US3167004A

US3167004A - Stencil screen frame

Info

Publication number: US3167004A
Application number: US283792A
Authority: US
Inventors: Henry L Miller; Thomas R Ramsden
Original assignee: WEST PENN SCREEN SERVICE Inc
Current assignee: WEST PENN SCREEN SERVICE Inc
Priority date: 1963-05-28
Filing date: 1963-05-28
Publication date: 1965-01-26
Anticipated expiration: 1982-01-26

Description

Jan- 26, 1965 H. L. MILLER ETAL STENCIL SCREEN FRAME 2 Sheets-Sheet 1 Filed May 28, 1963 S N Y R M m a 2a x m EL T ID wm mR m mm m Y WMM HT m m9.

3 mm mm Jan. 26, 1965 H. L. MILLER ETAL STENCIL SCREEN FRAME 2 Sheets-Sheet 2 Filed May 28, 1963 INVENTORS. HENRY L. MILLER THOMAS ;AMSDEN their ATTORNEY United States Patent() Filed May 28, 1963, Ser. No. 283,792 11 Claims. (ill. 101-4271) This invention relates to a frame for supporting a stencil screen, and more particularly to a unitary frame having contiguous stencil screen retaining means.

One major problem associated with prior art stencil 'screen frames concerns their ability to maintain the stencil screen in a taut condition. Most prior art stencil screen frames are comprised of two separate types of components, namely, theframe itself and one or more extrinsic elements which are used to secure the stencil screen to "the frame. Theseextrinsic elements may comprise, as for example, a cord for tying the stencil screen to the frame or wedge members which are adapted to be inserted into recesses in the frame in such a manner that the stencil screen is simultaneously stretched. It should be noted, hcweventhat these methods of securing the stencil screen to the frame are time consuming and more important, there is no positive assurance that the stencil screen will remain on the frame while the frame is being used in a printing process.

Accordingly, the primary objects of the present invention include:

To provide a unitary stencil screen frame having novel contiguous means for securing the stencil screen to the frame;

To provide a unitary stencil screen frame having novel contiguous screen securing means which assures a positive connection between the stencil screen and the frame;

To provide a unitary stencil screen frame having novel contiguous screen securing means whereby a stencil screen may be quickly and easily secured to the frame;

To provide a unitary stencil screen frame having resilient side members which maintain a stencil screen in a taut condition; and

To provide a stencil screen frame which is lightweight and disposable. p I These and other objects and advantages of the present invention will become apparent from the following detailed description by reference to the accompanying draw- 4-4 of FIG. 1, illustrating one wall member of the present stencil screen frame;

FIG. 5 is a cross-sectional view, taken along the line 5-5 of FIG. 1, illustrating another wall member of the present stencil screen frame;

FIGS. 6 and 7 are fragmentary cross-sectional views similar to FIG. 3 and illustrating the means by which a stencil screen is secured to the present frame;

FIG. 8 is a bottom plan view of an alternative embodiment of the present stencil screen frame;

FIG. 9 is a cross-sectional View taken along the line 9-9 of FIG. 8;

FIG. 10 is a top plan view of a further alternative embodiment of the present stencil screen frame;

FIG. 11 is a cross-sectional view, taken along the line "ice lib-11 of FIG. 10, further illustrating the embodiment of FIG. 10;

FIG. 12 is a top plan view of a second frame used in conjunction with the stencil screen frame of FIG. 10;

FIG. 13 is a cross-sectional view taken along the line 13-43 of FIG. 12;

FIG. 14 is a fragmentary isometric view illustrating a clamping means used in conjunction with a metal stencil screen mounted on the preferred embodiment of the present stencil screen frame; and

FIG. 15 is a cross-sectional view, taken along the line 15-1 of FIG. 14, further illustrating the clamping means of FIG. 14.

According to the preferred embodiment of the present invention, a unitary, lightweight stencil screen frame is provided having a plurality of wall members which define an opening in the frame. The stencil screen frame preferably is formed from lightweight, resilient, plastic materials whereby it is resistant to the deteriorating efiects of present day printing inks. Furthermore, the present stencil screen is relatively inexpensive and therefore is of the disposable type. The wall members have outer edges which lie in substantially the same plane. Fusible means is provided which preferably is contiguous with the outer edges of the wall members. The fusible means serves to secure the stencil screen to the frame. The fusible means preferably comprises a bead of thermoplastic material which may be melted by the application of heat and which, when melted, will fuse with the stencil screen to secure the same to the frame.

In the preferred embodiment, the frame includes a pair of opposed wall members which preferably are normally outwardly bowed. Since the frame is formed from a resilient material, these wall members are adapted to be bent or bowed inwardly when the prestretched stencil screen is secured to the frame. When the inwardly bent wall members are released they tend to move outwardly into their normally outwardly bowed position whereby the stencil screen is stretched and maintained in a taut condition.

According to an alternative embodiment of the present invention, the outwardly bowed wall members are each :provided with an arcuate length of spring steel or the like which serves to reinforce the wall members whereby more force is provided in maintaining the stencil screen in a taut condition.

According to a further alternative embodiment of the present invention, aunitary stencil screen frame is provided having a plurality of resilient wallmembers which define an opening in the frame. In this embodiment, all the wall members are normally straight. The stencil is secured to the frame in loose overlying relation with the opening. A rigid frame also is provided which is insertable into the opening of the stencil screen frame. The rigid frame has a pair of outwardly bowed, opposed wall members which engage and outwardly bow the resilient wall members of the stencil screen frame thereby stretch- .20. The frame 2t comprises a

plurality'of side members

22, 24, 26 and 28. The lside

members

22, 24 comprise one pair of opposed side members each of which is normally outwardly bowed. The

side members

22, 24, 26 and 28 define an opening 3b in the stencil screen frame 20 which is covered by a stencil screen when the frame 20 is used in a printing process. As best seen in FIG. 2, the

side members

22, 24, 26 and 28 have outer edges 32 all of which lie in substantially the same plane.

Referring to FIGS. 1 and 4, the side member 22 preferably has an L-shaped transverse cross section and comprises a vertical wall member 34 and a flange member 36 which projects laterally therefrom. The side member 22 also includes a plurality of rib members 38 which serve to reinforce the side member 22 and maintain its L-shaped configuration.

Referring to FIGS. 1, 2 and 5, the side member 24 preferably has a similar L-shaped transverse cross-section and comprises a vertical wall member 34 and a flange member 4t) which projects laterally therefrom. The side member 24 also includes a plurality of rib members 42 which serve to reinforce the side member 14 and maintain its L-shaped configuration.

Referring to FIGS. 1 and 2, the

side members

26, 28 each include a vertical wall member 34 and a flange member 44a, 4412, respectively. Reinforcing rib members 46 extend between the vertical Walls 34 and the

flange members

44a, 44b and serve to maintain the L-shaped configuration of the

side members

26 and 28. The flange member 44a is provided with an opening 48 while the flange member 44b is provided with a slot 5th. The opening 48 and the slot 50 provide for securing the frame 20,

as for example, to support arms 51 one of which is shown in phantom outline for subsequent securement on a stenciling machine (not shown) in decorating relation with an object to be decorated.

The frame 2% preferably is formed from a lightweight, resilient, plastic material which has the property of being 7 thermoplastic. The frame 20 preferably is formed from the crystalline form of polypropylene. Alternatively, the frame 20 could be formed from other thermoplastic materials such as molded nylon, polyacetyl which is a product sold under the trade name Delrin, or polycarbonate which is a product sold under the trade name Lexan.

As can best been seen in FIG. 1, the

flange members

44a, 44b of the

side members

26 and 28, respectively, arerelatively wide flanges which cooperate with the rib members 46 so that the

side members

26 and 28 are substantially rigid. On the other hand, the

flange members

36 and 40 of the

side members

22 and 24, respectively, are narrow whereby the

side members

22 and 24 are resilient and may be bent. Since the

side members

22 and 24 are resilient, they may be displaced inwardly, that is, toward each other. The side member 24 has been illustrated. in phantom outline in an inwardly displaced position which is designated by the numeral 24'. The resiliency of the

side members

22, 24 is an important feature of the present frame 20 which will be more fully described later in the specification.

As hereinbefore stated, the present invention provides a novel screen retaining means which is contiguous with the stencil screen frame 20. Referring now to FIG. 3, the upper portion of one of the wall members 34 is illustrated. The outer edge 32 thereof preferably includes a bead 52 which is contiguous therewith and which preferably is centrally disposed thereon. ,The bead 52 preferably extends along the entire length of each of the wall members 34, that is, it extends continuously around the periphery of the opening 3d. As will be remembered,

the frame 20 preferably is formed from a thermoplastic material. Hence, the bead 52 serves as a fusible means for securing a stencil screen to the frame 20. Alternatively, the frame 20 could be formed without the bead 52. In this instance, the outer edge 32 which would serve as a fusible means for securing a stencil screen tothe frame 20;

A description of the ease by which the stencil screen 7 4 may be secured to the frame 20 will now follow with reference to FIGS. 1, 6 and 7.

In FIG. 6, the wall member 34 of the side member 24 is shown in the inwardly displaced posit-ion illustrated in phantom outline in FIG. 1. The direction of the displacement is indicated by the arrow numbered 54. The side member 24 is maintained in this inwardly displaced position by any suitable means such as a jig (not shown) until the stencil screen is secured to the frame 20. A prestretched stencil screen 56 is placed over the outer edge 32, as shown, in overlying relation with the opening 30 in the frame 20. The bead 52 may be melted by the application of heat through the stencil screen 56. The

required heat may be supplied by any suitable heating implement. When the melted bead 52 cools, it will fuse, as indicated at 52' in FIG. 7, with the stencil screen 56 to secure it to the frame 20.

After the stencil screen 56 has been positively secured to the frame 20, the side member 24 is released whereupon it will tend to move outwardly to assume its normally outwardly bowed position illustrated in full lines in FIG. 1. The direction of displacement is indicated in FIG. 7 by the arrow numbered 58.

It should be noted that preferably both of the side mem- 1

bers

22 and 24 are displaced inwardly, as for example,

by use of a jig before securing the stencil screen 56 to the frame 20. When they are released they will tend to move outwardly whereby the stencil screen 56 is stretched and maintained in a taut condition. Alternatively, only one of the side members need be displaced inwardly before securing the stencil screen 56 to the frame 20. As illustrated in FIG. 1, the side member 24 is relatively more flexible than the side member 22 by virtue of its narrower flange member 40. As specifically illustrated in FIG. 1, the side member 24 will undergo considerable inward displacement before the side member 22 may be displaced inwardly. It should be evident then that although only one of the side members is displaced inwardly, the final resulting stencil screen assembly. will have a stencil screen which is maintained in a taut condition at all times.

Reference is now directed to FIGS. 8 and 9 wherein an alternative embodiment of the present stencil screen frame is illustrated and identified by the numeral 60. Corresponding numerals will be employed to identify corresponding parts already described.

In this embodiment, the

side members

22, 24 include a slot 62 (see FIG. 9) extending along substantially their entire length and into the vertical walls 24 thereof. Within'each of the slots 62, there is provided a spring means which preferably comprises an arcuate strip 64 of spring steel which serves to bow the

wall members

22, 24 inthe outward direction illustrated. The arcuate strips 64 serve the further purpose of increasing the outwardly directed force used in stretching a stencil screen as hereinabove described. As can be seen in FIG. 8, each of the arcuate strips 64 are shorter than slot 62 whereby a space 65 is provided at each 'end into which the arcuate strips 64 move when the

side members

22, 24 are bowed inwardly. In this embodiment, then, there is provided a positive means for bowing the

wall members

22, 24 in an outward direction.

Reference is now directed to FIGS. 10 to 13 wherein a further alternative embodiment of the present stencil screen frame is illustrated. Corresponding numerals will be employed to identify corresponding parts already described.

In FIGS. 10 and 11 there is illustrated a stencil screen frame 66 having wall members 22', 24' which are normally straight as shown. With the exception of the

straight wall members

22, 24, the stencil screen frame 66 is identical to the stencil screen frame 26 of the preferred embodiment. V

The stencil screen frame 66 is adapted for use in conjunction with a rigid frame 68 which is illustrated in FIGS. 12 and 13. The rigid frame 68 preferably is formed from metal and includes

side walls

70, 72, 74 and 76.

As can be seen in FIG. 13, the side wall '70 has a rigid L-shaped cross-section. It should be noted that the remaining

side walls

72, 74 and 76 also have the same L- shaped cross-section. The side walls74 and 76 have a flange member 7 8 extending therefrom each of which has a pair of

apertures

80, 82. The apertures 80 are so positioned whereby they are concident with the aperture 48 and the slot 50 in the

flange member

44a and 44b respectively of the stencil screen frame 66 (see FIG. and cooperate therewith in receiving fasteners (not shown) for securing the stencil screen frame 66 to the rigid frame 68. The apertures 82 in the flange members 78 are adapted to receive fasteners (not shown) for securing the rigid frame 63 to support arms 84 (one shown in phantom outline) :of a mounting bracket.

When using the stencil screen frame 66, the stencil screen 56 is secured to the outer edges 32 by employing the bead 52 as described in connection with the preferred embodiment. However, in this instance, the stencil screen 56 is secured in a loose overlying relation with the opening 30 as illustrated in FIG. 11, i.e., the stencil screen 56 is allowed to sag slightly. The stencil screen frame 66 is then .fitted over the rigid frame 68 whereupon the arcua-

te side walls

70, 72 of the rigid frame 68 force the resilient wall members 22, 24' of the stencil screen frame 66 to assume a similar arcuate shape. By bowing the resilient wall members 22, 24' in an outward direction, the stencil screen 56 (see FIG. 11) is stretched into a taut condition and is ready to be used.

The cooperating stencil screen frame 66 and rigid frame 68 are particularly adaptable for use with stencil screens which are easily punctured when in a stretched condition. That is to say, some stencil screen materials are relatively thin and must be handled with some care. Hence, by securing this type of stencil screen to the stencil screen frame 66 in a loose manner as illustrated in FIG. 11, the stencil screen frame may be handled without fear of damaging the stencil screen since, by virtue of its sagging condition, a give in the material is provided. When the screen is to be used, the stencil screen frame 66 is mounted on the rigid frame 68 whereby the stencil screen is stretched in a taut condition ready for use.

It should be understood, however, that this embodiment may be employed, with equal utility, to support any other type of stencil screen.

Referring now to FIGS. 14 and 15, the present stencil screen frames 26, 60 or 66 may be used to support a metal stencil screen to which is applied an electric current for heating the screen. In order to support this type of screen, some means must be provided for connecting the metal screen to a source of electric current. As can be seen in FIG. 14, a stencil screen frame is illustrated which is identified by the numeral 86. The stencil screen frame 86 may comprise any one of the stencil screen frames 20, 60 or 66 each of which is used as hereinbefore described. A metal stencil screen 88 is secured to the stencil screen frame 86 in the manner heretofore described and is maintained in a taut condition ready for use. The metal stencil screen 88 has an end portion 90 which extends from each end thereof.

A pair of

plates

92, 94, comprising cooperating means, are shown clamping the end portion 90 of the metal stencil screen 88 therebetween. The

plates

92, 94 prefer- 6 FIG. 15, the plate 94 includes projecting lugs 104 which serve to maintain the

plates

92, 94 spaced from the structure 100 whereby air is allowed to circulate around the

plates

92, 94 for cooling the same.

At the extreme end of the fastener 96 there is provided a washer 106 upon which rests a contact 108 of an electrical conductor 119. A wingnut 112 is threaded onto the fastener 96 and serves to clamp the

plates

92, 94 in a rigid position and to secure the contact 108 to the fastener 96. Thus the fastener 96 serves to conduct the electric current brought in by the conductor 110.

It should be noted at this point, that the metal stencil screen 88 has two end portions both of which are clamped between similar pairs of the

plates

92, 94 as illustrated in FIGS. 14 and'15. Thus, an electric current is passed through one set of the

plates

92, 94, the metal screen 88 and another set of the

plates

92, 94 at the other end of the metal stencil screen 88.

As illustrated in FIG. 14, the

plates

92, 94 extend for substantially the entire length of the distance between the rib members 46. If desired, the

plates

92, 94 may be made to extend for a distance equal to the width of the metal stencil screen 88 by providing a notch in the rib members 46 at an appropriate height. This may be desirable in case the electrical current is not evenly distributed over the entire width of the screen 88 since an uneven distribution of the electric current may cause hot spots which would melt the screen and/ or the stencil screen frame 86.

Although the invention has been shown in connection with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

We claim as our invention:

1. A generally rectangular stencil screen frame comprising a plurality of generally flattened, resilient wall members defining an opening in said frame, one opposed pair of said wall members being substantially rigid, the remaining opposed pair of side wall members being normally outwardly bowed, means integral with said frame for securing a stencil screen to said wall members in overlying relation with said opening, said wall members being substantially perpendicular to the plane of said stencil screen and cooperating therewith to define a well for receiving a printing medium, said remaining opposed pair of said wall members being adapted to be flexed inwardly while said stencil screen is secured to said frame, said remaining opposed pair of said wall members when released serving to maintain said stencil screen in a tent condition.

2. A generally rectangular stencil screen frame comprising a plurality of generally flattened wall members, one opposed pair of the wall members being substantially rigid, at least one wall member of the remaining pair of opposed wall members being a normally outwardly bowed wall member formed from resilient material, said Wall members defining an opening in said frame, means for securing a stencil screen to said wall members in overlying relation with said opening, said wall members being substantially perpendicular to the plane of said stencil screen and cooperating therewith to form a well for receiving a printing medium, said normally outwardly bowed wall member being adapted to be inwardly flexed when said stencil screen is secured to said frame, said normally outwardly bowed wall member when released serving to maintain said stencil screen in a taut condition.

3. In a stencil screen assembly, the combination comprising a stencil screen frame comprising a plurality of resilient, generally flattened wall members defining an opening in said frame, said wall members being normally straight, a stencil screen secured to said wall members in loose overlying relation with said opening, and means insertable Within said opening for bowing at least one of said wall members outwardly whereby said stencil screen is stretched into a taut condition, said wall members being substantially perpendicular to the plane of said stencil screen when in its taut condition and cooperating therewith to define a well for receiving a printing medium, said means insertable within said opening allowing said opening to be free of interfering matter.

4. A generally rectangular stencil screen frame comprising pairs of opposed side members, one opposed pair of the side members being substantially rigid, at least one of the side members of the'remaining pair of opposed side members being resilient and normally outwardly bowed, fusible means integral with at least one pair of opposed side members for securing a stencil screen to said frame, the normally outwardly bowed side member being adapted to be inwardly flexed into substantially parallel relation With the opposed side member when said screen is fused to said frame, said outwardly bowed member when released serving :to maintain said screen in a taut condition.

5. A stencil screen frame of one-piece molded construction, said frame being molded from a resilient, thermoplastic material and comprising pairs of generally flattened, opposed wall members defining an opening in said frame, a flange member integral with at least the wall members of one of said pairs of opposed wall members, said flange members projecting outwardly from said opening, and a plurality of rib members disposed exteriorly of said opening and integral with said flange members and said wall members, one of said flange members being narrower in width than the other of said flange members whereby the wall member associated with said one of said flange members is relatively more flexible than the wall member associated with the other of said flange members.

6. A generally rectangular stencil screen frame comprising aplurality of generally flattened wall members defining an opening in said frame, one opposed pair of said Well members being substantially rigid, at least one wall member of the remaining opposed pair of wall members being resilient, said one Wall member having a slot formed therein which extends throughout substantially its entire length, resilient means carried within said slot for maintaining-said one wall member in an outwardly bowed condition, and means for securing a stencil screen to said frame in overlying relation with said opening, said one wall member being adapted to be inwardly bowed while said stencil screen is secured to said frame, said one wall member when released serving to maintain said screen in a taut condition.

7. The stencil screen frame of claim 6 wherein said resilient means comprises an arcuate length of spring steel.

8. A stencil screen assembly comprising in combination: a generally rectangular frame having pairs of opposed side members defining an opening in said frame, said frame being molded from resilient, thermoplastic material, a

stencil screen secured to said frame in overlying relation with said opening by liquefying and solidifying portions of said frame, one pair of said opposed side members being substantially rigid, the second pair of opposed side members being normally outwardly bowed side members which are adapted to be flexed inwardly while said stencil screen is secured to said frame, said normally outwardly bowed side members when released serving to maintain said stencil screen in a taut condition.

9. A stencil screen assembly comprising in combination: a generally rectangular frame having pairs of opposed side members defining an opening in said frame, said frame being molded from a resilient, thermoplastic material, each of said side members having one surface disposed in a common plane, a bead projecting above said one surface of each of said side members and extending along major portions of at least one of said pairs of opposed side members, a stencil screen secured tosaid frame in overlying relation with said opening by fusion of said bead to said stencil screen, one of said pairs of opposed side members being substantially rigid, at least one of the side members of the second of said opposed side members being an outwardly bowed side member which is adapted to be flexed inwardly while said stencil screen is secured to said frame, said outwardly bowed side member when released serving to maintain said stencil screen in a taut condition.

10. The stencil screen assembly of claim 9 wherein said head extends completely around the periphery of said opening.

11. In a stencil screen frame assembly, the combination comprising a stencil screen frame including a plurality of normally straight resilient wall members defining an opening in said frame, means for securing a stencil screen to said frame in loose overlying relation with said opening, and rigid frame means insertable within the opening of said stencil screen frame including outwardly bowed opposed side members engaged .with a pair of said resilient Wall members whereby said pair of resilient wall members are bowed outwardly to stretch said stencil screen frame into a taut condition.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 634,954

'1 62 Canada. 718,839 3/42 Germany. 620,629 3 49 Great Britain.

WILLIAM B. PENN, Primary Examiner.

DAVID KLEIN, Examiner.

Claims

1. A GENERALLY RECTANGULAR STENCIL SCREEN FRAME COMPRISING A PLURALITY OF GENERALLY FLATTENED, RESILIENT WALL MEMBERS DEFINING AN OPENING IN SAID FRAME, ONE OPPOSED PAIR OF SAID WALL MEMBERS BEING SUBSTANTIALLY RIGID, THE REMAINING OPPOSED PAIR OF SAID SIDE WALL MEMBERS BEING NORMALLY OUTWARDLY BOWED MEANS INTEGRAL WITH SAID FRAME FOR SECURING A STENCIL SCREEN TO SAID WALL MEMBERS IN OVERLYING RELATION WITH SAID OPENING, SAID WALL MEMBERS BEING SUBSTANTIALLY PERPENDICULAR TO THE PLANE OF SAID STENCIL SCREEN AND COOPERATING THEREWITH TO DEFINE A WELL FOR RECEIVING A PRINTING MEDIUM, SAID REMAINING OPPOSED PAIR OF SAID WALL MEMBERS BEING ADAPTED TO BE FLEXED INWARDLY WHILE SAID STENCIL SCREEN IS SECURED TO SAID FRAME, SAID REMAINING OPPOSED PAIR OF SAID WALL MEMBERS WHEN RELEASED SERVING TO MAINTAIN SAID STENCIL SCREEN IN A TAUT CONDITION.