US1778125A - Stereotype mat - Google Patents

Description

Patented o r, 14,-1930 ETD A'T'Es ARI-IE W. SCHORGER, OF -MADISON, WISCONSIN, ASSIGNOR TO G. F. BURGESS LABORA- TORIES, INQ, 01EMADISON,-WISCOI TSI1\T, A CORPORATION OF DELAWARE PATENT OFFICE s'rnanoryrn MAT No Drawing.

7 This invention relates to an improvement in sterotype mats and especially the so-called' dry mats of commerce.

; Stereotype mats and especially dry mats consist of a heavyfibrous sheet, usually comprising chemical wood pulp, and containing suitable fillers. Such a .mat and the method of making is described in United States Patent No. 1,524,155. Thesesheets usually vary from 0.028 inch to 0.036 inch in thickness. Their physical characteristics may vary from soft to hard depending upon the requirements of the user. A facing material or coating may be applied to the surface of the mat that comes in contact with the type and stereotype metal to improve the release of the hot metal and improve the qualityof the printing.

A stereotype mat for newspaper work is used in the following manner. As soon as a form containing the type has been set up, a stereotype mat is superimposed, then covered with blankets or felts and passed through a rolling machine, whereby the mat acquires a reverse impression of the type. The mat 'after drying .is placed in a casting machine where it is held in the form of a cylinder. Molten stereotype metal is then poured into the machine whereby a stereotype plate in the form of a metal cylinder is obtained containing on its surface an exact duplicate of the type in the original flat form.

The stereotype plate is then placed in a cylinder press whereby papers can be printed at high speed. Several casts can be made easily and rapidly from the same mat so that a number of presses can be placed in operation almost simultaneously.

A dry mat is not used in the dry state. It is first placed in a humidor where it takes up from 10 to 30 per cent moisture. It is then rolled on a form, removed, placed in a cylindrical scorcher where most of the moisture is removed in one or two minutes. When the hot stereotype metal strikes the impressed 7 scorched surface practically all of the balance of the moisture is driven out of the mat. As a result of such strenuous treatments various troubles are encountered. It is the object of my invention to overcome or minimize these troubles.

Application filed April 26, 1929. Serial No. 358,424.

heretofore encountered in its use, disappear.

These punctures should not cut the fibers but merely push'them aside during the piercing operation; hence the strength of the mat is not affected materially. I have found that a mat punctured to within 0.006 ofthe face of the mat gives excellent results. It is preferable to have the holes spaced apart not more than in each direction. This spacing can be advantageously much less, giving ex cellent results. The exact spacing and depth of puncture will vary with the type of mat and service to which it is to be put. Puncturing the mat in this manner results in several advantages over mats heretofore used. These advantages are: i

1. 1 The mat can be scorched (dried) more quickly;

2. The formation of steam pockets by blistering is prevented;

3. Relief'of stresses in the mat, and consequent reduction, if not'elimination, of buckling is obtained;

4. Increased flexibility is obtained;

5. Chilling in the sterotyped plates is reduced.

The above mentioned advantages will be ance to the escape of the steam, and this may a result in splitting the mat or producing blisters. Steam can escape in the longitudinal direction ofthe mat, that is in the fiber direction, more easily than it can perpendicularly. As a result of the perforations inch apart, it is not necessary for the steam to travel more than inch before it has an 2. Blistering occurs most frequently on.

cuts representing objects. A large continuous area of the mat repre'"s ei'ited bythe cutisa compressed greatly, frequently to one-half the original thicknessofthe heat. The moisture leaves" this area much more slowly during' scorching than other" parts of themat. If the cuts retain some moisture due to incomplete drying, blisters will be formed when the hot stereotype metal is poured againstthem. The perforations help eliminate this difficulty to a verygreat extent.

3. Buckling may be largely eliminated through release or'avoidance of stressesin the All mats, particularly the dense type, have certain stresses produced'in the course of manufacture. The more frequent causeo'f stresses and buckling, is uneven drying; If a'portionofthe mat dries readily it will become se't as soon as allthe moisture has escaped; As" a result the parts drying subsequently cause" high tension and result inbuckling'l" Q 4. Perforation ofthe mats produces'acer I i:

tain"flexibility that permits better molding.

5. Perforation of the mat prevents chilling by permitting a'ir and ste'am to escape The face of a chilled plate has", ripple marks as" though throughrthe back of the mat;

caused by ther'ushof air or steam through the molten metal. ture may chill the casting, but trouble'is' seldom encountered except on cuts where the mat is very dense. Whenthe molten metal is poured into'jthe box, air; and steam must escape to a certain 'eXtent'through' the mat,

though mostis forced out at the top. The" minute points in cuts may entra'p both air and steam and cause blowing unlessthey do escape through'the mat.;-

"I claim:

1'. A'stereotype mat havin'gamultiplicity of punctures exten'dingfrom'theback-thereof toward the surface of themat- 2. A stereotype mat having afmultiplicity of punctures in the back thereof, most of said punctures extending to within at least 0.006

inch of'the opposite face ofsaidmat;

3. v A stereotype mat having a multiplicity of punctures in the'backthereof but not extending. throughsaid'mat, said punctures be mg spaced not more than g" apart.

4'. A faced'stereotype mat having a mulas per- Any mat retaining moistiplicity of punctures in the back thereof, most of said punctures extendingto within at least 0.006 inch of the facing and said punctures being spaced not more than 1 g apart. v

a 5. The step in the method ofventing steam from the back of; stereotype mats? during the casting operation which eamprises" piercing 't'heba'c'ks of said mats with a multiplicity of punctures deep en ough to approachathe'ca'sta ingfaceof,;said mat.i-

In testimony whereof I affix my signature. ARLIE W. SCHORGER.