JPS58173663A - Type disk for typewriter, etc. and manufacture of type disk for typewriter, etc. - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The object of the invention is a method for manufacturing a type desk for a typewriter or the like and a type desk for a typewriter or the like according to the prerequisite concept of claim 1. High demands are placed on this type of type desk. The requirement is, on the one hand, that the material must have sufficient elasticity to retain the necessary deformation without breaking during the printing process. On the other hand, the letters in particular must have a hardness that ensures their constancy of shape even under many impacts.

According to DE 2818861, a method is known in which the injection process is carried out radially outward from the boss. This known method has the disadvantage that air entrapment (small air bubbles) at the free ends of the spokes on which the letters are arranged is not avoided. Furthermore, the pressure of the molding compound generally decreases the further the spoke end is from the injection opening.

The object of the invention is therefore to ensure that characters are formed accurately on the one hand;
and on the other hand to create a method to ensure that said air entrapment does not occur.

For this purpose, the method according to the features of claim 1 is suitable. In this method, a ring is first formed by the synthetic resin material from the injection port, the molding material circulates through the type desk 7 towards both sides of the conduit, and then passes through the injection projection to the center of the boss to the individual spoke tubes. It is formed by flowing into the tract. As a result, during the formation of the spokes, first of all the letters and the centering wedges provided in the forming tool are formed. As a result, the inward air confinement is compressed and, due to the thick dimensions of the boss formed therein, no longer acts as a nuisance on the spokes.

Research has been done to form substantially hard characters that have a long life. The ring can be separated from the type disk which has been pulled out of the forming tool by means of a relatively simply formed cutting tool.

The ring material is subjected to the following processing.

It is expedient to form the ring as described in claim 2. This results in rapid material distribution inside the ring.

Furthermore, the molding material enters the individual molding channels of the spokes under high pressure. Forming the molding tool in such a way that the type desk is obtained by the features of claim 4 has the advantage that the side of the spoke with the letters is avoided from any return condition of the injection projection.

According to the state of the art, for example, DE 24 52 843 A1, it is known to provide the ring with a metal type and to separate the ring after pressing the type onto the spokes. However, this configuration is only suitable for types that can be manufactured from metal.

Embodiments of the present invention will be described based on the drawings.

The type desk 1 has a boss 2 from which emerges radial outwardly directed spokes 3 which have a letter 4 at their free end.

There is a metal ring 5 in the center of the boss 2, through which the type desk 1 can be fitted onto one shaft. In the usual manner, such type desks are provided with a driving opening 6 through which a driving pin passes in order to achieve a non-rotatable connection between the shaft and the type desk. Reference numeral 7 indicates an injection port, and the injection port corresponds to a conduit in the forming tool. 8 is a ring, and the ring is formed by the open molding material from the injection process circulating through the type desk in the directions of arrows A and B, and both material flows occur in the upper region indicated by C in the figure. The molding material is then directed from the radial outside to the inside over the formation of the injection projection 9, with the molding tool first pressing the letter and at the same time the centering wedge, designated 10 in FIG. 2, on the back side of the spoke. It is formed. If necessary, the air contained in the forming tool can be removed from the boss 2 by this manufacturing method.
It is clear that the force is compressed in the center of the force; It is clear that the injection pressure in the region of character 4 is higher than in the region of boss 2. Correct formation of the characters is thereby ensured.

After forming the type disk I with the ring 8, the separation of the ring 8 from the spokes 3 is carried out approximately in the area of the plane indicated by the dash-dotted line using a cutting tool. Type desk 1 is then available for use.

Type the cross section of ring 8 to 10 to 1 of the cross section of spokes.
It was purposefully chosen to correspond to a factor of 2. It makes sense if the ring 8 has a height H greater than the thickness S of the boss 2.

In order to increase the injection pressure at the later free end of the spoke 3 during material flow, it is advantageous to design the injection projection 9 in a conical cross-section. However, it is expedient to design the injection projection 9 in such a way that on the side with the letter 4 it forms a surface 11 lying flush with the surface 12 of the spoke 3.

The conical shape of the injection projection 9 has the advantage that an increased injection pressure occurs during the formation of the character 4. Furthermore, a small cutting force is sufficient at the point where the separation of the spokes 3 takes place. Damage to the type desk 1, spokes 3 or letters 4 is thereby excluded.

[Brief explanation of the drawing]

FIG. 1 shows a top view of the type desk with spokes partially shown, and FIG. 2 shows an enlarged cross-sectional view of the spokes and the ring connected to the type disk. Code in the diagram 1 Type desk 2 Boss 3 Spoke 8 Ring

Claims (4)

[Claims] (1) A method for manufacturing a type desk with radial spokes for a typewriter or the like directed outward from a boss and having characters at its free end, the type desk being manufactured by an injection molding method using a molding tool. In a possible method, the molding material first flows around the specific type disk (1) in the ring (8) and then in the spokes (
3) from the end which becomes the free end towards the center of the boss (2), and characterized in that the ring (8) can be separated from the type desk (1) by means of a cutting tool in a subsequent working step. A method of manufacturing a type desk. 2. A method for manufacturing a type desk according to claim 1, wherein the separated rings (8) have a cross section approximately 10 to 12 times larger than the cross section of the spokes (3). (3) a type desk with radial spokes for typewriters etc. directed outward from the boss and having letters at its free ends, the separated ring (8) being a cross section of the spokes (3); 9. A type desk characterized in that the thickness of the boss (2) is approximately 10 to 12 times larger, and the boss (2) has a height H) that is larger than the thickness S). (4) The injection projection (9) between the ring (8) and the spokes (3) lies flush with its surface (12) on the side on which the empty letter (4) is arranged on the spoke (3). , a type desk according to claim 3.