US3807302A

US3807302A - Roller squeegee device with fluid pressure increasing means

Info

Publication number: US3807302A
Application number: US00164332A
Authority: US
Inventors: H Kudlich
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-07-20
Filing date: 1971-07-20
Publication date: 1974-04-30
Anticipated expiration: 1991-04-30

Abstract

A squeegee device with a roller squeegee for applying a fluid on a material particularly for screen printing includes a guide wall or guide wall member positioned adjacent the periphery of the roller squeegee and extends to the region where the fluid is applied to the material to be worked. The guide wall has a concave face facing the roller squeegee with a gap formed therebetween. The gap is filled with the liquid or viscous compound so that the hydrodynamic pressure of the liquid in the gap is increased. The guide wall may have a cross section of a rounded upper edge and two concave outer surfaces tapering to a pointed lower edge, with one of the concave faces following the curve of the squeegee, the pointed lower edge pointing downwardly and projecting into the region under the roller squeegee. The guide wall may also be formed as part of the limitation wall of a squeegee box, into which the squeegee roller is pivotally mounted.

Description

Unite Kudlich States atent PRESSURE INCREASING MEANS 462,160 2/ 1969 Switzerland 101/ 120 [75] Inventor: Hans Kudlich, Obemdorf-Ebbs, 1,569,439 5/1969 France 101/ 120 Austria [73] Assignee: Peter Zimmer, Kufstein, Austria Primary Pulfrey Assistant Exarruner-R. E. Suter [22] F1led: July 20, 9 Attorney, Agent, or Firm-Wenderoth, Lind & Ponack 21 Appl. No.: 164,332

. [57] ABSTRACT U-S. A squeegee device a roller queegee for [51] Int. Cl B411 15/42 a fl id on a i l i larly for screen printing [58] Field of Search 101/1 19, 120, 124, includes a guide wall or guide Wall member positioned 101/114, 116, 123, 121, 122; 415/90; adjacent the periphery of the roller squeegee and ex- 417/300; 418/154 tends to the region where the fluid is applied to the material to be worked. The guide wall has a concave [56] References C'ted face facing the roller squeegee with a gap formed UNITED STATES PATENTS therebetween. The gap is filled with the liquid or vis- 2,664,050 12/1953 Abresch 418/154 @0113 Compound 80 that the hydrodynamic Pressure of 2,753,794 7/1956 Groak 101 120 x h q i in h gap i increased. The guide wall may 2,782,843 2/1957 Rodenacker... 415/90 X have a cross section of a rounded upper edge and two 3,303,791 2/1967 Doble 418/154 on ave outer surfaces tapering to a pointed lower 3,669,561 6 1972 Mott 417/300x edge, with one f the concave faces f ll i the 3,198,109 8/1965 Dwyer et a1. 101/119 x curve of the squeegee the pointed lower edge pomp 2,419,695 4/1947 Shuttleworth et a1 101/116 UX g downwardly and p j g into the region under 2,180,135 11/1939 Bartho1omew..... 101/119 th Th n l b 3,487,775 1 1970 Chaney et a1 101/114 6 er Squeegee e wa may a so 6 3,098,437 7/1963 Tyma, Jr. et a1... 101/350 formed as Part of the hmltatlon wall of a Squeegee 2,206,570 7/1940 Johnston 101/116 X box, into which the Squeegee roller is Pivotally 2,792,780 5/1957 Jacob 101/119 mounted- 3,352,234 -11/1967 Londahl et a1 101/114 3,596,595 8/1971 Zimmer et a1. 101/120 10 Claims 13 Drawing Figures (I) 9 ii 20 5] Apr. 30, 19 74 FOREIGN PATENTS OR APPLICATIONS vA'immara-somu $8071.30? sum 1 HF INVENTOR HANS KUDLICH ATTORNEYS PRTENIEB APR 30 5974 SHEET 2 0F 7 INVENTOR HANS KUDLICH BY flinM v M ATTORNEYS PAYENIEBAPR 30 m4 SHEET 3 0F 7 INVENTOR HANS KUDLI CH B2 /7 flaw/M ATTOVRNEYS sgsomoz PATTEBAPR 30 m4 SHEEI [IF 7 INVENTOR HANS KUDLICH BY #14 r ATTOR NEYS PATENTEBAPR 30 1974 SHEET 5 OF 7 INVENTOR HANS KUDLICH WYW ATTORN EYS SHEEI 8 0? Y INVENTOR HANS KUDLICIiI ATTORNEY5 y/wiz ROLLER SQUEEGEE DEVICE WITH FLUID PRESSURE INCREASING MEANS BACKGROUND OF THE INVENTION This invention relates to a squeegee device having a rotating roller squeegee for applying a liquid, in particular a highly viscious compound, onto the surface of a material to be worked, particularly for screen printing.

With known squeegee devices it is not possible to apply large quantities of liquid onto the material to be printed. This can result, e.g., in screen printing, in unsatisfactory premeation or the liquid into the textile.

SUMMARY OF THE INVENTION It is an object of the invention to increase the quantity of liquid applied to the material without premature penetration. This object is achieved by providing a guide wall or guide wall member adjacent the periphery of the roller squeegee to provide a gap therebetween. A concave face of the guide wall faces the roller squeegee, and the guide wall extends into the region where the liquid is applied to the material. Thus, the liquid is prevented from contacting the material in an uncontrolled manner. The pressure of the liquid in the gap is increased to ensure better penetration of the goods by the liquid. Also, the gap stabilizes the flow of the liquid. This is advantageous, particularly in the case of printing machines with a printing velocity of more than 100 m/min.

The bottom edge of the guide wall projects into the region under the roller squeegee filled with the liquid.

In accordance with the present invention the wedgeshaped space serving for the hydrodynamic increase in pressure between roller squeegee and material to be worked or the rotary screen is enlarged by the gap formed between the guide wall and the roller squeegee so that a higher pressure can develop in the liquid. This results in a larger quantity of the liquid being applied to the material to be worked by means of the squeegee device according to the invention. Also, due to the enlarged gap any detrimental turbulences are prevented in squeegee devices in fast operating machines (e.g., fast operating rotary screen printing machines).

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention are hereinafter described in detail with reference to the accompanying drawings, without, however, being limited thereto.

FIG. 1 is a vertical section of and FIG. 2 is a section according to line II-ll of FIG. 1 ofa printing device in a rotary screen printing machine;

FIG. 3 is a vertical section in an enlarged scale of the squeegee device shown in FIGS. 1 and 2;

FIG. 4 is a top view of and FIG. 5 is a section according to line V-V of FIG. 4 of a modified embodiment of the lateral end region of the squeegee device;

FIG. 6 is a top view of and FIG. 7 is a section according to line VII-VII of FIG. 6 of a modified embodiment of the lateral end region of the squeegee device;

FIGS. 8l3 are vertical sections of further embodiments of the squeegee device according to the invention.

DETAILED DESCRIPTION OF THE INVENTION The embodiment according to FIGS. 1 to 3 is a squeegee device for a rotary screen printing machine. In a rotary screen 1 whose end pieces 2 are rotatably mounted in screen bearings 3 which are connected to the machine frame 4, there is mounted a roller squeegee 5. The roller squeegee 5 consists of magnetizable material and is attracted by a magnet body attached to the pressure support 6. The magnet body may consist of a series of vertically arranged magnet cores 7, enclosed byspools 8. The material to be printed 9 is moved between the rotary screen I and the pressure support 6 by means of a printing blanket 10. While the material to be printed 9 and the printing blanket 10 move in the direction of arrow 11, the rotary screen 1 rotates in the direction of arrow 12 and the roller squeegee 5 rolls along the inside wall of the screen in the direction of arrow 13. The dye is fed in a manner known per se by a dye tube 14 provided with outlet appertures to a dye supply 15 lying between squeegee 5 and screen 1 upstream of the direction of rotation thereof. Upon rolling along the inside wall of the screen the roller squeegee 5 presses the dye from the dye supply I5 through the holes of the screen onto the sheet of material to be printed 9.

According to the invention a guide wall 16 is provided in the dye supply 15, this guide wall extending substantially over the whole width of roller 5. In crosssection the guide wall has a rounded upper edge and two concave outer surfaces tapering to a pointed lower edge. One concave surface of the guide wall extends a small distance from and generally coaxially to the cylindrical surface of the roller. Thus a relatively narrow gap 18 is formed between the guide wall and the roller. The guide wall is connected to the dye tube 14 by arms 17 such that on rotation of dye tube 14 the width of the gap varies.

As can best be seen from FIG. 3 the trailing or lower edge of the guide wall extends well into the printing area, i.e., the region 19 where dye is to penetrate through the screen 1 into the material 9.

If in such device, screen and material move in the directions of the

arrows

13, 12 and 11, respectively, dye is conveyed by adhesion to the surface of roller 5 through the gap 18 between the roller 5 and the guide wall 16 toward the printing region where it is squeezed through the screen into the material. This requires considerable pressure which may build up gradually from the upper or entrance end of the gap 18, since from this entrance the dye is positively guided and prevented from flowing either into the lower part of the dye supply or through the screen before reaching the printing region 19. Some but considerably less pressure rise is obtained in the gap 20 between guide wall 16 and screen 1.

On the contrary, in known devices, any liquid pressure build up occurs only approximately over region 19, the length of which is only about one fourth of the length of gap 18. Accordingly, the maximum pressure obtainable with guide wall 16 may be about four times higher than without the guide wall, and because of the increase of pressure, the amount of liquid applied to the material increases.

The amount of pressure rise in gap 18 can be controlled by turning the dye tube 14 changing thereby the width and shape of gaps l8 and 20. Noses 21 which are provided on the guide wall assure a minimum distance between the guide wall and the roller.

In the embodiment shown in FIG. 2 the gap 18 between roller squeegee and guide wall 16 is open at both longitudinal ends, so that liquid may pass therethrough, resulting in a certain pressure decrease. This can be effectively prevented by seals attached to the ends of the roller squeegee, as shown in FIGS. 4 and 5 and FIGS. 6 and 7. According to FIGS. 4 and 5 a resilient cylindrical ring 23 preferably madeof a porous material, is mounted on ashaft 22 of the roller squeegee 5. The outer diameter of ring 23 is greater than the outer diameter of roller 5, such that in its uncompressed condition, ring 23 closes the end of gap 18 by bearing against the transverse end plane 24 of guide wall 16, thereby preventing escape of liquid. In the contact area between ring 23 and rotary screen 1 the ring 23 is compressed as can be seen from FIG. 5. The ring 23 thus also seals rotary screen 1. The modification according to FIGS. 6 and 7 shows a ring having frustro-conical sealing lips 25 having the same function as ring 23. Sealing lips 25 are arranged on the shaft 22 of the roller squeegee 5. The inner lip 25 bears against end planes 24 of guide wall 16, thus forming a sliding seal. In order to prevent any damage to lips 25 likely to be caused by the sharp edge 26 between roller squeegee 5 and shaft 22, a ring 27 is arranged in front of sealing lips 25. Ring 27 consists of an elastomeric material of relatively high Shore hardness.

FIGS. 8 to are further embodiments of squeegee devices according to the invention, also for use in rotary screen printing machines.

According to FIG. 8 the roller squeegee 5 is arranged in a squeegee box having four generally vertical walls, two of which are shown as 28 and 31 and which extend parallel to the axis of roller 5, and the other two walls (not shown) are perpendicular to

walls

28 and 31. A guide wall 64 is attached to wall 28, and its concave surface forms a gap 18 with roller 5 through which dye from the dye supply is fed by the dye tube 14 to the region 19, thus effecting a gradual pressure increase in the dye during its passage through gap 18. The guide wall 64 is sealed off towards the rotary screen 1 by a flexible sealing member 29, secured to the guide wall 16 by means of a wedge fastener 30. Thus there remains only one gap 18, contrary to the arrangement of FIGS. 1 to 3. The bottom part of wall 31 ofthe squeegee box has a low friction seal 32 providing a support for the roller squeegee 5 and thus sealing it. The squeegee box is fastened by clamps 33 to the dye tube 14. If the squeegee box is moved upwardly with respect to roller squeegee 5 in the direction of arrow 34, the gap 18 narrows and the increase of pressure changes in the gap. If the lower end of guide wall 64 approaches the periphery of the roller very closely, flow of liquid is throttled, and pressure and quantity of flow will decrease. On the other hand, excessive lowering of the box will result in a wide gap in which'the trailing action of the roller surface will not extend over the whole width thereof, such that near the guide wall 64 stagnation of flow or even back flow may occur, thereby also decreasing the rate of flow. Thus, a'maximum flow is obtained with a gap of certain width which depends on the form of the gap, the rotational speed, viscosity of liquid.

In the embodiment according to FIG. 9 the roller squeegee 5 is arranged in a squeegee box. Guide wall 65 differs from the embodiment of FIG. 8 in that it replaces wall 28 and that it extends over almost half the circumference of the roller squeegee 5. The pressure increasing gap 18 is therefore longer than in the aforementioned embodiments and thus results in a higher pressure and greater flow of liquid.

The embodiment according to FIG. 10 is similar to that of FIG. 9, except that a cylinder 35 is mounted inside the squeegee box above roller squeegee 5 and offset horizontally with respect thereto. Cylinder 35 is provided on the surface thereof with a coating 36 having a series of resilient strips 38 extending parallel to the axis of cylinder 35 and inclined with respect to the radii of the cylinder passing through the bases of the strips. In the squeegee box the dye supply 15 has the level 37. A chamber 39 formed between adjacent strips 38 is filled with dye under level 37. If the roller squeegee 5 moves in the direction of arrow 13 and the cylinder 35 moves in the direction of arrow 40, the dye is transported to the entrance 41 of gap 18. When strips 38 reach this point, they are bent flat by nose 42, and the liquid within chamber 39 is forced downwardly into gap 18, thereby increasing the pressure. Within gap 18 between roller 5 and guide wall 6, a further increase of pressure is effected because of the rotation of roller squeegee 5 and the ensuring carriage of the dye in the gap 18. In this embodiment a very high pressure is produced.

Very high pressure can alsobe obtained by the arrangement according to FIGS. 11 and 12. In a squeegee box 43 a second roller 44 is arranged above the normal roller squeegee 5. the twp rollers rotate in opposite directions indicated by

arrows

60 and 13. The surfaces of the inner walls of the box follow closely the outer surfaces of the

rollers

5 and 44 on one side thereof. On the other sides are formed

gaps

46 and 18 through which die is conveyed downwardly from supply 15 fed from a dye tube (not shown). While flowing through gap 46 the dye builds up a pressure as described above. Thus, when reaching the gap transition area 47 the dye has already a considerable pressure which is further increased when passing through gap 18. Noses 21 extending through the gaps in the direction of flow assure proper spacing of the rollers. Area 47 provides compensation of the forces acting on roller 5. By the pressure increase in gap 18 at the lower portion of roller 5, higher specific pressures act on the bottom portion of the roller than on the upper portion thereof. These forces consequently tend to push roller 5 upwardly. This is;compensated, at least partially, by the provision of area 47 which acts to some degree as a retaining surface. q I

The sealing of the dye under pressure in area 59 is effected in the circumferential direction of roller squeegee 5 on the one hand by the roller squeegee 5 contacting the rotary screen and on the other hand by a sealing lip 53, e.g., of polytetrafluorethylen. Sealing lip 53 extends parallel to the axis of the roller squeegee 5 and is attached to squeegee box 43 and insures that the dye is forced through screen 1 over the distance 19. There can also be provided a plurality of sealing lips.

By changing the speed of rotation of cylinder 44, which does not touch the rotary screen 1, the pressure increase in the dye can be influenced and accordingly adapted as conditions may necessitate. For an intensive feeding of dye or for a strong penetration of the material to be printed (e.g., piled goods) the speed of rotation of the cylinder 44 must be higher than that of the roller squeegee 5. It would be useful in this connection as a variant to the embodiment shown. to make gap 46 narrower than gap 18. The roller squeegee 5, touching the rotary screen 1 is either simply moved by the rotary screen or is driven in such way that the circumferential speed of the roller squeegee 5 is constantly equal to the circumferential speed of the rotary screeen 1, so that there will practically be no wear between roller squeegee 5 and rotary screen 1. The wear of rotary screen 1 by sealing lip 53 is insignificant, the more so if lip 53 is made of a material having a low coefficient of friction with regard to the screen material (preferably nickel). This is particularly the case with polytetrafluorethylen.

An example for the drive of roller squeegee 5 and cylinder 44 can be seen in FIG. 12. Roller squeegee 5 has a shaft 22 projecting therefrom bearing a gear wheel 48. Gear wheel 48 meshes with a gear wheel 49 which also drives a gear wheel 50 secured to the end of the rotary screen 1. The gear ratios of

gear wheels

48 and 50 are designed, in an understood manner, to bear a relationship with the diameters of roller squeegee 5 and rotary screen 1 such that the roller squeegee 5 and rotary screen 1 have the same circumferential speed when gear wheel 49 is driven by drive means 45. Roller 44 is driven by a rotation device 52 via a shaft 51 permanently secured to the end of cylinder 44. The driving device 52 can be a continuous transmission gear receiving its driving motion from the repeat drive 45. Driving device 52 may also be an engine whose speed of rotation is variable to a desired gear ratio to the main drive 45.

The purpose of the electromagnets 8 in printing table 6 is to press the roller squeegee 5 toward the wall of the screen and to prevent upward displacement of the squeegee box 43 and thus also a lifting of sealing lip 53 from the inside wall of the screen. For this purpose the roller squeegee 5 consists at least partially of magnetizable (ferromagnetic) material.

In the embodiment according to FIG. 13 the roller 5' is not in direct contact with the rotary screen 1. Rather, a lower dye chamber 61 is provided between roller 5' and screen 1. It is the object of this arrangement to prevent any wear of the rotary screen 1, which may have a thickness of only some tenths of a millimeter according to modern galvanoplastic methods of production, even if the roller 5 is driven at a higher circumferential speed than the rotary screen 1 for the purpose of a more intensive dye application. The printing blanket with the sheet material 9 thereonmoves in the direction of arrow 11. The rotory screen 1 rotates in the direction of arrow 12. In the interior of the rotary screen 1 there is a squeegee box 43, whose dye supply 15 is fed with dye from the dye tube 14.

According to FlG. 13 there is only one roller 5' in the squeegee box 43 of the squeegee device, such roller rotating in the direction of arrow 13. Roller 5 can be driven by a rotating device arranged outside the rotary screen 1, so that the speed of rotation is adjustable. Depending on the speed of rotation of roller 5', a predetermined pressure increase of the dye flowing through gap 18' is created. The pressure of the liquid in the area 61 beneath the roller 5 is determinative of the amount of dye forced through the holes of the rotary screen 1 in the area of zone 19 between the sealing

lips

53, 54.

lt is not important whether the roller 5 rotates in the same direction or in the opposite direction as screen 1. It is a feature of this embodiment that the roller 5' does not contact the rotary screen 1, this being attained by the position of roller 5' in the squeegee box 43. The sealing of the squeegee box 43 with rotary screen 1 is effected by sealing

lips

53, 54, which are pressed onto the wall of the screen by means of support means 62 of magnetizable material positioned at the bottom If the squeegee box. The support means are attacted by the effect of the elctromagnets 8, whereby the squeegee box 43 and the sealing

lips

53, 54 are drawn toward the rotary screen 1. The dye which passes sealing lip 54 is removed by squeegees or

doctor blades

55 and 56. By means of plane 57 linked to the squeegeed 55, the dye removed from the interior of screen 1 is supplied to the supply 15 of the squeegee box 43. The dye removed from the outside of the screen by the squeegee 56 is removed through a channel 58.

The squeegee device according to the invention in general as well as to the shown embodiments in particular are not limited to the application in rotary screens of rotary screen printing machines. Such squeegee devices can also be used with flat screens or even for applying a liquid or viscous compound without the use of screens.

1 claim:

1. A squeegee device for applying liquid, in particular highly viscous liquid, onto the surface of a material,

said device comprising a perforated screen; a rotatable roller squeegee mounted for the application of said liquid onto said material through said screen; and a stationary guide wall member having a concave surface, said guide wall member being mounted such that said concave surface is spaced from and extends substantially parallel to the cylindrical peripheral surface of said roller squeegee, and over the entire length thereof, thereby forming a gap between said roller squeegee and said guide wall member, there being a plane extending through the axis of said roller squeegee and the line formed by the points on said roller squeegee positioned most closely to said screen, said guide wall member being mounted on that side of said plane wherein a point on the cylindrical peripheral surface of said roller squeegee and screen approach each other during movement thereof, the lower edge of said guide wall member being positioned between said roller squeegee and said screen; whereby said liquid is conveyed, on rotation of said rollr squeegee, through said gap towards the surface of the material and the pressure of said liquid in said gap is increased.

2. A squeegee device as claimed in claim 1, wherein said guide wall member is displaceably mounted for varying the width of said gap.

3. A squeegee device as claimed in claim 1, wherein the longitudinal lengths of said roller squeegee and said guide wall member are substantially equal, said guide wall member having plane surfaces transverse to the longitudinal length thereof at each of its opposite ends; and further comprising a resilient cylindrical ring attached to each opposite end of said roller squeegee and coaxial thereto, the outer diameters of said rings being greater than the diameter of said roller squeegee, said rings contacting said transverse plane surfaces of said guide wall member, thereby closing the opposite ends of said gap, and forming a sliding seal with said plane surfaces upon rotation of said roller squeegee.

4. A squeegee device as claimed in claim 1, wherein the longitudinal lengths of said roller squeegee and said guide wall member are substantially equal, said guide wall member having plane surfaces transverse to the longitudinal length thereof at each of its opposite ends; and further comprising a sealing ring attached to each opposite end of said roller squeegee and coaxial thereto, a frustroconical sealing lip extending from the outer surface of each of said rings towards the respective one of said transverse plane surfaces thus laterally closing said gap and forming a sliding seal with said plane surfaces upon rotation of said roller squeegee.

5. A squeegee device as claimed in claim 1, wherein the cross section of said guide wall member has a rounded upper edge and two concave outer surfaces tapering to a pointed lower edge.

6. A squeegee device as claimed in claim 1, further comprising a squeegee box having four substantially vertical walls, said roller squeegee being mounted in said squeegee box, one of said vertical walls forming said guide wall member.

7. A squeegee device as claimed in claim 6, further comprising a second roller mounted in said squeegee box above said roller squeegee, said second roller being rotated by a variable speed drive.

8. A squeegee devices as claimed in claim 7, wherein said second roller is rotated in a direction opposite to that of said roller squeegee.

9. A squeegee device as claimed in claim 7, wherein a second of said vertical walls of said squeegee box forms a second guide wall member designed to define a second gap between said second roller and said second guide wall member,'liquid being conveyed through said second gap to the entrance of said gap between said second roller squeegee and said guide wall member on rotation of said second roller.

10. A squeegee device as claimed in claim 9, wherein said second gap is'narrower than said gap between said roller squeegee and said guide wall member.

Claims

1. A squeegee device for applying liquid, in particular highly viscous liquid, onto the surface of a material, said device comprising a perforated screen; a rotatable roller squeegee mounted for the application of said liquid onto said material through said screen; and a stationary guide wall member having a concave surface, said guide wall member being mounted such that said concave surface is spaced from and extends substantially parallel to the cylindrical peripheral surface of said roller squeegee, and over the entire length thereof, thereby forming a gap between said roller squeegee and said guide wall member, there being a plane extending through the axis of said roller squeegee and the line formed by the points on said roller squeegee positioned most closely to said screen, said guide wall member being mounted on that side of said plane wherein a point on the cylindrical peripheral surface of said roller squeegee and screen approach each other during movement thereof, the lower edge of said guide wall member being positioned between said roller squeegee and said screen; whereby said liquid is conveyed, on rotation of said rollr squeegee, through said gap towards the surface of the material and the pressure of said liquid in said gap is increased.

9. A squeegee device as claimed in claim 7, wherein a second of said vertical walls of said squeegee box forms a second guide wall member designed to define a second gap between said second roller and said second guide wall member, liquid being conveyed through said second gap to the entrance of said gap between said second roller squeegee and said guide wall member on rotation of said second roller.

10. A squeegee device as claimed in claim 9, wherein said second gap is narrower than said gap between said roller squeegee and said guide wall member.