, and a feed screw 12 provided on the sliding body 8 in the vertical axis direction. Natsuto 1
The ram 9 is attached to a vertical guide member 20 fixed to the slider 8 as shown in FIG.
A guide rail 21 that protrudes further is slidably guided. Further, a sensor head 10 and a probe 11 are provided at the tip of the ram 9. Reference numeral 13 denotes a ram feed motor that rotationally drives the feed screw 12.

In the present invention, the ram 9 is connected to the base 2, the column 3,
Side rail 4, guide rail 5, cross rail 6
The ram 9 is made of a lightweight metal such as aluminum or synthetic resin, which is different from the iron material of the measuring machine body and the sliding body 8, and the scale base 16 of the scale 15 made of a material with the same expansion coefficient as the measuring machine body is attached to the ram 9. The tip of the ram 9 is used as a mounting reference, and the other end is fixed so as to be allowed to move relative to the ram 9. As an example of the fixing means, as shown in FIG. 1, the scale base 16 is fixed at the tip of the ram 9 with a fixing pin 17, and the scale base 16 is
6 is provided with a long hole in the axial direction of the ram 9, and the presser bolt 1 is
Install in step 8. Further, as shown in FIG. 3, the lower end of the scale base 16 is engaged with the tip surface of the ram 9,
A structure in which this engaging portion is fixed with a fixing bolt 22 may also be used. A reading head 19 is fixed to the slider 8 in the vicinity of the scale 15.

Since the present invention has the structure as described above, the ram 9
It is extremely lightweight, maintains sufficient positioning accuracy even when moving speed is increased, and measurement work time is significantly shortened due to improved motion performance. Furthermore, the scale base 16 of the scale 15 attached to the ram 9 is made of a material with the same coefficient of expansion, and the ram 9 is made of a material with the same expansion coefficient. It has a function of correcting the error in the measurement value by the reading head 19 to zero by the mounting structure.

That is, the ram 9 connects the measuring instrument body and the sliding body 8.
If the material is the same as that of iron, the downward extension of the ram 9 starting from the nut 14 is canceled by the upward displacement of the column 3 of the measuring machine body, and the tip position of the ram 9 is maintained at a nearly constant position. However, when the ram 9 is made of light metal such as aluminum or synthetic resin, the scale base 16 extends further downward than the ram 9 made of iron, but the scale base 16 is attached to the fixing pin 17 or the fixing pin 17. Since it is fixed to the ram 9 by bolts 22, the scale 15 read by the reading head 19 is also displaced downward, and this relative displacement is read by the reading head 19 and corrected.

In this case, the scale base 16 is made of iron, which is the same material as the measuring machine body and the sliding body 8, as in the conventional case, so the amounts of extension due to thermal expansion of these elements cancel each other out.

As described above, the present invention reduces the weight of the measuring unit by constructing the ram from a lightweight material.
Even if the ram is made of a material with a linear expansion coefficient different from that of the measuring machine body, the scale attached to the ram can improve movement performance and positioning accuracy, and the scale base can be attached to the ram tip. By fixing the ram in the direction of the other end to allow relative movement to the ram and moving it by an amount equal to the downward expansion and contraction of the ram from the fixed center, the reading head can read and measure the measured value without error. It has the effect of

[Brief explanation of drawings]

Figure 1 is a front view of the present invention, Figure 2 is Figure 1-
3 is a cross-sectional view of a main part showing a modification of the scale base mounting structure according to the present invention. 1...Surface plate, 2...Base, 3...Column, 4
...Side rail, 6...Cross rail, 8...
Sliding body, 9... Ram, 10... Sensor head, 1
1...Probe, 12...Feed screw, 14...Nut, 15...Scale, 16...Scale base, 17...Fixing pin, 18...Press bolt, 1
9...reading head, 22...fixing bolt.

Claims (1)

[Scope of utility model registration request] A ram with a detector attached to the main body of the measuring machine is slidably provided, and this ram is made of a lightweight material such as a lightweight metal or synthetic resin that has a different coefficient of expansion from the main body of the measuring machine, and has the same expansion coefficient as the main body of the measuring machine. A scale base having a coefficient is fixed with the tip of the ram as a mounting reference and the other end is allowed to move relative to the ram, and a scale is integrally attached to this scale base. A lightweight measuring unit characterized in that a reading head for reading relative displacement is provided on the measuring machine main body.