US2492348A

US2492348A - Matrix drier and shrinker

Info

Publication number: US2492348A
Application number: US662241A
Authority: US
Inventors: Craig C Baker
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-04-15
Filing date: 1946-04-15
Publication date: 1949-12-27
Anticipated expiration: 1966-12-27

Description

Dec. 27, 1949 QC, BAKER 2,492,348

MATRIX DRIER AND SHRINKER 5 Sheets-Sheet 1 Filed April l5, 1946 BY l Dec. 27, 1949 c. c. BAKER MATRIX DRIER AND SHRINKER Filed April l5, 1946 3 Sheets-Sheet 2 INVENTOR. CRAIG C BAKER Illll HHH Illllm l v AT TORNEY Dec. 27, 1949 C, C, BAKER 2,492,348

MATRIX DRIER AND SHRINKER Filed April 15, 1946 3 Sheets-Sheet 3 27 23 25 23 2| 22 L/ l'lll l I7 2 1 2o la 6 s l INVENTOR CRAG C BAKER ATTORNEY Patented Dec. 27, 1949 UNITED STATES PATENT OFFICE MATRIX DRIER AND SHRINKER Craig C. Baker, Los Angeles, Calif.

Application April 15, 1946, Serial No. 662,241

4 Claims.

This invention relates to the drying of moist matrices in preparation lfor their use as molds for the casting of stereotype plates for rotary printing presses, especially newspaper presses.

More particularly this invention relates to that class of@ machines commonly known as vacuum formers'or driers in which the matrix or mat is held by vacuum against a curved iirm surface and subjected to drying heat.

It is desirable to obtain the maximum amount of shrinkage in the matrix during the drying and forming of the same, for the shrinking o the matrix, or condensing of the mat, reduces the size of the final printed page and consequently enables a saving in paper to be made.

The principal object of the present invention is to provide an improved device to perform the preliminary drying and forming of the matrix which will promote greater shrinkage of the matrix.

In the course of my experiments to obtain greater shrinkage in the matrix I found that both the high vacuum, (that is where the degree of rarifaction is great) and high degree of heat employed in the present vacuum formers and driers have a tendency to retard the shrinkage in the matrix or mat. I found also that most of the shrinkage will take place during the earlier stages of the drying.

Another object of this invention therefore is to provide a matrix drier and preliminary former in which a lower vacuum. (that is where the degree of rarifaction is not great) is required for holding the matrix firmly against the forming plate during the initial stages of the drying.

A further object of this invention is to provide an improved heating medium whereby the matrix, at least during the early stages of the drying, will not be required to be subjected to the intense heat now employed in matrix driers and formers.

An additional object is to provide an improved drier and shrinker in which adjustable spring pressure applied against the two straight edges of the matrix during the drying will aid in increasing the matrix shrinkage.

A further object of this invention is to provide a device for drying, forming, and shrinking the matrix in which the actual amount of shrinkage which takes place in the width of the matrix will be constantly indicated.

A still further object is to provide a drier and shrinker with a control governed by a predetermined desired amount of shrinkage of the matrix, whereby the operation of the device will be 2 automatically halted when such predetermined amount of shrinkage has occurred.

The manner in which these objects and incidental advantages are attained with my invention will be explained in connection with the following brief description of my improved matrix drier and shrinker. In the following description reference is to be made to the accompanying drawings, in which:

Fig. 1 is a side elevation of my improved drier and shrinker with portions of the outside casing broken away to show the general arrangement of the interior members and parts;

Fig. 2 is a vertical section taken on line 2-2 of Fig. 1, drawn to a slightly smaller scale and with parts shown broken away for the sake of clarity;

Fig. 3 is a sectional plan view corresponding to line 3-3 of Fig. 1, drawn to a still smaller scale, and illustrating the foot treadle or means for releasing the matrix in the device;

Fig. 4 is a view in perspective of the entire device;

Fig. 5 is a fragmentary view of the shrinkage indicator;

Fig. 6 is a plan view, partly in section, taken on the line 6 6 of Fig. 1, showing the matrix in place in my device;

Fig. 7 is an enlarged fragmentary sectional view taken on line 1-1 of Fig. 6, illustrating the operation and function of the side holding bars; and

Fig. 8 is an enlarged fragmentary section taken on line 8-8 of Fig. 6 showing further details in connection with the side holding bars.

My matrix drier and shrinker is not intended to serve as a complete substitute for the customary vacuum former and drier, but, more correctly, should be described as a pre-drier and shrinker, performing partial drying and increased shrinking of the matrix preliminary to the final drying and forming of the matrix.

The nal stage in the drying and forming is intended to be accomplished by the present customary former and drier in which the matrix may be subjected to higher temperature and higher vacuum to speed up the final stage of the drying and forming.

Referring rst to Figs. 1 and 2, a vacuum chamber I, having a curved, perforated top wall 2 for supporting the matrix, is mounted on suitable supporting brackets within the cabinet or housing 3. A blower, or air-exhausting means, l is mounted` below the vacuum chamber l, and is connected therewith by manifolds or

ducts

5 and 6. A suitable discharging outlet 'I is provided for the air-exhausting means enabling the air and moisture exhausted from the vacuum chamber to escape through an opening I2 in the lower portion of the housing. The air-exhausting means d is provided with the usual exhaust fan (not shown) driven by a motor 8 through suitable belt and pulley connections.

A pair of side holding bars 23 extend in parallel horizontal position on the top of the vacuum chamber, along each side respectively, and parallel to the axis of curvature of the perforated top 2 of the vacuum chamber. One of the purposes of these bars is to engage and hold the opposite straight sides of the matrix. These bars are movably mounted so as to slide laterally towards or away from each other in unison while resting on the top of the vacuum chamber.

Brackets I6, extend downwardly from the vacuum chamber I, being located adjacent the four corners of the vacuum chamber respectively. A horizontal stub shaft I5 is secured in each bracket I6 and a rocker arm I3 is pivotally mounted on each stub shaft I5. The rocker arms I3 are tubular and a plunger I`I, (see Figs. 2 and 8), is slidably mounted in the top portion of each rocker arm I3. A spring I8 on each plunger I'I, having one end bearing against the enlarged bottom end I9 of the plunger and the other end against a retaining sleeve screwed in the top of the arm I 3, tends to pull the plunger downwardly. The top ends of the plungers I I are pivotally connected to wrist pins 22 mounted in the ends of the side holding bars 23. Thus the plungers I'I keep the side holding bars 23 bearing on the top perforated surface of the vacuum chamber.

In Fig. 7 it will be noted that the longitudinal edge of the holding bars 23 adjacent the matrix 2'I is formed with a beveled notch or overhanging ridge 25 ,to extend over the matrix edge and keep the matrix edge pressed down against the perforated top 2 of the vacuum chamber.

To the bottom end of each rocker arm I3 a link 28 is pivotally connected, these links being shown most clearly in Fig. 2. The inner ends of each pair of these links 28 are pivotally mounted at 3I to the upper end of a vertical rod 30. Each of the two vertical rods 30 (see also Fig. 1) slides through a bracket 33 secured to the side wall of the housing or cabinet. A spring 32 is mounted on each rod 30 and is held under adjustable compression between the bracket 33 and adjusting nut 34 carried on the rod 30. The bottom ends of the two rods 38 are joined by a horizontal bar (Fig. 1) and a suitable foot lever or treadle 29 is mounted in the bottom of the cabinet and bears on the bar 35 so that downward pressure on the free end of the treadle 29 will operate to pull the two vertical rods 30 downwardly vagainst the force of their springs 32. The foot treadle is accessible to the operator through the opening I2 at the bottom of the cabinet as shown in Fig. 4.

As apparent from Fig. 2, downward pressure on the foot treadle 29, pulling the rods 30 downwardly, will cause the links 28 to pull the bottom ends of the rocker arms I3 inwardly. This will result in the upper ends of the rocker arms I3 and plungers I1 being moved outwardly with the result that the holding bars 23 will be moved outwardly or away from each other.

When a matrix is to be inserted in the device the foot treadle is pressed down causing the bars 23 to be moved outwardly and held in such position while the matrix is being placed on the perforated top 2 of the vacuum chamber I. Then the treadle is gradually released and the bars 23, due to the action of the springs 32, move towards each other until they engage the respective edges of the matrix. The `holding bars 23 not only insure the proper positioning of the matrix on the perforated surface but also at all times keep the straight edges of the matrix held rmly in contact with the surface on which the matrix is supported. The rest of the matrix is held firmly against this top surface of the vacuum chamber by the\`suction through the perforations in the top into\the vacuum chamber I due to the operation ofthe air exhausting means 4.

However, in my invention these holding bars 23 perform an important further function. The normal action of the springs 32, tending to push the rods 30 upwardly and the holding bars 23 inwardly towards each other, causes these bars 23 to exert lateral pressure along both longitudinal side edges of the matrix and this lateral pressure or compression of the matrix, particularly during the first stages 'of the drying of the matrix, increases the shrinkage of the matrix. This is a novel and important feature of my invention. The amount of lateral pressure exerted on the matrix by the holding bars 23 can be varied by adjusting the tension of the springs 32 through the medium of the adjusting nuts 34. The lateral compression must of course not be too strong or else there might be a tendency for the matrix to buckle, and the amount of lateral compression which may safely be exerted will depend to some extent upon the height of the vacuum maintained in the vacuum chamber, since the greater the vacuum the more firmly will the matrix be held by suction against the perforated top of the vacuum chamber. On the other hand, since the holding bars 23 will hold the longitudinal side edges of the matrix firmly against this top surface at all times, a lower vacuum can be maintained in the vacuum chamber than is ordinarily required in ordinary vacuum formers and driers, and no excessive passage of air under the sides of the matrix into the vacuum chamber, which would decrease the vacuum, will occur. As mentioned previously, I have found that the maintenance of a low vacuum, instead of a high vacuum, also increases the shrinkage of the matrix and thus with my device I preferably maintain a low vacuum and adjust the springs 32 accordingly.

Below one end of the vacuum chamber I I provide a control or shut-oil switch 3'I (Figs. 1 and 2). This switch 3'I is connected with the motor 8, which operates the blower 4, and is also connected with the heating element to be described later, so that the operation of the shut-off switch 31 win result i shutting off the current both to the motor and to the heating element. The switch 31 includes a spring-controlled plunger 40 which extends downwardly. A bracket arm 38 (Fig. l) is adjustably mounted, by means of a suitable screw clamp 39, near the top of the vertical rod 30 below the switch 31 and is so arranged as to contact the plunger 40 of the switch 3`I and push the plunger upwardly, thus operating the shut-off switch 31, when the rod 30 rises a predetermined amount. But the upward movement of the rods SI1-will, as apparent from Fig. 2, depend upon the lateral shrinkage of the matrix which will permit the holding bars 23 to move inwardly, the bottom ends of the rocker arms I3 to swing outwardly, and the inner ends of the links 28 to be pushed upwardly. In other words, the shut-off switch 3'I, by proper adjustment of the bracket arm 38, can be caused to operate automatically whenever a desired predetermined shrinkage has occurred in the matrix. This is another important feature of my invention.

In order to determine the amount of shrinkage which has occurred at any time in the matrix during the operation of my device I provide an indicating or calipering means connected with one of the holding bars 23 or rocker'arms I3.

In Figs. 1 and 5 I show a simple form of such indicating means comprising a pointer 44 secured to one of the rocker arms I3. This pointer has an off-set end which extends through a curved slot 45 in the side of the cabinet or housing 3. A suitable indicating scale 46 is marked above the slot 45 to indicate te exact position of the rocker arm, and, since all the rocker arms operate simultaneously and to the same extent, an indicator attached to one of the rocker arms I3 will suffice for determining correctly the shrinkage of the matrix. Other calipering means, associated with the holding bars 23, rocker arms I3, or rods 3U, could of course be substituted for ,he simplified means which I have shown.

In place of the electrical heating and drying elements customarily employed in matrix farmers and driers I employ a plurality of infra-red lamps 3B (Fig. 2) for this purpose. Since one of the objects of my invention is to avoid the use of the intense heat customarily employed in the drying of the matrix, particularly during the first stages of the drying and shrinking of the matrix, I have found that infra-red lamps are highly satisfactory in providing just the right amount of drying heat during the preliminary drying and shrinking of the matrix for the most eilicient accomplishment of my purpose.

These infra-red lamps are mounted in sockets supported in a curved plate 41 forming the bottom of a closed housing 48 which contains suitable electrical wiring connections and which is removably and adjustably supported in an opening 49 (see also Fig. 4) provided in the top of the cabinet 3. The cabinet 3 is formed with a downwardly extending flange 50 about the opening 49, and rows of adjustitng holes 5I in the flange 50, in vertical alinement with registering holes in the sides of the housing 48 for the insertion of supporting screws, enable the housing 48, and with it the infra-red lamps 36, to be set closer to, or further away from, the matrix, or enable the housing 4-8 and lamps to be entirely removed from the top of the cabinet 3 when any repairs or replacements are required in the heating element. The bottom plate 41, in which the lamps 36 are supported, has a curvature of substantially the same radius as the top of the vacuum chamber I, so that all portions of the matrix will be approximately the same distance from the lamps.

The front wall of the cabinet 3 is provided with a suitable hinged door 24, located above the vacuum chamber' I, extending practically the entire width of the cabinet, to enable the matrix to be easily placed within or removed from the device.

As previously mentioned, my drier and shrinker is not designed to take the place entirely of the matrix formers and drlers now at present in use, but `is intended primarily to be employed only i of the matrix, thus during the period of vgreatest shrinkage. After the predetermined or desired amount of shrinkage has been obtained in my device it is intended that the matrix then be removed. The vacuum suction is shut 01T and the foot treadle 29 is pressed down to enable the matrix to be lifted from the perforated top 2 of the vacuum chamber. Then the matrix is placed in an ordinary vacuum dryer and former, such, for example, as that described in U. S. Letters Patent No. 1,960,697, of Cochran, et al., dated May 29, 1934, in which the matrix can be subjected to a higher degree of heat and higher vacuum. This higher heat and vacuum will speed up the nal drying of the matrix. Inasmuch as the desired shrinkage will have occurred in the matrix before its removal from my device, the fact that very little shrinkage will occur under the high temperature and high vacuum during this last and final drying and forming stage will not then matter.

I claim:

l. In a device of the character described, a vacuum chamber, a perforated wall on said vacuum chamber, air-exhausting means connected with said chamber, a pair of matrix-holding pressure bars positioned on said wall and adapted to engage the longitudinal side edges of the matrix, pressure means causing said bars normally to move towards each other to press the longitudinal side edges of the interposed matrix inwardly and thereby cooperate with and increase the tendency of the matrix to shrink laterally while drying, bar-disengaging means for moving said bars outwardly away from the matrix edges, heating means for supplying heat to the exposed surface of the matrix when said matrix is positioned on said wall, a control connected with said heating means and said air-exhausting means adapted, when actuated, to stop the operation of said heating means and said air-exhausting means, an actuating element for said control, said actuating element connected with said barpressure means and adapted to actuate said control and thereby stop the operation of said heating means and said air-exhausting means when the shrinkage of the matrix has caused said holding bars to move inwardly a predetermined distance.

2. In a stereotype matrix former and drier, a vacuum chamber, a perforated wall on said vacnum chamber, air-exhausting means connected with said chamber, a pair of matrix-holding pressure bars substantially parallel to each other positioned on said wall and adapted to engage the longitudinal side edges of the matrix, adjustable spring pressure means causing said bars normally to move towards each other to press the longitudinal side edges of the interposed matrix inwardly and thereby 'cooperate with and increase the tendency of the matrix to shrink lateraliy while drying, bar-disengaging means for moving said bars outwardly away from the matrix edges, heating means for supplying heat to the exposed surface of the matrix when said matrix is positioned on said wall, a control connected with said heating means adapted, when actuated, to stop the operation of said heating means, an adjustable actuating element for said control, said actuating element connected with said bar-pressure means and adapted to actuate said control and thereby stop the operation of said heating means when the shrinkage of the matrix has caused said holding bars to move inwardly a predetermined distance.

3. In a stereotype matrix former and drier, a

vacuum chamber, a perforated wall on said vacuum chamber, air-exhausting means connected with said chamber, a pair of matrix-holding pressure bars substantially parallel to each other positioned on said wall and adapted to engage the longitudinal side edges of the matrix, adjustable pressure means causing said bars normally to move towards each other to press the longitudinal side edges of the interposed matrix inwardly and thereby cooperate with and increase the tendency of the matrix to shrink laterally while drying, bar-disengaging means for moving said bars outwardly away from the matrix edges, heating means for supplying heat to the exposed surface of the matrix when said matrix is positioned on said wall, a control connected with said heating means and said airexhausting means adapted, when actuated, to stop the operation of said heating means and said air-exhausting means, an actuating element for said control, said actuating element connected with said bar-pressure means and adapted to actuate said control and thereby stop the operation of said heating means and said air-exhausting means when the shrinkage of the matrix has caused said holding bars to move inwardly a predetermined distance.

4. A device of the character described including a vacuum chamber, a perforated wall on said vacuum chamber, airexhausting means connected with said chamber, a pair of matrix-holding pressure bars substantially parallel to each other positioned on said wall and adapted to engage the longitudinal side edges of the matrix, ad-

justable spring pressure means causing said bars normally to move towards each other to press the longitudinal side edges of the interposed ma.-

trix inwardly and thereby cooperate with and increase the tendency of the matrix to shrink laterally while drying, bar-disengaging means for moving said bars outwardly away from the matrix edges, heating means for supplying heat to the exposed surface of the matrix when said matrix is positioned on said wall, and a control connected with said heating means and said air-exhausting means adapted, when actuated, to stop the operation of said heating means and said air-exhausting means, an adjustable actuating element :for said control, said actuating element connected with said bar-pressure means and adapted to actuate said control and thereby stop the operation of said heating means and said air-exhausting means when the shrinkage of the matrix has caused said holding bars to move inwardly a predetermined distance.

CRAIG C. BAKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS