KR20010043214A - Insert molded end pin shafts for magnet roll developer - Google Patents

Abstract

The present invention relates to a developer magnet roll 1 having end shafts 2 inserted at both ends. The end pin shaft is insert molded in a ferrite and binder magnet roll so that the end pin shaft provides improved strength, improved straightness, and cost savings.

Description

Insert molded end pin shaft for magnetic roll developer {INSERT MOLDED END PIN SHAFTS FOR MAGNET ROLL DEVELOPER}

In general, the magnetic pole pattern contained within the magnet core consists of four or more alternating N-S poles (North-South) formed in a longitudinal direction along the cylinder, similar to the pattern of a four leaf clover as viewed from the end. The core is supported in a developing sleeve framework through an end shaft, which is an important component of the developer magnet roll.

Generally, a developer magnet roll composed of ferrite and a binder is formed by the following method.

If the binder is a ductile flexible thermoplastic material such as extruded polyvinyl chloride (PVC), the magnet is usually assembled on a cold rolled steel shaft for strength, magnetized in the longitudinal direction during the extrusion process, and It is then demagnetized and finally magnetized back to the final pole configuration by an electromagnet after assembly. This process is inherently expensive because of the number of processing steps consisting of extruding the magnetic mixture, adhering the soft and flexible magnet to the shaft, and magnetizing the developer magnet in the final desired pattern.

Alternatively, the strong metal shaft is insert molded into a ductile flexible thermoplastic material, such as ferrite and ethylene vinyl acetate (EVA) binder, to form a developer magnet roll having magnetization made by a permanent magnet or electromagnet in the mold. .

If the binder is a rigid thermoplastic nylon, then the magnet is generally 100% molded to include a small diameter end mounting means. Roll magnets using nylon binders are magnetized by using permanent magnets during molding, or by using electromagnetic coils in the mold to partially magnetize the rolls by the final magnetization that occurs after molding. Nylon binder magnets have good performance and are inexpensive, but when the ratio of weight to length and / or magnet diameter to mounting diameter is large, the end shafts are fragile and easily broken. If the end shaft diameter is increased for increased strength, good performance is obtained as a result. However, the mounting diameter is limited in many applications because of the need for proper geometry between the surrounding geometry and adjacent elements, such as the inner diameter of the developer sleeve end plug from which the end shaft protrudes. In order to have good magnetic performance, the finished magnet roll should be straightened with a minimum circular protrusion.

Many patents on magnet design and magnet production have been registered. The following patent relates to a unique shaft design.

U.S. Patent No. 4,557,582 describes a planar attachment of a magnetic strip to a support shaft of a non-circular cross-sectional asymmetric polygonal shape, in order to attach the support shaft to a cartridge, the support shaft is at least With an end portion shaped in this manner. The adhesive bonds the magnetic strip to the central shaft. Magnetic strips, when made separately, are difficult to assemble with each other in an envelope of a long cylindrical shape, and the shaft provides a mechanical mounting method.

US Pat. No. 4,580,121 describes a ferrite magnet having a rubber binder fixed on an extruded aluminum shaft having a plurality of ribs and bonded to each other using a heating tube treatment. The extruded nonmagnetic aluminum shaft provides a vehicle for mounting a strip magnet.

U.S. Pat.No. 4,604,042 discloses that a rare earth permanent magnet in a length-mold larger than its diameter may be placed in a (nylon) ferrite magnet that has a fixed central shaft to compensate for a non-greater than 5 that magnetizes the final cylindrical magnet roll. The insert molding method will be described.

US Pat. No. 4,872,418 describes a ferrite magnet with a nylon binder comprising a cross section flat drive or longitudinal end polygon protrusion at each end.

US Pat. No. 4,954,800 describes the use of electromagnetic magnetization of a roll magnet during molding to achieve a long pole. The resulting roll magnet generally has only two poles, which are then demagnetized and then magnetized back to four poles in the final configuration. This shows an alternative way of performing the final magnetization. The shaft is also an important component with roll magnets.

US Pat. No. 5,319,337 describes a shaft that is insert molded into a magnet roll which also acts as a sleeve. The metal magnetic shaft is preheated and thermally bonded with the thermoplastic resin using a thin adhesive layer. There are a large number of 50 poles on the face, and the magnetic shafts provide important magnetic paths when forming the face poles.

U. S. Patent No. 5,682, 587 describes a universal hollow magnet with a metal filled resin bearing of another structure having a unique end shaft shape similar to a D-shape or square. This support bearing is described as a conical end support member that can also make electrical contact with the bias voltage of the cartridge. End shafts perform a variety of uses, including supports, precision bearing surfaces, and electrical contact points.

U. S. Patent No. 3,149, 403 relates to a stub shaft inserted or insert molded into a non-magnetic core or body to which a magnetic module is consequently attached. In summary, the magnet body is a complex structure of magnetic and nonmagnetic elements.

U. S. Patent No. 4,142, 218 relates to a magnetic roll made of a composite structure consisting of a non-magnetic body and an end hub or of a non-thick body with an end hub, wherein the end hub has a longitudinal magnetic insert added thereto. , A magnetic roll made of a composite structure having an end hub, after which the end shaft is inserted after molding of the body / hub.

U. S. Patent No. 5,583, 473 discloses one shaft end molded in an important configuration as part of a magnet roll body, and a second end shaft pressed and tightly fitted through the molding of the body or the first end.

The present invention relates to electrophotographic, and more particularly to a developer magnet roll for electrophotographic. Generally, the developer magnet roll consists of strontium ferrite in a nylon binder and is formed into a cylindrical shape that acts in an enclosing cylindrical developing sleeve.

1 is a longitudinal cross-sectional view showing a magnet roll according to the present invention;

It is an object of the present invention to provide a developer roll magnet having improved strength compared to one molded magnet which essentially has an end shaft.

It is another object of the present invention to provide a developer magnet roll with improved straightness.

Another object of the present invention is to provide an alternative to the developer roll magnet with a lower cost compared to a magnet using a through shaft.

Another object of the present invention is to provide an improved developer magnet roll having an insert molded end pin shaft for processing benefits for a particular production method.

It is another object of the present invention to provide an improved developer magnet roll having an insert molded non-magnetic end pin shaft for processing benefit for a particular production method.

According to the present invention there is provided an improved developer magnet roll for use in an electrophotographic developer sleeve.

The production of developer magnet rolls, in particular developer magnet rolls with a high overall magnet diameter ratio relative to the support shaft diameter, is achieved by a process with greatly improved roll strength, straightness, processing, and cost.

The invention will be described in detail with reference to the accompanying drawings.

1, in the manufacture of the developer magnet roll 5, there is provided a magnet body roll 1 composed of a particulate ferrite material such as strontium ferrite and a binder and an end pin shaft 2 attached to the magnet body roll. . The end pin shafts are made of metal, ceramic, or plastic. The end pin shaft 2 is inserted into the mold, and the magnet body roll 2 is formed during the standard injection molding process (ie by injecting ferrite particles into the molten binder which are completely mixed in the binder). Typical binders for ferrite are rigid thermoplastic materials such as nylon 6 or nylon 12.

Through the engagement of the insert molded end shafts, the injection molded developer magnet rolls show improved strength, improved straightness, improved process and cost savings, especially with a large ratio of total magnet diameter to support shaft diameter.

A preferred embodiment of the present invention uses a nonmagnetic material, such as the nonmagnetic degree of stainless steel, as the end shaft. This embodiment is preferred when an injection molding machine comprising a permanent magnet is used to produce the magnetic roll. The part into which the shaft 2 is inserted is made of rough tissue (to be rough) to ensure physical locking. Faces that add the most anchoring, such as machined recesses, are another alternative.

The present invention has been described with reference to the structures disclosed herein, and the invention is not limited to the illustrated detailed description, and the application of the invention is such a change or modification as may be within the scope or spirit of the following claims. It is intended to include.

Claims (5)

A developer magnet roll comprising an end pin shaft that is insert molded during roll formation. 2. The developer magnet roll of claim 1 wherein the magnetic body roll is comprised of ferrite particles magnetizable in a binder of nylon. The developer magnet roll of claim 1, wherein the end pin shaft is made of a metal, ceramic, or plastic material. In the manufacturing method of the developer magnetic roll provided with the end pin shaft as described in Claim 1, A manufacturing method of a developer magnetic roll having an end pin shaft for insert-molding said end pin shaft at both ends. In the manufacturing method of the developer magnetic roll provided with the end pin shaft as described in Claim 1, And the end pin shaft is nonmagnetic and has an end pin shaft inserted in an injection mold comprising a permanent magnet.