JPS6227304B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a screw structure mainly used in a measuring machine and a method for manufacturing the same.

Many measuring machines employ precise screw structures. This is because, for example, when used in the drive section of a micrometer, the structure is convenient for not only ensuring accuracy but also for obtaining a constant measuring force. In other words,
This is because the relative position between two interlocking objects can be fixed at any position. However, on the other hand,
It can also be said to be the part that is most likely to wear out because it receives the force from the measuring force. Therefore, it is desired to enhance wear resistance while maintaining initial accuracy.

Recently, the use of ceramics in measuring instruments has been proposed due to its advantages such as wear resistance, light weight, low thermal expansion, and electrical insulation properties. However, materials such as the above-mentioned micrometer have not yet been made of ceramic. This is because it is extremely difficult to obtain a precise screw structure that satisfies processability and economic efficiency from ceramic materials. This is because conventional metal processing methods are not applicable to ceramic materials due to their strength. Therefore, due to accuracy issues, grinding must be used, but since there is currently no machine that can grind female threads with a small diameter of 12 mm or less, it is necessary to use a thread structure made of the same material, that is, a male and female thread structure. This means that it cannot be obtained. On the other hand, if the diameter is large, the practical value decreases in terms of accuracy, economy, and operation due to the nature of the measuring device.

Therefore, conventional measuring instruments using ceramics, such as those disclosed in Japanese Patent Application Laid-open No. 57-19604, have only consisted of sliding main scales and vernier scales made of ceramics to maintain a constant measuring force. A situation arises in which separate means must be added for this purpose, and as a result, the practical value is low.

SUMMARY OF THE INVENTION An object of the present invention was made in view of the above problems, and it is an object of the present invention to provide a ceramic screw structure and a method for manufacturing the same.

Therefore, the thread structure of the present invention has a male threaded member made of a ceramic material, and a female threaded member in which two or more male threaded pieces cut out from the male threaded member of the same type and thread pitch as the male threaded member are arranged on the inner peripheral surface of the female threaded material. The present invention aims to provide a screw structure that can be made of ceramic even for relatively small diameter screws.

Further, in the manufacturing method of the present invention, two male threaded members with the same thread pitch are formed from a ceramic material, one of the male threaded members is cut in the axial direction to create a plurality of male threaded pieces, and then the male threaded pieces are screwed. A female threaded member is formed by fixing the part on the inner circumferential surface of the female threaded material with the part inside, and this female threaded member and the other male threaded member are screwed together to manufacture a set of screws, thereby creating a screw with a relatively small diameter. The present invention aims to provide a method for manufacturing a threaded structure that can also be made of ceramic.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a micrometer to which the screw structure of the present invention is applied. In the figure, an anvil 2 made of a ceramic material is fixed to one end of a U-shaped frame main body 1 and to the inner surface facing the other end. Further, the frame body 1
The inner end of a cylindrical outer sleeve 3 is integrally fixed to the outer surface of the other end, and a spindle 5 made of a ceramic material is attached to the anvil 2 through a cylindrical inner sleeve 4. It is inserted so that it can move forward and backward. On the outer peripheral surface of the outer sleeve 3, scales 6 are carved at 0.5 mm intervals along the axial direction.

Further, the spindle 5 is formed with a male threaded portion 7 as a male threaded member with a pitch of 0.5 mm extending from the approximate center to a slightly nearer side of the outer end, and the outer end of the outer sleeve 3 A thimble 8 and an operation knob 9 which are slidably fitted in and rotate integrally with the spindle 5 are respectively attached. A scale 10 is engraved on the outer peripheral surface of the inner end of the thimble 8, dividing the outer periphery into 50 equal parts. Further, the operation knob 9 is provided with a ratchet mechanism inside, and is designed to idle relative to the thimble 8 and the spindle 5 when a measurement pressure of a certain pressure or more is applied to the spindle 5.

Further, as shown in FIG. 2, the inner sleeve 4 is provided with three points at an interval of 120 degrees in the circumferential direction at an end opposite to the end fixed to the frame main body 1, that is, an outer end. A groove 11 is formed along the axial direction, and threaded portions 12 are screwed into the male threaded portion 7 of the spindle 5 at 120 degree intervals on the inner circumferential surface of the outer end. Three externally threaded pieces 13 made of ceramic material are provided. A taper nut 14 for expanding or contracting the inner diameter of the outer end of the inner sleeve 4 in the radial direction is screwed into the threaded portion 12. Thereby, the clearance between the male threaded portion 7 of the spindle 5 and the male threaded piece 13 can be adjusted.

Here, a method for manufacturing the male screw piece 13 will be explained. For this, as shown in FIG. 3, a male threaded shaft 21 made of ceramic material and having the same thread pitch as the male threaded portion 7 is cut to a predetermined length.
Two male threaded members 22 and 23 are formed, and one male threaded member 23 is cut in the axial direction to produce a plurality of circumferentially divided male threaded pieces 13. In order to attach this male threaded piece 13 to the inner sleeve 4, which is a female threaded material, the threaded portion side is turned inside and fixed by, for example, adhesive. As a result, a female threaded portion made of ceramic that is threadedly engaged with the male threaded portion 7 is constructed.

Note that the other male threaded member 22 is connected to the male threaded portion 7.
It can also be used as In this case, the spindle 5 may be constructed by connecting a shaft of a predetermined length to both ends of the male threaded member 22, or the male threaded shaft 21 may be formed into the shape of the spindle 5 in advance during manufacture.

The micrometer configured in this way is
It is used in the same way as a regular micrometer. In other words, when the thimble 8 is rotated, the spindle 5 moves forward and backward relative to the anvil 2 according to the thread pitch of the male threaded portion 7 and the male threaded piece 13.
If the object to be measured is held between the anvil 2 and the spindle 5, the distance between the anvil 2 and the spindle 5, that is, the dimension of the object to be measured can be read from the scales 6 and 10.

Therefore, according to this embodiment, the male threaded part 7 provided on the spindle 5 side is made of a ceramic material, and the female threaded part to be screwed with this male threaded part 7 is made of the same material as the male threaded part 7. Since the plurality of male screw pieces 13 cut out from the male thread member 23 of the screw pitch are attached to the inner circumferential surface of the inner sleeve 4, it is possible to provide a micrometer whose screw drive portion is made of ceramic. Since this can improve the wear resistance of the drive section, the initial measurement accuracy of the micrometer can be maintained over a long period of time.

In particular, in this embodiment, a male threaded member 23 made of ceramic material is cut in the axial direction to form a plurality of male threaded pieces 13 divided in the circumferential direction, and these male threaded pieces 13 are used as female threaded material. Since the female screw member is configured by being attached to the inner circumferential surface of the inner sleeve 4, it is possible to manufacture a small diameter female screw made of ceramic, which has been difficult in the past. Furthermore, since only the male thread machining is required, manufacturing is extremely easy, and improvements in accuracy and cost can be expected.

In addition, since the three male threaded pieces 13 are arranged on the inner circumferential surface of the inner sleeve 4, as long as the thread pitch is the same, female threads with different diameters can be easily manufactured. Since the joint surface can be made smaller, the sliding resistance can be reduced. Furthermore, since the diameter of the inner sleeve 4 can be changed, the male threaded portion 7 and the male threaded piece 13 can be changed.
The clearance can be adjusted. In addition, since ceramic materials have electrical insulating properties, they have the advantage of not causing magnetic problems even if an electrical encoder is used in the detection section, for example.

In the above embodiment, the entire spindle 5 is made of ceramic, but only the male threaded portion 7 may be made of ceramic. Further, the materials of the male threaded portion 7 and the female threaded portion may have different components as long as they are included in ceramic. Further, in the above embodiment, the three male threaded pieces 13 are arranged in the inner sleeve 4 to form the female threaded portion, but the number of male threaded pieces 13 may be at least two or more. Further, in the above description, an example was shown in which the present invention is used in a screw drive section of a micrometer, but the present invention is not limited to micrometers, but can be used in various measuring instruments, machine tools, etc. that have a screw structure.

As described above, according to the present invention, it is possible to provide a screw structure and a method for manufacturing the same that can be made of ceramic even for a screw having a relatively small diameter.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view showing one embodiment of the present invention, Fig. 2 is an enlarged perspective view of the main part, and Fig. 3
The figure is an explanatory view showing the manufacturing process of the male screw piece. 4...Inner sleeve as female thread material, 7
...Male thread part as a male thread member, 13...Male thread piece, 21...Male thread shaft, 23...Male thread member.

Claims (1)

[Scope of Claims] 1. A male threaded member made of a ceramic material, and a female threaded member in which two or more male threaded pieces cut from the male threaded member of the same type and thread pitch as the male threaded member are arranged on the inner peripheral surface of the female threaded material. A screw structure. 2. The thread structure according to claim 1, wherein the inner circumferential surface of the female thread material is configured to be expandable and contractible in the radial direction. 3 Form two male threaded members with the same thread pitch from a ceramic material, cut one of the male threaded members in the axial direction to create a plurality of male threaded pieces, and then insert the male threaded pieces into a female threaded material with the threaded portion inside. A method for manufacturing a threaded structure, characterized in that a female threaded member is fixed to an inner circumferential surface to form a female threaded member, and the female threaded member and the other male threaded member are screwed together to produce a set of screws. 4. Claim 3 is characterized in that two male threaded members are formed by cutting one male threaded shaft made of a ceramic material with a male thread formed on the outer periphery in a direction perpendicular to the axial direction of the shaft. A manufacturing method for a screw structure.