Printing Magnetic Saddle

Abstract

A magnetic saddle for use in printing comprising the base plate for saddle consisting of a non-magnetic material and superposed on the printing cylinder, a plurality of yokes arranged at regular intervals on the surface of said base plate lengthwise, and the permanent magnet consisting of a plurality of small blocks of ferromagnetic material, said blocks being arranged between said yokes and conjoined by virtue of the binder consisting of a thermosetting resin and filling the gaps, wherein the base plate, the yoke and the permanent magnet are integrated.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic saddle to be mounted on the printing cylinder of a printing machine and a method of producing the same.

2. Description of the Prior Art

The fitting of a saddle of this type on the printing plate has heretofore been performed by the use of an adhesive tape. Such means of fitting, however, is defective in that it takes too much time not only in fixation of the printing plate, amendment of the position thereof, and so on, but also in removal of the adhering adhesive tape per se and clearing off the adhering remnants after the demounting of said printing plate.

With a view to making up for these defects, a variety of magnetic saddles designed to make the printing plate magnetically fit thereon have already been proposed.

However, such a magnetic saddle as being satisfactory in strength, stiffness and magnetic force concurrently has never been proposed.

In the case of a magnetic saddle composed of sinterred ferrite magnets, for instance, though it admittedly possesses sufficient strength and stiffness, it is defective in that, because of its poor impact resistance, it is apt to be damaged or its edge chipped when dropped by mistake, and, not only that, its production cost becomes too high as it requires a large-sized press.

As to a magnetic saddle composed of a mixture of ferrite and synthetic rubber, synthetic resin or the like, it is defective in that it is difficult not only to produce such one as having a magnetic force of required strength but also to realize and maintain the dimensional accuracy thereof.

In the case of a magnetic saddle wherein an electro-magnet is laid, it is also defective in that it tends to be complicated in structure per se, requires troublesome wiring to supply electricity to the electro-magnet, and calls for special consideration in respect of the safety device to ward off danger involved in the application of electricity.

SUMMARY OF THE INVENTION

The principal object of the present invention is to provide a printing magnetic saddle which makes up for the aforementioned defects of the conventional magnetic saddles and is possessed of less thickness, more strength and stiffness, and a very strong magnetic force, as compared with the latter.

Another object of the present invention is to provide a printing magnetic saddle which makes it possible not only to fix the printing plate magnetically on the saddle by merely placing the former on the latter, but also to perform amendment of the position of the printing plate easily as compared with the conventional saddles.

A further object of the present invention is to provide a printing magnetic saddle which has a base plate consisting of a non-magnetic material, said base plate being so devised that the magnetic line of force emanating from the permanent magnet disposed on its outside leaks to the side of the printing cylinder to thereby prevent the flux density on the surface of the saddle from decreasing and generate a strong magnetic force on said surface.

A still further object of the present invention is to provide a printing magnetic saddle, wherein the base plate consisting of a non-magnetic material is composed of a wound fibrous layer impregnated with a thermosetting resin, said base plate combined with the yoke and the permanent magnet being molded into a whole and imparted with flexibility and elasticity.

Still another object of the present invention is to provide a printing magnetic saddle, wherein the yokes and the small block-shaped magnets are arranged on the base plate consisting of a non-magnetic material along the circumferential direction to maintain the stiffness, and said yokes and magnets are made to adhere firmly and integrally by means of a thermosetting resin on the base plate composed of a fibrous layer impregnated with a thermosetting resin, so that it is free of deformation by the frictional heat arising at the time of use and is possessed of a hardness and mechanical properties enough to cope effectively with the printing pressure.

An additional object of the present invention is to provide a printing magnetic saddle, wherein a coating film of rubber or high molecular substance having a large coefficient of friction is formed on its surface, whereby the printing plate put thereon is prevented from sliding, the surface of the permanent magnet is free from damage, and the yoke is prevented from getting rusty.

Yet another object of the present invention is to provide a printing magnetic saddle, wherein said wound fibrous layer forming the non-magnetic base plate consists of a plurality of inner layers, each inner layer being composed of fibers as wound round the iron core in parallel at a right angle to the axial direction of the iron core, and a plurality of outer layers of fibers as wound round the iron core at a prescribed oblique angle to the axial direction of the iron core, said outer layers consisting of the layer of fibers as wound at said oblique angle clockwise and the layer of fibers as wound at the same oblique angle but anti-clockwise, alternately, and is not only possessed of sufficient flexibility as well as elasticity but also capable of demonstrating an extremely high work accuracy without resorting to delicate internal finishing work.

Still an additional object of the present invention is to provide a printing magnetic saddle, wherein the diameter of the iron core for the prupose of molding a cylindrical material for the saddle is determined to be very slightly smaller than the diameter of the printing cylinder by taking into consideration the fact that said cylindrical material tends to expand outward when split into plural saddles resulting in an enhanced radius of curvature of the saddle, thereby making the saddle fitting for the printing cylinder.

BRIEF DESCRIPTION OF THE DRAWING

Referring to the appended drawings, FIG. 1 is a front view -- as cut in part -- of a magnetic saddle for use in printing according to the present invention.

FIG. 2 is a cross-sectional view of the iron core -- on an enlarged scale -- taken along the line II--II in FIG. 1.

FIG. 3 is a cross-sectional view taken along the line III--III in FIG. 2.

FIG. 4 is a perspective view of the state of the fibrous layer as wound round the iron core.

FIG. 5 is a plan of the yoke with the blocks of permanent magnet arranged thereon.

FIG. 6 is a cross-sectional view taken along the line VI--VI in FIG. 5.

FIG. 7 is a front view of the longitudinal cross-section of the state of a mold at the time of pouring the thermosetting resin therein.

FIG. 8 is a perspective view of a couple of semicylindrical saddles obtained from one cylindrically molded material.

FIG. 9 is a front view of the longitudinal cross-section of another mold applicable in practicing the pouring of the thermosetting resin.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, the numeral reference 1 denotes the printing cylinder, 2 denotes the magnetic saddle according to the present invention as mechanically fitted on said printing cylinder, and 3 denotes the printing plate as magnetically fixed on the surface of said magnetic saddle 2.

In FIGS. 2 and 3 showing the essential part of said magnetic saddle 2 on an enlarged scale, the numeral reference 4 denotes the non-magnetic arcuate base plate composed of fibrous layer impregnated with a thermosetting resin, and 5 denotes the yoke having a high magnetic permeability which consists of soft iron, Ni-Mo-Fe alloy, Mn-Zn ferrite, Ni-Zn ferrite, Ni-Zn-Co ferrite and the like and is provided with the block-shaped magnets 6 disposed on the surface of its one side at regular intervals along the circumferential direction. Accordingly, the yokes 5 and the magnets 6 are disposed alternately along the axial length of the base plate 4. On this occasion, the magnets 6 are disposed in such a fashion that the confronting sides of the neighboring magnets 6 along the length of the axial base plate 4 are of the same polarity and repel each other. The top side of the magnet 6 is inside the circumference of the yoke 5, and the gap between the top side of the magnet and the outer circumference of the yoke as well as the gap between the circumferentially spaced magnets are filled with the thermosetting resin 7, whereby these members are firmly conjoined. In FIG. 2, M denotes the magnetic lines of force.

Hereunder will be described the method of producing the foregoing magnetic saddle by reference to FIG. 4 and those that follow.

Referring to FIG. 4, a glass fiber having the glass content of 75 .about. 80 percent and impregnated with a thermosetting resin such as expoxy resin and the like is wound round the iron core 8 -- which is smaller in diameter than the printing cylinder by 0.2 .about. 0.6 percent -- in parallel at a right angles to the axial direction of the iron core 8 in the beginning. Subsequently, the same glass fiber is wound round the same iron core 8 in clockwise spiral fashion at a prescribed oblique angle to the axial direction of said core to form a layer of spirally wound glass fiber and next in anti-clockwise spiral fashion at said prescribed angle to the axial direction of said core to form another layer of spirally wound glass fiber. Upon obtaining a fibrous layer of a prescribed thickness by repeatedly forming the foregoing two types of layers of glass fiber wound spirally in the opposite directions alternately, said fibrous layer is heated to harden the component resin and then its external surface is subjected to grinding work to be made into the cylindrical member 9 of about 3 mm thick. Thereafter, the cylindrical member 9 is released from the iron core 8.

FIGS. 5 and 6 show the yoke with magnets: that is, the ring-shaped yoke 5 of less than 2 mm thick made of soft iron is provided with a plurality of block-shaped magnets 6 of 5 .about. 15 mm thick each as fixed on its one side with an adhesive at regular spaced intervals along the circumferential direction.

FIG. 7 shows a mode of fixing the yoke with magnets on the surface of the aforesaid cylindrical member 9: that is, the cylindrical member 9 is put erect on the base plate 10; after applying adhesive to the surface of the cylindrical member 9, the yoke 5 with magnets is fitted on the cylindrical member 9 by its central hole one after another; when the pile of yokes 5 attain a prescribed height, the cylindrical outer mold 11 having an inside diameter slightly larger than the outside diameter of the yoke 5 is fitted on said pile; a colored thermosetting resin, such as epoxy resin, as mixed with 20 .about. 50 percent of a filler is poured into the thus set outer mold 11; the resin is hardened by applying heat; and thereafter the outer mold 11 and the base plate 10 are removed.

Next, after grinding the external surface of the product to attain the prescribed measurements, by cutting said product with a metal saw and the like as shown in FIG. 8, a plural number of saddles 2 are obtained.

Hereunder will be given an example embodying the present invention by reference to FIG. 9.

EXAMPLE

A glass roving (GYR-60 PWE) made by Nitto Bo K.K. as subjected to dipping in an epoxy resin (CIBA GY 250)/acid anhydride (HHPA: hexa-hydrophthalic anhydride) was wound around the iron core 8 measuring 325.35 mm (outside diameter) .times. 500 mm (length) by means of a filament winding machine in such a fashion that first winding the glass roving in parallel at a right angle to the axial direction of the iron core 8 to form 2 .about. 3 layers consisting of said glass roving, thereafter winding clockwise in parallel at a prescribed oblique angle to said axial direction to form a layer of said glass roving on the foregoing layers, next winding anticlockwise in parallel at the same oblique angle to form another layer of the glass roving, and repeatedly forming the above two types of layer of glass roving wound spirally in the opposite directions alternately, whereby the cylindrical member 9 composed of wound multilayers of glass roving was formed. After hardening this cylindrical member 9 by heating at 120.degree.C for 3 hours, its surface was subjected to grinding to attain the diameter of 331 mm.

Subsequently, said cylindrical member 9 was put erect on the base plate 12, the washer 13 was fitted on the cylindrical member 9, the anisotropic sinterred ferrite blocks 6 measuring 7 mm (t) .times. 4 mm (w) .times. 20 mm (l) each (See FIGS. 5 and 6) were arranged on the surface of said washer 13 along the circumferential direction, the yokes 5 made of soft iron and measuring 350 mm (outside diameter) .times. 332 mm (inside diameter) .times. 1 mm (thickness) each were put on said ferrite blocks by fitting on the cylindrical member 9, said ferrite blocks 6 arranged as above and the yokes 5 being piled up alternately to attain 400 mm in height, and the washer 14 was put on the top of the pile. On this occasion, the yoke 5, the ferrite blocks 6 and the cylindrical member 9 were conjoined with an epoxy adhesive (CIBA GY-252/A-155/H4) at the room temperature.

Next, the cylindrical outer mold 15 having the inside diameter slightly larger than the outside diameter of the yoke 5 was fitted to the exterior of the structure built as above, and then a liquid epoxy resin (CIBA GY-252) mixed with a coloring agent and a filler was poured into it from its top so as to fill all the gaps, hardened at the room temperature, and thereafter completely hardened by 12 hours' after-cure at 60.degree.C.

Subsequent to the curing, after removing the base plate 12 and the outer mold 15, the structure was subjected to grinding to attain 346.13 .+-. 0.02 mm in outside diameter, then cut into a couple of semicylindrical segments with a metal saw and the like and released from the iron core, whereby the magnetic saddles of about 10 mm thick for use in printing newspapers were obtained. It is preferred that the surface of saddles according to the present invention have applied thereto a coating film less than 1/10 mm in thickness of rubber or synthetic resin and having a coefficient of friction not less than 0.4. Thus, the saddles of the present example were next coated with urethane resin having the static friction coefficient of 0.65 to attain 0.06 mm in thickness.

A magnetic saddle for use in printing newspapers is generally required to be possessed of a thickness accuracy of .+-. 2/100 mm and the mangetic flux density of more than 1,000 gauss.

The magnetic saddle produced as above according to the present invention proved to have the thickness accuracy of 1.5/100 mm and the magnetic flux density of 1,500 gauss.

Claims

What is claimed is:

1. A magnetic saddle for use in printing which comprises an arcuate and substantially semicylindrical non-magnetic base plate having fibrous layers impregnated with a thermosetting resin, wherein said base plate comprises a plurality of layers of wound fibers including at least one radially inner layer of circumferentially extending fibers and a plurality of outer layers of fibers extending at an oblique angle to the circumference of said base plate, said outer layers alternatingly having fibers angled toward one axial end and toward the other axial end, respectively, of the base plate, said base plate having an outer surface, a plurality of arcuate yokes spaced longitudinally at regular intervals along said outer surface of said base plate and extending circumferentially thereof, said yokes and said base plate being of equal arcuate extent, a plurality of small magnets disposed in the space between adjacent yokes and being spaced circumferentially at regular intervals on the outer surface of the base plate and along each yoke, said magnets being of substantially lesser circumferential extent than the yokes, and a continuous mass of thermosetting resin disposed in the gaps between the magnets and defined by the base plate and yokes to thereby conjoin the foregoing constituent elements.

2. A magnetic saddle for use in printing as defined in claim 1, including a coating film applied to the surface of said saddle, said coating film consisting of rubber or synthetic resin.

3. A magnetic saddle according to claim 2 in which the thickness of said coating film is less than 1/10 mm, said film having a coefficient of friction not less than 0.4.

4. A magnetic saddle according to claim 3 wherein said coating film is of urethane resin having a static friction coefficient of about 0.65 and a thickness of about 0.06 mm.

5. A magnetic saddle according to claim 1 wherein each yoke comprises a circumferentially elongate element fixedly secured to the outer surface of said semicylindrical base plate and extending radially outwardly therefrom beyond said magnets.

6. A magnetic saddle according to claim 5 wherein said thermosetting resin disposed in the gaps between the magnets extends radially beyond said magnets to the radially outer edges of said yokes, thereby to define an arcuate resin band axially between and fixed to each adjacent yoke pair and circumferentially coextensive therewith.

7. A magnetic saddle according to claim 1 wherein the circumferential extent of said arcuate base plate and each of the yokes is substantially half a circle, the set of magnets between a given pair of yokes extending in an arcuate manner substantially through a half circle.

8. A magnetic saddle according to claim 1, wherein the plurality of magnets, as disposed lengthwise of said base plate, are positioned with their sides of the same polarity confronting one another so that the plurality of magnets repel one another in the lengthwise direction of said base plate.