US1725779A - Plate clamp - Google Patents

Description

Aug. 27, 1929. J, R, BLM'NE 1,725,779

PLATE CLAMP Filed June .10, 1927 +5 @j 555x356 if Ja jim/22W:

Patented Aug. 27, 1929.

UNITED STATES PATENT OFFlCE.

JOSEPH R. BLAINE, OF OAK PARK, ILLINOIS, ASSIGNOR TO THE MIEIILE PRINTING PRESS n MANUFACTURING COMIANY, OF CHICAGO, ILLINOIS, A CORPORATION F ILLINOIS.

PLATE CLAMP.

Application led .Tune 10,

This invention relates to means for securing a flexible sheet to a supporting surface. It is more particularly adapted for positioning and holding a flexible printing plate or the like on a printing element of a printing press.

In connection with certain types of printing presses, for example, Where the design or matter to be printed is provided on a metal or other flexible sheet, such sheet must be securely clamped to and stretched over a supporting member, such for example as a flat bed or as a cylinder. rlhis is usually accomplished by means of one or more series of relatively movable clamping devices arranged in spaced relation on the supporting member to engage opposite edges of the flexible sheet or plate and adapted to pull the latter taut over the supporting member.

For the purpose of accurately positioning a flexible printing plate or the like on its supporting surface, it is desirable to mount the plate so that it can be shifted laterally of its supporting member, i. e. longitudinally, or axially if applied to a cylindrical support.

It is, therefore, the principal object of my invention to provide simple, reliable and efficient means whereby a flexible sheet such as a printing plate or the like can be readily shifted on its supporting member Without or edges of the sheet.

A further object of the invention resides` in the provision of simple and practical means for shifting as a unit all of the clamping members secured to one edge of a clamped sheet.

Other objects of the invention will be apparent from the following description and appended claims.

I have chosen to illustrate and describe a' preferred form of my invention as applied to a lithographie or offset printing press. However, inasmuch as the invention is susceptible of embodiment in various forms of construction and adapted for other uses Without departing from the spirit thereof, I 4do not Wish to limit the invention to the particular form illustrated and described, but I intend to cover all possible modifications that may come Within the spirit and scope of the appended claims.

In the accompanying drawings,

1927. Serial No.-197,795.

Figure 1 is a cross-sectional view taken through a printing press cylinder to which my invention is applied, and showing more specifically the general arrangement of the actual clamping means;

Figure 2 is a similar View of a printing press cylinder but illustrating the scheme for shifting the clamping means illustrated in Figure 1;

Figure 3 is a partial view taken along a plane indicated by the line 3-3 of Figure 1;

Figure 4 is a view of a detail;

Figure 5 is an elevation of a det-ail, taken along line 5 5 of Figure 1; and

Figure G is a cross-sectional view of a detail, taken along line 6 6 of Figure 2.

' For the purpose of mounting the clamping and shifting means which form the subject of my invention, the cylinder 10 is formed With a recessed portion or cavity 11 so as to provide a support 12 for said means. The printing plate 13 of the press is securely clamped and held in position on the plate cylinder 10 by means of the clamping means as clearly indicated in Figure 1. Said means comprises a block 14, Which forms the lovver clamping member and Which is adapted to slide over the surface 15 of thesupport 12 by turning the threaded tensioning spindle 16 which is journaled at 17 Wit-hin a horiv Zontal bearing slot 46 provided in the bracket detaching the clamping means from the edge 18, see Figure 5. Said bracket is preferably secured to the support 12 by means of one or more bolts 19. Tle inner end of the spindle 16 is formed With a trunnion Which is journaled at 20 Within a laterally shiftable bar 21. For the purpose of providing a stop for the edge of the printing plate or the like, the block or lower clamping member 14 is preferably provided at each end with projections 22 as shown in Figures 1 and 3.

The upper clamping member 23 which cooperates With the block14 is mounted on a shaft 24, which is loosely supported Within rearwardly extending portions of the block 14 and held in position by Cotter pins 25. The clamping member 23 is provided With an elongated slot 26 which receives the locking bolt 27. The latter is threaded at 28 into the block 14 and is formed with a collar 29 which bears against an abutment surface on the clamping member 23. The block 14 is forced against the collar 29 by means of an expansion coil spring 32 housed Within recesses and 31 which are provided in the block 14 and in the member 23 respectively so as to separate the clamping jaw of said member from the jaw portion of the block 14 when the bolt 27 is loosened, In order to move the block 14, together with its associated parts, over the supporting surface 15, either for the purpose of tensioning or releasing the tension of the flexible sheet 13, a wheel 33, formed with pin holes 34, is preferably mounted on said spindle adjacent the outer end thereof.

Referring to Figure 2, the means for laterally shifting the bar 21, and therewith the clamping members 14 and 23 and associated parts, comprises a shifting spindle formed at its outer end with a journal 36 mounted within the bracket 37 which is secured to the support 12 by means of bolts 38. The inner end of the shifting spindle 35 is supported by means of a trunnion 39 journaled at 40 within the cylinder wall. The shifting spindle is formed with an excentric 41 which engages within a vertically disposed cam slot 42 provided in the shifting bar 21.

It will be evident upon inspection of Figures 2 and 3 that when the spindle 35 is turned, for example in an anti-clockwise direction, by means of a` pin wrench applied to the pin hole 43, the shifting bar 21 will be shifted to the right or vice versa. Preferably, the bar 21 is supported and guided by means of shoulder bolts 44 which pass through horizontal slots 45 in said bar.

Inasmuch as the threaded tensioning` spindle 16 at each unit of clamping members, such as illustrated in Figure 3 and of which there may be any desirable number, is journaled at its inner end Within the bore 2O of the shifting bar 21, while its outer end is supported wit-hin the elongated slot 46 of the bracket 18, it will follow the shifting movement of said bar, therefore the clamping members will slide over the surface 15 in whichever direction the bar 21 is shifted, and align themselves automatically.

It will be understood of course that prior to shifting the bar 21 it is essential to loosen up each tensioning shaft 16 to some extent so as to reduce the friction between the flexible sheet and its supporting` member.

It has been suggested to provide antifriction means between the tensioning screw of a plate clamp and its bearing surface on the plate supporting member, so that the plate may be shifted without previously releasing its tension. It is obvious, however, that such devices are impractical, particularly when applied to convex supports, and that in order'to avoid any distortion of a printing plate or the like it is necessary to relax the tension of such plate.

I claim:

1. The combination with a flexible sheet supporting element, of means for securing the flexible sheet thereto, comprising a series of holding elements adapted to engage said sheet, and means operatively connected with each one of said holding elements for positively shifting said elements, and the flexible sheet laterally without the necessity of releasing the holding elements therefrom.

2. The combination with a flexible sheet supporting element, of means for securing the flexible sheet thereto, comprising a series of holding element-s adapted to engage said sheet, and a shifting bar arranged to engage each one of said holding elements for shifting the latter as a unit relatively to said supporting element, without the necessity of releasing the holding elements from said flexible sheet.

3. The combination with a flexible sheet supporting element, of means for securing the flexible sheet thereto, comprising a series of holding elements adapted to engage said sheet, and a cam actuated shifting bar arranged to engage each one of said holding elements for shifting the latter as a unit relatively to said supporting element, without the necessity of releasing the holding elements from said flexible sheet.

4. The combination with a supporting element for a printing plate or the like, of means for holding the printing plate or the like rigid on said element, comprising a series of independently operable clamping members adapted to engage and grip the edge of said printing. plate or the like, and means arranged to engage each one of said clamping members for shifting them as a unit longitudinally of said supporting element.

5. The combination with a flexible sheet supporting element of a printing press or the like, of means for securing the flexible sheet to said element, comprising series of independently operable shifting clamps adapted to clamp opposite edges of said sheet, and means arranged to engage each one of a series of clamps for shifting the clamps on each edge as a unit relatively to the supporting element, for the purpose of positioning the sheet thereon. 6. In combination with a flexible sheet supporting element, an adjustable member associated therewith, a shifting spindle for operating said member, a series of sheet holding members engaged by and mounted for unit adjustment with said adjustable member, and means for automatically align- Iing said holding members as they are being adjusted.

7. In combination with a flexible sheet supporting element, a cam actuated, adjustable shifting bar associated therewith, a shifting spindle for operating said bar, a series of sheet holding members engaged by and mounted for unit adjustment with said adjustable member, and means for automatically aligning said holding members as they are being adjusted.

8. In combination with a printing plate or the like supporting element, a ylaterally shiitable member associated therewith, a shitting spindle for operating said member, a series of independently adjustable holding members engaged by and mounted for unit adjustment with said shiftable member, and means for aut-omatically aligning said holding members as they are being adjusted.

9. In combination with aprinting plate or the like supporting elements, a manually adjustable bar associated therewith, a shifting spindle for operating said bar, a series ot' independently adjustable clamping members engaged by and mounted for unit adjustment with said adjustable bar, and means for automatically aligning said holding members as they are being adjusted.

l0. In combination with a flexible sheet supporting element, an adjustable member associated therewith, a. series of sheet holding members mounted for unit adjustment with said adjustable member, tensioning means operatively engaging said sheet holding members. and means for aligning said tensioning means and holding members.

l1. In combination with ay iiexible sheet supporting element, a laterally adjustable member associated therewith, a series of independently adjustable sheet holding members mounted for unit adjustment with said laterally adjustable member, tensioning means operatively engaging said sheet holding members, and means for simultaneously aligning said tensioning means and holding members during the lateral adjustment of the latter.

l2. In combination with a supporting element for a printing plate or the like, a cam actuated, laterally shiftable member associated therewith, a series' of independently adjustable clamping members mounted for unit adjustment with said cam actuated member, tensioning means operatively engaging said clamping members, and selfaligning means for said tensioning means and clamping members.

18. A shifting plate clamp for positioningk a printing plate on a cylinder of a printing press, comprising a plurality of cooperating clamping members arrange-d in pairs at intervals along an edge of the printing plate, means for independently securing each pair of clamping members to said plate, tensioning means operative to stretch said plate taut over the cylinder, means comprising a shifting bar mounted on the cylinder wall and supporting said tensioning means, means operative to shift said bar and thereby move the clamping members as a unit longitudinally otthe cylinder, and means for aligning said tensioning means and clamping member during the longitudinal movement of the latter` 14. A shifting plate clamp for positioning a printing plate on a cylinder ot a printing press, comprising a plurality oi cooperating clamping members arranged in pairs at intervals along an edge of the printing plate, means for independently securing each pair et clamping members to said plate, means operative tostretch said plate taut over the the cylinder, a shifting bar mounted on the cylinder wall and supporting said last referred to means, means operative toy shift said bar, together with the means supported thereby, relatively to the cylinder and comprising a shifting spindle formed with an eXcentric portion which engages within a cam slot in said bar.

Signed at Chicago, Illinois, this 6th day of June, 1927.

JOSEPH R. BLAINE.

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