JPH0199720A - Jig for correcting flatness of thin sheet - Google Patents

Abstract

PURPOSE:To improve the flatness and yield of a thin sheet by arranging nipping blocks at least one of which is movable and opposite to each other at the inside an outer frame for containing the thin sheet and setting the coefficient of expansion of the material of the outer frame at a smaller value than that of the nipping blocks. CONSTITUTION:There is provided an outer frame 3 in which a thin sheet 2 such as Mo material, etc., is contained and the nipping blocks 4 are arranged face to face inside the outer frame. In this case, at least one of the nipping blocks is made movable by a nipping bolt 5 to nip the thin sheet 2 with a prescribed compression force. Further, the coefficient of expansion of the material of the outer frame 3 is set at a smaller value than that of the material of the nipping blocks 4. When the thin sheet 2 nipped by the nipping blocks 4 is heat-treated, the force for tightening and correcting the nipping blocks 4 is increased because the amount of expansion of the outer frame 3 is small. In addition, since a prescribed flatness can be surely obtained, the yield of the product is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flatness correction jig for a thin plate made of molybdenum or the like used in an X-ray tomography device (X-ray CT device) or the like.

[Background of the invention]

As shown in Fig. 4, the X-ray CT device receives the X-rays 10 emitted from the X-ray tube in the shape of a beam after passing through the subject, and transmits the X-rays in the width direction of the beam. The detector 11 detects the intensity distribution of the intensity distribution.

That is, when the beam width of the received X-ray 10 is t.

In order to obtain a predetermined resolution, a predetermined number of molybdenum thin plates 2 are arranged so as to equally divide the beam width t.

Then, X-rays 1 jump between each molybdenum thin plate 2.
A cross-sectional image of the object is obtained from the output signal of the detector 11, which extracts the zero intensity due to its ionization effect.

Therefore, if the molybdenum thin plate 2 used in such a detector 11 is curved, the mounting plate 2 becomes an obstacle and X-rays cannot completely pass through the gap between the adjacent molybdenum thin plates 2. This results in an error in the intensity measurement of Xsl.

For this reason, the flatness of the molybdenum thin plate for X-ray CT equipment is
As shown in FIG. 5, when the molybdenum thin plate 2 is placed on an ideal plane (surface plate) 12, the distance H between the highest displacement point of the thin plate 2 and the ideal plane 12 is required to be 5 μmη or less. There is.

[Prior art]

Conventionally, thin molybdenum plates are generally formed by punching from a rolled material wound into a coil shape or from a flat plate as rolled, so that the molybdenum thin plate is slightly curved.

Therefore, in order to use it as a molybdenum thin plate for an X-ray CT device, it must be flattened to have ultra-flatness.

As a method for forcing flatness, a molybdenum thin plate 2' punched from a conventionally rolled molybdenum material is heat-treated at a temperature near the recrystallization temperature (approximately 1000°C) for 60 minutes, and then sandwiched between tungsten heat-resistant rigid plates having a predetermined flatness. How to press.

Alternatively, as shown in Japanese Unexamined Patent Publication No. 58-39769, a thin molybdenum plate 2' punched into a predetermined shape may be used.
As shown in FIG. 6, the molybdenum plates 2' are stacked so that the warp direction is reversed, and a liquid having good affinity for molybdenum is interposed between the stacked molybdenum thin plates 2'. As shown in the figure, pressure is applied between heat-resistant rigid plates 13 having a predetermined flatness by the weight of a weight 14, and
A method of performing heat treatment at a temperature of ~1050°C for 20 to 50 minutes is known.

[Problems with conventional technology]

However, in the former method, a flatness of only about 15 μm can be obtained and it cannot be used as a molybdenum thin plate 2 for an X-ray CT device.

In the latter case, although it is possible to obtain a molybdenum thin plate 2' with a flatness of about 5 μm, it is economically disadvantageous to arrange the stamped molybdenum thin plates 2' so that the warp direction is reversed. Not only could it not be mass-produced, but since the clamping force was applied using the weight 14, it was not possible to completely straighten it, resulting in problems such as poor yield.

[Failure to solve the problem]

This invention comprises an outer frame 3 capable of housing a thin plate 2 punched into a predetermined shape, and a clamping block 4 facing each other inside the outer frame 3, and at least one of the clamping blocks 4 being movable. The structure is characterized in that the outer frame 3 is made of a material whose expansion coefficient is smaller than that of the clamping pressure block 4.

〔Example〕

The present invention will be described below with reference to nine embodiments.

First, as shown in Figure 1, the desired thickness (0,1 to 0,3
A molybdenum rolled material 1 (0.2 m in this example), which had been rolled to a diameter of 9 mm) and whose surface had been chemically treated and cleaned, was punched out using a punching die to form a predetermined shape (in this example, a width of 28 ta).
A thin molybdenum plate 2 with a length of 35 mm is punched out.

During this punching process, the rolled material 1 is punched out so that its short sides are parallel to the longitudinal direction.

After the punched molybdenum thin plate 2 is deburred, it is ultrasonically cleaned with a cleaning agent such as methanol or soap water, and then dried.

This cleaning process removes fine dust on the surface of the thin molybdenum plate, thereby preventing scratches on the surface of the thin molybdenum plate 2 or uneven pressurization caused by post-processing.

As shown in FIGS. 2 and 3, the molybdenum thin plate 2 formed in this manner is attached to an outer frame 3 in which the molybdenum thin plate 2 can be housed, and clamping blocks 4 provided on both inner surfaces of the outer frame 3.
A plurality of thin molybdenum plates 2 are inserted between the straightening jig 6, at least one of which is movable by the clamping bolt 5.
They are clamped with a pressing force of 600 kg/cm2 so as to be stacked.

At this time, the number of thin molybdenum plates 2 held between the blocks is preferably about 600, and the direction of warpage is completely irrelevant.

The material of the outer frame 3 and the clamping pressure block 4 is, for example, molybdenum, which has a small coefficient of expansion.

The clamping pressure block 4 is made of a material having a large coefficient of expansion, such as iron.

The larger the difference in expansion coefficient between the outer frame 3 and the clamping pressure block 4, the better.

This is because when heated during the subsequent heat treatment, if the expansion of the outer frame 3 is small and the expansion of the clamping pressure block 4 is large, the dimolybdenum thin plate 2 is strongly tightened by the expansion of the clamping pressure block 4, and the molybdenum thin plate 2 is This is to ensure that the corrective action is taken.

The molybdenum thin plate 2 thus clamped by the straightening jig 6 was charged into a molybdenum boat, placed in a hydrogen furnace, and heat-treated at 1020° C. for 60 minutes in a reducing atmosphere.

Remove after cooling.

In this heat treatment, the higher the heat treatment temperature, the lower the molybdenum thin plate 2.
It is easy to achieve flatness, but if it is higher than the recrystallization temperature, the molybdenum thin plate becomes brittle, so the
It is preferable to select a temperature of about 0°C, and the heat treatment time is 40~
About 60 minutes is preferable.

The flatness of the molybdenum thin plate 2 obtained in this way is 9
5.g-cent or more was within 4 to 5 μm.

〔Effect of the invention〕

According to the present invention, it is possible to economically obtain a thin molybdenum plate with a flatness of 5 μm or less.

[Brief explanation of the drawing]

Fig. 1 is a state diagram of punching a thin molybdenum plate from a rolled molybdenum material, Fig. 2 is a plan view of the correction jig of the present invention, Fig. 3 is a side view of the same, and Fig. 4 is a diagram of the detector of an X-ray CT device. FIG. 5 is a schematic diagram of a flatness measuring jig, and FIGS. 6 and 7 are side views of a conventional device. 2... Molybdenum thin plate, 3... Outer frame, 4... Clamping pressure block, 5... Clamping bolt, 6... Correction jig. U Figure 5

Claims (1)

[Claims] (1) An outer frame capable of storing a thin plate punched into a predetermined shape and a clamping block are provided inside the outer frame to face each other, and at least one of the clamping blocks is movably supported, and A flatness correction jig for a thin plate, characterized in that the frame is made of a material whose expansion coefficient is smaller than that of the clamping pressure block.