JPH09133136A - Manufacture of dry bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a plating bath be enough merely passing a narrow material, less in the charge of a plating solution, plating work performable in succession, and to improve the extent of productivity by carrying out the plating of a lubricative metal after forming it into a narrow material. SOLUTION: Metals in use for plating are recommended to be lubricative such as tin, lead or these alloys, and as to the plating of a dry bearing, this tin is suitable in particualr. A wide plural-layer material 12 is rewound as in an arrow and fed to a slitter 13. At this slitter, this wide plural-layer material is cut off in the specified width, for example, 20mm in width or width of the dry bearing in the longitudinal direction, namely, into plural pieces of narrow materials 14. A coil-form chamfering narrow material 17 is rewound as in an arrow, and it is led into an electroplating bath 18, and tin's electroplating is performed on a ferro-part, turning to a plated narrow material 19. Therefore this coil-form plated narrow material 19 is rewound as in the arrow, and then plate thickness is accurately adjusted through a precision mill roller 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a dry bearing which is oil-free and exhibits good lubricity for a long period of time.

[0002]

2. Description of the Related Art A dry bearing is a bearing in which a metal plate having a high mechanical strength is used as a back metal, and a multi-layer material in which a sliding material is adhered to the back metal has a cylindrical shape.

Generally, a dry bearing is one in which an iron plate is used for the back metal and a polymer resin such as polytetrafluoroethylene resin is used for the sliding material, and the sliding material itself is excellent without lubrication. Machines and equipment that cannot lubricate due to lubricity, such as office automation equipment such as copy machines, computers, facsimile machines, printers, hydraulic machines such as axial piston pumps and gear pumps, automatic adjustment mirrors for automobiles, power windows, wipers, etc. It is used for the rotating and sliding parts of.

In order to form the backing metal of the dry bearing and the sliding material in multiple layers, an adhesive may be used to bond them together. However, those joined with an adhesive are produced by rotating a shaft rotating at a high speed and a high load. It was not enough to support the shaft, and the backing metal and the sliding material sometimes separated. Therefore, conventionally, when the backing metal and the sliding material are formed in multiple layers, a reliable impregnation method is used.

In this impregnation method, a metal powder is sprinkled on one surface of the back metal and sintered to form a porous metal layer. Then, a sliding material is placed on the porous metal layer, and a roller or a press is pressed on the sliding material to impregnate the sliding material into the porous metal layer. The dry bearing manufactured by rolling the multi-layered material obtained by the impregnation method peels off even if a high-speed, high-load shaft is supported because the sliding material is anchored in the porous metal layer. It has the excellent feature that it never happens.

Here, a conventional method for manufacturing a dry bearing will be described. The material of this dry bearing is explained by using an iron plate for the back metal, a bronze alloy for the powder metal to be sintered on the back metal, and a mixture of polytetrafluoroethylene resin, polyphenylene sulfide resin, and powdered lead for the sliding material. .

Bronze alloy powder is sprinkled thinly on the surface of a wide strip-shaped iron plate and sintered in a sintering furnace in an active atmosphere consisting of a mixed gas of hydrogen and nitrogen to form a porous metal layer on the iron plate. Use a sintered material. Place the dispersion of the sliding material on the porous metal layer of the wide sintered material, impregnate it with the roller, then bake the resin component and adjust the thickness with the roller to make a wide multi-layer material. To do. A wide multi-layered material is slit into a predetermined width in the longitudinal direction to form a narrow multi-layered material (hereinafter referred to as a narrow thin material). Chamfer the corner of the narrow material by cutting. The chamfered narrow material is cut into strips, and the strips are pressed into a cylindrical shape. Electroplating tin on the iron part of the cylindrical shape.

Generally, when a dry bearing is attached to an apparatus or a machine, a hole is formed at a mounting position and the dry bearing is attached to the hole. After the dry bearing is installed in the hole, it must not rotate together with the rotating shaft, so the outer diameter of the dry bearing is much smaller than the inner diameter of the hole, for example, 40 to 50 μm, so that the dry bearing may be in close contact with the hole. It is made large. Therefore,
Since the dry bearing cannot be easily installed in a slightly small hole, it is installed by press fitting with a hydraulic machine or a press.

Most of recent devices and machines for mounting dry bearings are made of aluminum having a low specific gravity in order to reduce the weight. However, since aluminum is softer than iron, when a dry bearing is press-fitted into the mounting hole, a hard back metal causes "stripping" that damages the mounting hole. If scoring occurs during press-fitting, the scraped pieces will enter the inside of the dry bearing, causing damage to the sliding material and shaft. Therefore, a lubricating metal such as tin or lead is plated on the back metal of the dry bearing so that the dry bearing can be smoothly press-fitted without causing galling at the time of mounting. The lubricious metal acts as a lubricant between the hole and the dry bearing, making it easier to press the dry bearing into the hole. Also, plating on the back metal is necessary not only to prevent galling but also to prevent rust.

In the conventional dry bearing manufacturing method,
Plating was done in the final process. The reason is that it has been considered that if plating is not performed on all the portions of the backing metal where the iron is exposed, rust occurs on the non-plated portions.

Therefore, in the conventional plating of dry bearings, each dry bearing was hung by a hanging jig serving as a negative electrode. A large number of dry bearings suspended by this suspension jig are dipped in a plating bath containing a plating solution for plating, but a large amount of dry bearings can be plated in one plating operation to improve productivity. Therefore, the plating tank used was a relatively large one.

[0012]

In a conventional dry bearing mounted on a device or machine having a rotating part, strict dimensional accuracy is not required, but a general tolerance, for example, ± 50 μm.
It was sufficient if it was within m, but the tolerance of dry bearings attached to precision equipment like OA equipment is ± 10μ.
Very strict dimensional accuracy within m has been required. However, with respect to such strict dimensional accuracy, the dry bearing manufactured by the conventional manufacturing method has a tolerance of ± 10μ after plating, no matter how precisely it is finished.
Could not be within m.

Many dry bearings have different widths, thicknesses, and outer diameters, and there are a great many types in which these are combined. Therefore, a wide variety of products must be prepared in order to keep them in stock as products, and a wide warehouse and labor-intensive management are required for the inventory of the multi-product.
However, the width of the intermediate width material with sliding material attached to the iron plate is different only in width and thickness, and the types are smaller than the types of dry bearings that are products, and the inventory is in the form of width material. Since it does not take up space if it is done, it was considered to be stocked with narrow width materials. However, when the narrow material manufactured by the conventional manufacturing method is stocked as an intermediate material, there is a problem that the back metal is rusted.

Furthermore, in the conventional manufacturing method, a large number of dry bearings are hung on the hanging jig one by one, so that the hanging work requires a lot of labor. And in order to plate many dry bearings at once, a large plating tank had to be installed. Since a large amount of plating solution is put into a large plating tank, a large amount of expensive plating solution is required, and it is costly to process a large amount of plating solution that has deteriorated and becomes unusable, which is economical. It was problematic.

Furthermore, when there is no product in stock, the conventional dry bearing manufacturing method has to go through the labor-intensive steps as described above before the product is completed after receiving an order. A long period of time was required.

The present invention is sufficiently satisfactory for use in places where strict dimensional tolerances are required, such as OA equipment, does not cause rust even when stocked with an intermediate material, and has a small plating tank. The present invention is to provide a dry bearing manufacturing method which is advantageous in terms of location because it can be completed, uses a small amount of plating liquid, and can complete a product within a short period of time after receiving an order.

[0017]

The inventors of the present invention have found that the plating on the outside of the dry bearing is necessary for press-fitting into the hole at the time of mounting, but the plating of the joint of the dry bearing is completely unrelated at the time of press-fitting. The present invention has been completed by focusing on the fact that rust is unlikely to occur because the joints are in close contact with each other, and that even if rust occurs at the joints, the bearing performance is hardly affected.

The present invention comprises a sintering step for forming a porous metal layer on the surface of a wide strip-shaped metal plate, and impregnating the porous porous metal layer with a sliding material to form a wide multi-layer material. Impregnation process, slitting process for making the multi-layered material a narrow multi-layered material (hereinafter referred to as width narrowing material), chamfering step for chamfering the narrowing width material, and plating step for plating the chamfered widthning narrow material And a plate thickness adjusting step of adjusting the thickness after plating, and a rounding step of rolling the precision width narrow material having the adjusted plate thickness into a strip material and rolling it.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An iron plate is suitable as a wide strip-shaped metal plate used in the present invention, and a metal powder for forming a porous metal layer is copper such as bronze alloy, phosphor bronze alloy, lead bronze alloy or the like. Alloys and pure copper are suitable. Using an iron plate as the back metal,
When a copper alloy or pure copper is used to form the porous metal layer, the sintering temperature is lower than the melting temperature of the copper alloy, for example, 800 to 900 ° C., in order to adhere the powder metals to each other and the powder metal and the iron plate by solid diffusion. To

The sliding material with which the porous metal layer is impregnated is mainly composed of a polymer resin such as polytetrafluoroethylene resin, polyamide resin, polyacetal resin, polyphenylene sulfide resin, etc. Alternatively, a solid lubricant such as molybdenum disulfide may be mixed. The porous metal layer is impregnated with the sliding material by pressing with a roller or a press. After impregnating the sliding material into the porous metal layer, it is fired in a firing furnace. Upon firing, the sliding material is fused and anchored on the porous metal layer, strengthening the adhesion with the porous metal layer and improving the lubricity. After firing, it is passed through a roller to adjust the thickness. The thickness tolerance here is ± 15 μm.

A wide multi-layer material having a porous metal layer impregnated with a sliding material is cut in the longitudinal direction to obtain a narrow material. The width of the narrow material is the same as that of the dry bearing.

In the lateral cross section of the narrow material, the corners are at right angles. When the dry bearing is used as it is, the inner end contacts the rotating shaft to damage the shaft, and the outer end has the dry bearing. When press-fitting into the hole to be attached, it will cause scratches that damage the hole. Therefore, chamfering is performed by slightly cutting the corner of the narrow material diagonally.

The metal used for plating in the present invention has lubricity and is tin, lead, or an alloy thereof,
Tin is suitable for plating dry bearings. The reason for plating the outside of the dry bearing is to improve the lubricity with the hole and to prevent galling when the dry bearing is pressed into the hole. The plating method may be electroplating, hot dipping, chemical plating, etc., but electroplating is most suitable in terms of uniformity and thickness control.

Even in electroplating that can obtain uniform plating, it is not necessarily uniform due to the positional relationship with the electrodes, the change in the concentration of the electrolytic solution, etc. Therefore, precise plate thickness adjustment is performed.
The plate thickness adjusting device used here is a precision roller.

The precision narrow material having the adjusted plate thickness is cut into strips according to the circumference of the dry bearings, and the strips are rolled into a dry bearing. In the rounding process here, the outer diameter accuracy must be within ± 10 μm.

[0026]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG.
FIG. 2 is a diagram illustrating each step of the present invention, and FIG. 2 is an enlarged front sectional view of a material in each step and a front view of a dry bearing obtained in the present invention.

(A) Sintering process Wide band-shaped iron plate 1 having a thickness of 1.5 mm and a width of 200 mm
Is wound into a coil. The wide strip-shaped iron plate is unwound and fed horizontally as shown by the arrow, and the bronze powder 3 is uniformly sprayed from the hopper 2 onto the iron plate. The strip-shaped iron plate on which the bronze powder is dispersed is sent to the sintering furnace 4, where the bronze powder and the bronze powder and the iron plate are sintered to form the porous metal layer 5 on the strip-shaped iron plate 1 and broadly sinter. It becomes material 6. The wide sintered material 6 is wound in a coil shape.

(B) Impregnation Step The wide sintered material 6 wound in a coil shape is unwound and fed horizontally as shown by the arrow, and the syringe 7 and the sliding material 8 are placed on the porous metal layer 5. Is placed. The sliding material is a dispersion of polytetrafluoroethylene resin mixed with polyphenylene sulfide resin, lead powder and the like. The sliding material 8 on the wide sintered material is pressed by the impregnating roller 9, and a part of the sliding material is impregnated into the porous metal layer 5. The wide sintered material 6 impregnated with the sliding material is sent to the firing furnace 10 and fired. After that, the wide sintered material 6 is
Wide thickness of multi-layer material 1
It becomes 2 and is wound in a coil shape.

(C) Slit Step The wide multi-layered material 12 wound in a coil shape is unwound as shown by the arrow and sent to the slitter 13. In the slitter 13, the wide multi-layered material is cut into a predetermined width, for example, a width of 20 mm, which is the width of the dry bearing, in the longitudinal direction to form a plurality of narrow width materials 14. The narrow material 14 is wound in a coil shape.

(D) Chamfering step The coiled narrow material 14 is rewound as shown by the arrow and sent to the chamfering device 15. In the chamfering device 15, the narrow material 1
The upper and lower portions 16 on both sides of 4 are chamfered obliquely to form a chamfered narrow material 17. The chamfered narrow strip 17 is wound into a coil.

(E) Plating Step The coiled chamfered narrow strip 17 is unwound as shown by the arrow and introduced into the electroplating tank 18 to electroplate tin on the iron portion to form a plated strip 19. Become. Plating tank 18
A plating solution 20 composed of sulfuric acid, stannous sulfate, water, etc. is charged into the chamber, and a tin anode plate 21 is arranged below. The anode plate 21 is connected to the anode (+) of the DC power source, and the chamfered narrow strip 17 is connected to the cathode (−) by the conducting portion 22. The thickness of the plating 23 on the iron plate 1 is about 3 μm. The plated narrow material 19 is wound into a coil.

(F) Plate Thickness Adjusting Process In the narrow plating material 19, the plating 23 on the iron plate portion has unevenness or uneven plating thickness as shown in (e) of FIG. Since the thickness is not sufficiently accurate in adjusting the thickness after firing, it is necessary to precisely adjust the thickness. Then, the coiled narrow strip material 19 is rewound as shown by the arrow, and the plate thickness is accurately adjusted through the precision rolling roller 24. The precision narrow material 25 having the adjusted plate thickness is wound in a coil shape.

(G) Rounding process The coil-shaped precision narrow material 25 is rewound as shown by the arrow,
The strip material 27 is cut by the cutter 26. The strip material 27 is sent to a rounding device, and is first made into a U shape by a cored bar 28 and a female die 29, and then rounded by the upper and lower rounding die 30, 30 so as to form a perfect circle. Although the dry bearing 31 is formed in this manner, the seams 32 are in close contact with each other, so that rust is less likely to occur.

The dimensional accuracy of the dry bearing obtained by the method of the present invention was within a range of ± 5 μm with respect to an outer diameter of 20 mm, which was extremely high. Further, even if the precision width narrow material which is an intermediate material in the production method of the present invention is kept in stock for a long period of time, no rust is generated, and no rust is generated from the joint in the finished product. It took only one day from the state of stocking the intermediate narrow precision material to complete the dry bearing.

[0035]

According to the present invention, since the lubricating metal is plated after the narrow material is used, the plating tank need only be small enough to pass the narrow material. Therefore, the amount of plating solution input is small. Since the narrow material has a coil shape, plating can be performed continuously, and plating productivity is improved. Also, even if stocked with plated narrow material or precision narrow material, the rust does not occur because the iron part is plated. If the plate thickness is adjusted in the state of the thin strip material, the uneven plating is flattened and the plate thickness is adjusted accurately.

The two types of combinations of plate thickness and width are
Fewer than three combinations of outer diameters. In other words, the plated narrow material and precision narrow material, which are the intermediate materials of the dry bearing, are a combination of only the plate thickness and width, and the finished product of the dry bearing is a combination of the plate thickness, width and outer diameter. There are more types of finished products. There are ten times as many dry bearing types as narrow strip types, and cylindrical dry bearings have many cavities, so they are one of the narrow strips wound in a coil.
The volume is 00 times. Therefore, if the stock is made in the form of an intermediate material of plated narrow material or precision narrow material, the intermediate material can be placed in a much smaller area than the product. In addition, since there are few types of narrow width materials, their management is easy.

When a dry bearing is ordered and production is started from a wide strip-shaped metal plate, it takes a lot of time to complete the steps as described above, and it takes a long time to complete the process. Starting with a thin material or precision width material requires only a simple process, so it can be finished in a short period of just one day and can be easily produced even after the order is confirmed.

When the plate material is electroplated, the plating thickness may not be uniform or the surface may have irregularities due to the positional relationship with the anode plate and the energization state. However, since precision rolling is performed after electroplating. You can correct the plating variation.

Further, when a wide plate material is rolled, the overall plate thickness, particularly the dimensional accuracy on both sides of the plate material, is not good. This is because the thickness of both sides of the plate will be different unless the pair of rolling rollers are slightly parallel to each other. However, in the case of a narrow plate material, even if the rolling rollers are not parallel to each other to some extent, a large difference does not appear on both sides of the plate. Therefore, if precision rolling is performed with a narrow plated material, the plate thickness accuracy becomes good.

As described above, the present invention is remarkably superior to the conventional manufacturing method in terms of economic efficiency at the time of plating, inventory, accuracy at the time of adjusting the plate thickness, production period from order receipt to product completion, etc. Is to have.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating each step of the present invention.

FIG. 2 is an enlarged front sectional view of a material in each step of the present invention and a front view of a dry bearing obtained by the present invention.

[Explanation of symbols]

 1 Wide Strip Iron Plate 3 Bronze Powder 4 Sintering Furnace 6 Wide Sintering Material 8 Sliding Material 9 Impregnating Roller 10 Firing Furnace 11 Roller 12 Wide Multi-Layer Material 13 Slitter 14 Chamfering Device 15 Chamfering Width Thin Material 18 Plating tank 19 Plated narrow material 24 Precision rolling roller 25 Precision narrow material 27 Strip material 31 Dry bearing

Claims (2)

[Claims] (A) A powder metal is uniformly dispersed on a wide band-shaped metal plate, and the powder metal is sintered in a sintering furnace to form a porous metal layer on the band-shaped metal slope. A sintering step of obtaining a sintered material; (b) an impregnation step of impregnating a wide sintered material with a sliding material and firing it into a wide multilayer material; A slit step of cutting a multi-layered material into a predetermined width in the longitudinal direction to obtain a narrow material, (d) a chamfering step of cutting a corner of the narrow material into a chamfered width material, and (e) a chamfering A plating step of plating a lubricious metal on the metal portion of the narrow strip to form a plated narrow strip, and (f) a plate thickness adjusting step of adjusting the thickness of the plated narrow strip to form a precise narrow strip ( g) A method for manufacturing a dry bearing, which comprises a step of cutting a precision narrow material into strips and rolling the cut strips. 2. The method of manufacturing a dry bearing according to claim 1, wherein the plating of the lubricating metal is plating of tin, lead, or an alloy thereof.