JPS5848267A - Production of guide cylinder - Google Patents

Abstract

PURPOSE:To obtain a highly precise cylinder with high productivity, by forming a spiral groove to the inner surface of the ring body obtained by cutting a cylindrical body produced by the plastic working to unify the ring body with the internal molded body and then cutting the outer circumference of the ring body to form a tape guide surface. CONSTITUTION:A molded cylindrical body produced by the plastic working is cut in accordance with the heights of upper and lower cylinders to obtain ring bodies 1a and 1b. A spiral groove S is formed to the inner surface of each of the bodies 1a and 1b, and a molten material having an approximately equal heat expansion coefficient as the ring body is flowed into the bodies 1a and 1b. Thus the internal molded bodies are unified with the bodies 1a and 1b via the groove S without any play to obtain upper and lower cylinders 2 and 3. The outer circumferences of the cylinders 2 and 3 are cut to form tape guide surfaces 2a and 2b. Then the cylinders 2 and 3 are connected with a socket 4. Thus a cylinder of a VTR, etc. containing the ring body and the internal molded body unified with no play can be produced with high precision and high productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a cylinder for a video tape recorder with excellent productivity.

Die-casting is one method of molding metal.

This method (1) is a method in which molten metal is injected into a mold under high pressure, and the molding time is short and no special technology is required.
It is used for various molding.

However, in the molded product using this molding method, nests of air bubbles and hard spots composed of impurities due to aluminum oxidation are formed.

When molding the guide cylinder that forms the tape guide surface using the aluminum die-casting method.

Holes were formed on the guide surface of the tip, and the inner surface of the bar could not be formed smoothly, and the tip of the bar was damaged due to hard spots.

Therefore, guide cylinders have conventionally been molded by casting methods or molten metal forging methods, which have low productivity.

Even with these methods, cavities and hard spots could not be completely eliminated, and the occurrence of defective products could not be avoided.

The drawing method is a method for forming metal at low cost without forming cavities or hard spots.

However, in this method, the molten metal before solidification is drawn out from a die and molded into a columnar or cylindrical body, and the cross section of the molded product is limited to a regular shape that matches the shape of the die.

Therefore, the guide cylinder cannot be directly extracted and processed.

Therefore, a method of constructing a guide cylinder by molding the internal molded body of the ring body to use it as a tape guide surface is considered, but the material for making the guide cylinder is Because aluminum shrinks as it solidifies.

This cannot be expected, and this gap causes play in both the same direction and the axial direction on the guide surface, which becomes a major obstacle for guide cylinders that require high precision.

Therefore, one purpose of the present invention is to eliminate the backlash.

We propose a new and effective guide cylinder manufacturing method that eliminates gutter in the axial direction of the internal molded body using the screw groove and eliminates looseness in the same direction using the through hole when the internal molded body is solidified by injecting the body. This is what I am trying to do.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below according to an illustrative embodiment. In this embodiment, an upper guide cylinder and a lower guide cylinder are fixed oppositely by a connector to form a tape guide surface, and a pair of rotary heads protrudes slightly from the opposing gap between the two guide cylinders.

The present invention is applied to a guide cylinder that performs recording and reproduction by scanning the tape surface.

First, in this embodiment, a cylindrical body is formed by drawing.

This molded body has a wall thickness of 5mm and a predetermined outer diameter, and is cut into a number of upper ring bodies (1a) and lower ring bodies (1b) according to the heights of the upper guide cylinder and lower guide cylinder. be done. A screw groove (SL) is formed on the inner surface of both the rings (1a) and (1b) using a cutting tool, and a through hole (In) is drilled from the outside of J. The order of the tightening groove formation and through hole drilling process does not matter. When the molten aluminum that penetrates into the through hole (m) solidifies and becomes an internal molded body, the ring body (1&) (1b) and the internal molded body will play in the same direction and in the axial direction. Upper guide cylinder (
2) and configures the lower guide cylinder 131. after that.

The ring body (1m) (1b) was subjected to a heat treatment (52 (1:8 to 10 hours)) to homogenize the alkali electrocrystals and encapsulate impurities, and a heat treatment for a predetermined time to precipitate the silicon component. By this process.

The structure of the rings (1m) (1b) is stabilized, and the Ip friction ratio is also reduced. The upper guide cylinder (2) is formed by integrating the internal molded body by cutting the upper ring body (1) with a cutting tool to form a tape guide surface (2a). In addition, the lower guide cylinder (31 is also lower! Ring body (1
b) is processed by a cutting tool to form the tape guide surface (3a) and the diagonal tape guide edges and grooves (5b).Then, the upper guide cylinder (2) and the lower guide cylinder (31) are opposed to each other by the connector (4). If it is fixed and is provided with a rotary head (not shown) that is rotatable through the opposing gap, it is possible to produce an idle cylinder assembly with high productivity.

In the embodiment described above, the present invention is applied to a fixed type guide cylinder, but the present invention can also be applied to a one-rotation type guide cylinder. Moreover, 1. It goes without saying that the present invention may be adopted as one of the upper and lower guide cylinders as necessary. Furthermore, the ring body of this example was made of a material mainly composed of aluminum with a predetermined amount of silicon mixed in, and the internal molded body was made of aluminum, but Ikusei Uchi! - Various metals and synthetic resins can be used as the material. However, it is preferable to use a material having the same coefficient of thermal expansion as that of the ring.

Therefore, according to the present invention, since the internal molded body is firmly integrated into one body by the screw groove and the through hole, the shape of the guide cylinder can be stabilized with high accuracy, and the effect is large.

[Brief explanation of the drawing]

The figure shows an exploded sectional view of a guide cylinder employing the present invention. Explanation of main drawing numbers (1m), (j b,)... ring, (2 b 3 to
・Guide cylinder. (m-...through hole, (8N...screw groove, <2&)C5m
)−・−Tape guide surface. Procedural amendment (spontaneous) October 5, 1975 Commissioner of the Japan Patent Office 1. Indication of the case Patent application dated September 16, 1980 (6) 2. Name of the invention Guide cylinder manufacturing method & Person making the amendment Patent applicant Address: 2-18 Keihan Hondori, Moriguchi City. Name (188) Sanyo Kamiki Co., Ltd. Representative: Kaoru Iue 4, Agent address: 2-18-5 Keihan Hondori, Moriguchi City, “Claims” and “Detailed Description of the Invention” of the specification subject to amendment
column. 6. Contents of amendment 411 The scope of claims has been amended as shown in the attached sheet. (2) "Drawing method" stated on page 2, line 14 of the specification has been corrected to "plastic processing such as extrusion or drawing". "By pushing out or pulling out" is corrected to "pull out or pull out.""Drawingprocessing" in the bibliography on page 4, line 3 has been amended to "extrusion processing".

Claims (1)

[Claims] (1. Form a screw groove in l!1fjJ of the ring body obtained by cutting an a!-shaped cylindrical body by drawing process, and inject a through-hole joint shaft body to integrally mold an internal molded body inside the ring body, A method for manufacturing a guide cylinder, characterized in that a tape guide surface is formed by cutting the circumferential surface of the ring body.