JPH05342707A - Manufacture of guide roller for magnetic tape - Google Patents

Abstract

PURPOSE:To obtain a guide roller whose high accuracy is the same as or higher than that in a case where a rod material is cut off and cut by a method wherein a primary roller whose outside diameter is a little larger than that of a product size and whose shaft-hole diameter is a little smaller than that of the product size is formed of a nonmagnetic material such as a synthetic resin or the like and the shaft-hole circumference and the outer circumference of the primary roller are cut and finished. CONSTITUTION:A primary roller 2 is formed of a polyacetal as its material. For example, its length L is set at 12.67mm, its outside diameter OR on both ends is set at 7.18mm, its inside diameter IR of a shaft hole 20 is set at 1.9mm, its height (h) of protruding stripes 22 is set at 0.01mm and its pitch (p) of the protruding stripes 22 is set at 0.05mm. The primary roller 2 which has been shaped is heat-treated in a furnace e.g. at 130 to 140 deg.C and for three to four hours. Then, the residual strain of the roller 2 is removed and its hardness is increased. After that, the inner circumference of the shaft hole 20 is cut by means of a cutting machine, and the outer circumference is cut by means of another cutting machine. Thereby, a guide roller 1 whose outside diameter is 7.0mm and whose inside diameter of a shaft hole 10 is 2.0mm can be finished. By this cutting operation, a skin layer on the outer circumferential face is removed, and the guide roller 1 whose accuracy is high can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a VTR and a tape recorder.
The present invention relates to a method of manufacturing a guide roller for a magnetic tape used in a magnetic recording / reproducing apparatus such as a recorder.

[0002]

2. Description of the Related Art A method of manufacturing a guide roller for a magnetic tape includes a cutting method and a molding method using a die. In the case of manufacturing by cutting, for example, when finishing a product having an outer diameter of 7 mm, a synthetic resin bar material having an outer diameter of 7.3 to 7.5 mm is cut into product dimensions to form a blank, and this blank is used by a cutting machine. A guide roller is manufactured by cutting with. In the case of manufacturing by molding, for example, FIG.
As described above, a lightening hole 1a having an appropriate shape is simultaneously formed between the outer periphery of the guide roller 1 and the shaft hole 10. This is because the center portion of the guide roller 1 in the longitudinal direction shrinks more than other portions when the lightening hole 1a is not formed, and the outer diameter of this portion becomes smaller than the outer diameter of both end portions. This is because the outer shape of the roller is shaped like a drum as a whole.

[0003]

When the guide roller is manufactured by molding, it can be manufactured at low cost, but high dimensional accuracy (particularly roundness) cannot be obtained. In addition, it is preferable that the guide roller has a certain weight, but as described above, the guide roller needs to have a lightening hole, which makes the weight lighter, and the other parts on the entire surface contacting the mold during molding. There is a drawback that a softer skin layer is formed. Therefore, it cannot be used in high-grade magnetic recording devices. On the other hand, when manufactured by cutting, a relatively high dimensional accuracy can be obtained, but it takes a long time to process, and there is a drawback that the cost of the shaft hole and the amount of meat on the outer periphery are large, resulting in high cost.

An object of the present invention is to provide a method of manufacturing a guide roller for a magnetic tape, which solves the above problems.

[0005]

According to the present invention, a step of forming a primary roller of synthetic resin or other non-magnetic material having an outer diameter slightly larger than a product dimension and a shaft hole diameter slightly smaller, A method of manufacturing a guide roller for a magnetic tape is provided, which comprises a step of cutting and finishing the inner circumference and the outer circumference of the shaft hole of the primary roller. Either cutting of the inner circumference of the shaft hole or cutting of the outer circumference may precede. The primary roller is preferably heat-treated (annealed) before cutting. The heat treatment temperature is lower than the temperature at which the material begins to melt. When the heat treatment temperature is high, the heat treatment time is short, and when the heat treatment temperature is low, the heat treatment time is long. For example, when the material is polyacetal, it is held at 130 to 140 ° C. for 3 to 4 hours. In the step of molding the primary roller,
It is preferable to form a large number of fine grooves or ridges substantially concentric with the shaft hole on the end surface of the primary roller. The groove or ridge can be formed by cutting before or after the cutting step.

[0006]

According to the manufacturing method of the present invention, the primary roller manufactured in the molding step has a slightly drum-like outer shape as described above and has a soft skin layer on the entire surface formed at the time of molding. However, the skin layer on the inner and outer circumferences of the shaft hole is removed by the next cutting step, and the outer shape, which was slightly drum-shaped, is formed into a columnar shape, and the roundness is higher than the roller manufactured by only cutting. Rollers of degree are manufactured. If the heat treatment is performed before the formed primary roller is cut, the roller promotes crystallization of the material to increase hardness and remove residual strain. In the manufacturing method according to the present invention, the guide roller can be manufactured at a very low cost in combination with the fact that the amount of cutting is small as compared with the case of manufacturing only by cutting. A guide roller having a plurality of fine grooves or protrusions concentric with the shaft hole formed or formed on the end surface is a guide roller and a color roller during operation of the equipment.
The friction resistance with the (stopper) becomes small, and the guide roller rotates very smoothly.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the manufacturing method according to the present invention will be described with reference to FIGS. FIG. 1 is a sectional view of a primary roller molded in a molding process, FIG. 2 is a partially enlarged view of an end surface of the primary roller, FIG. 3 is a sectional view of a guide roller after finishing by cutting, and FIG. It is sectional drawing of the tape guide assembled using the guide roller manufactured by the method of this Example.

Using a predetermined mold, for example, a polyacetator
A primary roller 2 as shown in FIG. 1 is molded with a low friction synthetic resin such as a resin. When the primary roller 2 is molded, a large number of fine grooves or ridges 22 are simultaneously molded on the end faces of the projecting portions 21 at both ends of the roller 2 that slightly project as shown in FIG. The primary roller 2 molded in this way is shown in FIG.
The center in the lengthwise direction is slightly constricted due to the contraction in the axial direction, and the whole shape is slightly drum-like. The inner and outer circumferences of the shaft hole 20 and other surfaces have a skin of about several tens of μm. Layer 23
Are formed.

The primary roller 2 of the embodiment shown in FIG. 1 is made of polyacetal and has a length L12.57 mm and outer diameters OR at both ends.
7.18 mm, the inner diameter IR of the shaft hole 20 is 1.9 mm, the height of the ridge 22 is 0.01 mm, and the pitch of the ridge 22 is p0.05 mm.

The primary roller 2 molded as described above,
In the next step, the temperature is held in the furnace at 130 to 140 ° C. for about 3 to 4 hours. This heat treatment removes the residual strain of the primary roller and increases its hardness.

After the above heat treatment, the inner circumference of the shaft hole 20 is cut by a cutting machine, and then the outer circumference is cut by another cutting machine to obtain an outer diameter of 7.0 mm and an inner diameter of the shaft hole 10 of 2.0 mm. Finish the guide roller 1. Since both ends are not cut,
The fine grooves or ridges 22 on the protrusions 21 remain. By this cutting, the skin layers 23 on the inner and outer peripheral surfaces of the primary roller 2 in FIG.
A guide roller 1 having a precision of 0.01 mm or less is manufactured.

The guide roller 1 manufactured as described above
Is rotatably mounted on the shaft 3 as illustrated in FIG. 4, and the stainless steel collars -4 and 5 for positioning the guide roller 1 in the axial direction are press-fitted and fixed to the magnetic tape guide. Make up. A mounting screw 50 for mounting on, for example, a substrate of a device (not shown) is formed at the lower end of the lower collar 5.

According to the manufacturing method of the above embodiment, the cutting time is extremely short and the cutting amount of the material is small as compared with the case where the roller is manufactured by cutting the blank obtained by cutting the bar material. As a result, the guide roller can be manufactured at lower cost than the conventional manufacturing method by cutting. Further, since it is not necessary to form the lightening hole 1a as shown in FIG. 5, it is possible to manufacture a guide roller having a predetermined weight even with a small size, and the precision (roundness of the inner and outer circumferences) can be improved. It is possible to manufacture a guide roller having an accuracy equal to or higher than that of a case where a guide roller is manufactured by cutting a blank obtained by cutting a bar material. Further, since a large number of fine grooves or ridges 22 concentric with the shaft hole are formed on the end surface of the guide roller 1, when the magnetic tape guide is assembled as shown in FIG. The end surface of the guide roller slides well with the collars 4,5, and the guide roller 1 rotates very smoothly.

In the above-described embodiment, concentric fine grooves or ridges 2 are formed on both end faces of the primary roller 2 in the molding process.
Although No. 2 is molded, it may be molded on only one of the end faces, and this groove or protrusion 22 may be formed by cutting before or after the subsequent cutting process instead of the molding process. be able to.

[0015]

According to the method of manufacturing a guide roller according to the present invention, a guide roller having an accuracy higher than or equal to the case of cutting and cutting a bar can be manufactured at a much lower cost. ..

[Brief description of drawings]

FIG. 1 is a sectional view of a primary roller molded in a molding process according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an end portion of the primary roller.

FIG. 3 is a cross-sectional view of a guide roller after finishing the primary roller of FIG. 1 by cutting.

4 is a sectional view of a magnetic tape guide using the guide roller of FIG.

FIG. 5 is an end view of a guide roller manufactured only by molding.

[Explanation of symbols]

 1 Guide Roller 10 Shaft Hole 1a Lightening Hole 2 Primary Roller 20 Shaft Hole of Primary Roller 22 Groove or Protrusion 23 Skin Layer 3 Shaft 4,5 Color 50 Screw L Primary Roller and Finished Length of guide roller OR outer diameter of primary roller IR inner diameter of shaft hole of primary roller or outer diameter of finished guide roller ir inner diameter of shaft hole of finished guide roller

Claims (4)

[Claims] 1. A step of molding a primary roller having a slightly larger outer diameter and a slightly smaller shaft hole diameter than a product size by using a synthetic resin or other non-magnetic material, and an inner circumference of the shaft hole of the primary roller. And a step of cutting and finishing the outer periphery of the guide tape for a magnetic tape. 2. A step of molding a primary roller having a slightly larger outer diameter and a slightly smaller axial hole diameter than a product dimension by using a synthetic resin or other non-magnetic material, and a step of heat-treating the primary roller. And a step of finishing by cutting the inner circumference and the outer circumference of the shaft hole of the primary roller.
Manufacturing method of a guide roller for a pump. 3. The step of forming the primary roller, wherein a plurality of fine grooves or ridges substantially concentric with the shaft hole are formed on the end surface of the primary roller. 1. The method for producing a guide roller for a magnetic tape according to 1 or 2. 4. A plurality of fine grooves or ridges substantially concentric with the shaft hole are cut on the end surface of the roller before or after the cutting and finishing step. Alternatively, the method for producing the guide roller for a magnetic tape according to the item 2 or 3.