US3109365A

US3109365A - Stenciling apparatus

Info

Publication number: US3109365A
Application number: US164256A
Authority: US
Inventors: William M Karlyn
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-01-04
Filing date: 1962-01-04
Publication date: 1963-11-05
Anticipated expiration: 1980-11-05

Description

Nov. 5, 1963 w. M. KARLYN 3,109,355

STENCILING APPARATUS Filed Jan. 4, 1962 4 Sheets-Sheet 1 FIG. I

DER 2 o BLE 5 4 SOL.V 22.

INVENTOR. WILLIAM M. KARLYN Z- W 2 WM ATTORNEYS 1963 w. M. KARLYN 3,109,365

STENCILING APPARATUS Filed Jan. 4, 1962 4 Sheets-$heet 2 FIG. 2

FIG. 3

we" INVENTOR'.

WILLIAM M. KARLYN BY I +-4 ATTORNEYS Nov. 5, 1963 w. M. KARLYN 3,109,365

STENCILING APPARATUS Filed Jan. 4, 1962 4Sheets-Sheet 5 FIG. 4

INVENTOR. WILLIAM M. KARLYN ATTORNEYS Nov. 5, 1963 w. M. KARLYN 3,109,365

STENCILING APPARATUS Filed Jan. 4, 1962 4 Sheets-Sheet 4 M FIG.7

INVENTOR. WILLIAM M. KARLYN ATTORNEYS United States Patent l 3,ltl9,365 STENCILING APPARATUS William M. Karlyn, 69 Orchard Road, Swampscott, Mass. Filed Jan. 4, 1962, Ser. No. 164,256 9 Claims. (Ql. 1ll1--124) This invention relates to stenciling apparatus, and more particularly to an improved apparatus for stenciling curved surfaces of articles, such as flexible plastic bottles, by means of the silk-screen stenciling process.

Stenciling apparatus of the silk-screen type requires means for rotatably supporting the curved surface to be stenciled against one surface of a silk screen, and means such as a squeegee pressed against the opposite face of the screen for forcing paint through the screen to stencil the surface. The squeegee and article are maintained in alignment and in compression with one another as the screen is translated in the plane of its surface between these elements. Various manual and automatic machines for carrying out these functions have been made available, but the manual devices afford very limited production rates, and previously-proposed automatic devices generally utilize complex mechanical linkages and systems for correlating the movements and functions of the various parts. It is the primary object of the present invention to provide an automatic stenciling apparatus which affords a high rate of production and accurate stencil reproduction, but which is of reduced mechanical complexity, and entails a moderate production cost and maintenance expense.

The machine of the present invention is of a type which is capable of stenciling two successive articles upon each complete reciprocation of the silk screen, stenciling one article upon each translation between two terminal positions. To accomplish this result, it is desirable to provide means for raising the squeegee from the screen prior to the attainment of the terminal positions, so that a pool of paint previously placed on the screen may pass under the squeegee into proper juxtaposition for painting a succeeding article upon the return movement to the opposite terminal position. An automatic machine of this kind also requires that a carriage which is arranged to support the article in rolling frictional engagement with the lower surface of the screen, be lowered at the end of each translation from one to another of the terminal positions, to permit removal of a stenciled article and replacement by a succeeding article. Machines previously available have provided complex mechanical interlocks between the elements to produce the necessary correlated cycle of movements of the squeegee, screen, and article carriage. It is a further object of the present invention to provide fully automatic stenciling apparatus which utilizes position-sensor means for transmitting control signals to motive means for correlating the movements of a squeegee, silk screen, and article carriage in a predetermined cycle. It is another object of my invention to provide a simplified machine of the aforementioned type, entailing moderate initial cost and maintenance expense, which at the same time is capable of a high rate of productive output with highly faithful stenciling accuracy.

Further objects and advantages of the invention will become apparent as the following description proceeds.

Briefly stated, according to a preferred embodiment of the invention, I provide a frame adapted to mount a selected silk screen, and mount the frame in a structural support for reciprocation in the plane of the screen between opposite terminal positions defined by adjustable stops attached to the support. A squeegee is mounted pivotally in the support for movement to a lowered position engaging the upper surface of the screen, or to a 2 raised position spaced therefrom. A carriage, which has a fixture adapted to secure a desired article rotatably thereon, is arranged for movement to a raised position for engaging the article surface which is to be stenciled in rolling frictional compression against a lower surface of the screen, or to a lowered position in which an operator may load and remove articles from the carriage. Pneumatic motors or other suitable motive means are provided for actuating these elements between the aforementioned alternate positions.

The elements thus far described are conventional, and my invention resides in a combination therewith of improved means for actuating these elements in a correlated manner to carry out a repeatable stenciling cycle, in which succeeding articles may be stenciled in each translatory movement of the screen between its opposite terminal positions. These means essentially comprise three position sensors arranged to transmit signals to control means for independently actuating the motive means of the screen frame, squeegee, and article carriage. A first position sensor is arranged to be actuated by the carriage in its lowered position, to energize the motive means of the carriage and the squeegee to actuate these elements to their positions engaging the opposite surfaces of the screen, in preparation for the stenciling of m article. The first sensor is preferably delayed in its response by a suitable time-delay switch to afford an operator surficient time to load and unload successive articles, and may be alternately controlled by a manual switch.

A second position sensor is adapted to be actuated by the article carriage upon the attainment of its raised position, to energize the motive means of the screen frame through a suitable control device, to drive the screen from one of its terminal positions toward the opposite terminal position. A pool of paint is applied to the upper surface of the screen in advance of the squeegee, so that during the translation of the frame, the squeegee causes paint to be applied through the silk screen stencil to the surface of the selected article. This surface passes in rolling frictional engagement over the lower screen surface, which is continually subjected to pressure engagement therewith by means of the squeegee, the latter being registered with the stenciled surface at all times.

A third position sensor is adapted to be actuated by stops adjustably secured in spaced relation along the frame in the direction of translation, to reverse the motive means of the bottle and squeegee somewhat in advance of the attainment by the screen of its terminal position. In this manner, the pool of paint flowing over the screen surface against one side of the squeegee is allowed to pass under the squeegee to the opposite side, for flowing over the screen in the opposite direction upon the return translatory movement to the first terminal position for painting a succeeding article. As the third sensor is actuated to displace the squeegee and the carriage from the screen surfaces, the operator may remove the stenciled article from the carriage and replace it with another.

As a further feature of the invention, particularly useful for stenciling collapsible plastic bottles, the carriage bears a movable clamp having a motor for engaging the clamp with the lower end of the bottle, and a bottleinfiating nozzle which is positioned to be engaged in the mouth of the bottle by the clamp. A fourth position sensor is arranged to be actuated by the squeegee in its lowered position engaging the screen, to open a valve which controls a compressed-air supply conduit for the infiator nozzle. The clamp motor is preferably arranged for actuation jointly with the bottle carriage and squeegee motors, so that after a bottle has been loaded, the clamp and nozzle engage and inflate the bottle as it is raised to the screen for stenciling. The inflation effectively stilfens the bottle against the pressure of its engagement with the screen, with the result that a greatly improved reproduction can be obtained by these means.

According to an ancillary feature of the invention, I provide an improved fixture for stenciling articles having flattened oval cross-sections, or large radii of surface curvature. Such articles cannot be conveniently mounted for rotation about the centers of curvature of their major surfaces, because of space limitations; the radius to the ture or virtual center of curvature of the major surfaces may be quite large. It is therefore necessary to provide some more compact means for rolling the article surface in accurate registration with the screen surface, and with at least substantially uniform and equal linear'velocity. To this end, I provide a fixture having a base for interchangeable mounting on the article carriage of the machine, and pivotally mount a shaft on the base for rotationon an axis which is arranged parallel to the plane of the screen and normal to the direction of its reciprocation. A clip adapted to slidably receive an article of the desired form is supported for rotation with the shaft, in a path whose radius is substantially less than the virtual or actual radius of the surface to be stenciled. Although the reduced radius of rotation causes the spacing between the shaft and the surface at its points of contact with the screen to vary, this variation is readily accommodated by the flexibility of the screen. For driving the fixture, a crank arm has one end thereof pivotally secured in the frame for reciprocation therewith, and rotary driving connection with the shaft at its opposite end, which connection provides for lost motion longitudinally of the crank. As will be more fully explained hereinafter, a feature of this fixture is that it may be so designed that the linear velocity of the surface of the oval article remains at least substantially uniform and equal to the uniform rectilinear velocity of the screen, so that registered stenciling may take place and smearing is avoided.

While the specification concludes with claims particularly pointing out the subject matter which I regard as my invention, it is believed that a clearer understanding may be gained from the following detailed description of preferred embodiments thereof, referring to the accompanying drawings, in which:

FIG. l is a schematic and partially pictorial view of the operative elements of the stenciling apparatus;

FIG. 2 is a plan view of the complete apparatus;

FIG. 3 is a sectional view taken along line 33 in FIG. 2, looking in the direction of the arrows;

FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 3, looking in the direction of the arrows, and particularly showing the details of a carriage mechanism;

FIG. 5 is a view in front elevation of a special fixture for articles of oval cross-section;

FIG. 6 is a sectional view taken along line 66 in FIG. 5, looking in the. direction of the arrows;'and

FIG. 7 is a diagram showing the geometric relationship of the elements of the fixture in FIGS. Sand 6.

Referring to FIGS. 1-4, my improved stenciling apparatus is of a type generally comprising a frame 10 arranged to support a silk screen 12 mounted in a base 13; a rubber squeegee 14 arranged to engage an upper surface of the silk screen; and a carriage generally designated 16, for rotatably supporting a selected article to be stenciled, such as a plastic bottle 18, for elevation into engagement with a lower surface of the screen, in vertical alignment with the squeegee. By translating the screen and its supporting frame in either direction of reciprocation in the plane of the screen, and by applying a pool of suitable paint to the upper surface of the screen, a stencil pattern exemplified at 20 may be applied to the surface of the article.

The apparatus is organized about a supporting structure which includes a base cabinet 24 for enclosing certain elements, a series of vertical standards 26, and horizontal transverse braces 23, 29, and 30. A longitudinal bar 32 is provided for stiffening the structure, and a pair of 4 cylindrical guide rods 34 are secured at opposite sides of the

braces

28 and 30 for slidably supporting the screen frame 10 for rectilinear reciprocation in the directions shown by the arrows. The base of the cabinet is accessible through a door 36 attached by means of hinges 37.

Four clamps 38 are secured adjacent the corners of the frame 10 and provided with threaded screws 39 for securing the base 13 of a selected silk screen 12 to the lower surface of the frame. The screen frame 10 has a pair of bars 40 secured to its upper surface in longitudinally-extending relation along its lateral edges, each of which contains a pair of linear ball bushings for slidable engagement with the guide rods 34, so that the frame may be reciprocated in an accurate rectilinear manner and with a minimum of friction. Terminal positions of the frame are preselected according to the length of the stencil 20, and are established by means of adjustable stop rings 42 spaced along the guide rods 34 and secured by set screws 44.

A reciprocable double-acting pneumatic motor 46 is arranged for reciprocating the screen and frame, and is mounted between a bracket 48 secured to an end of the bar 32 by screws 50, and an L-shaped bracket 52 secured to the same bar by screws 54. An actuating rod 56 of the motor 46 is drivingly connected to the bar 40 of the frame, by means of an L-shaped bracket 58 secured by screws 69. Compressed air may be supplied for actuating the motor by means of

conduits

62 and 64 having adjustable throttle valves 66 and 63, respectively, by means of which the rate of movement of the frame may be adjusted to afford optimum stenciling results.

The squeegee 14 is of a conventional type, clamped by means of screw 70 on a T-shaped bracket 72. The squeegee is rotatably supported on a shaft 74 by means of an arm 76 which is adjustably secured in an elongated slot 78 of the bracket by means of a bolt 80, and adjustably mounted on the shaft by a bolt 82 passing through a slit hub 84 at one end of the arm. The shaft 74 is rotatably mounted in suitable bearings pressed into the bar 32 and a cantilever bar 86, which extends longitudinally of the apparatus from the cross bar 28; the shaft is thus rotatable about an axis parallel to the plane of the screen, but normal to its direction of reciprocation. For actuating the squeegee to raised and lowered position, a pneumatic motor 8'3, which has a return spring 5W operable to raise the squeegee when the air pressure is released, is drivingly connected with the shaft 74 by means of a crank arm 92. The crank arm is pivotally connected at 94 to an end of the piston rod 96, and adjustably secured to the shaft by means of a bolt 98 passing through a slit hub 100 formed in the crank arm. The motor is arranged to be supplied with compressed air through a conduit 102 having a needle valve 104 for regulating the rate of movement of the squeegee.

The article-supporting carriage 16 includes a fixture having pairs of rollers 11 2 threadedly engaged on each of a pair of horizontal threaded rods 114, for longitudinal adjustment to accommodate articles of selected sizes for rotatable support thereon, so that the article may be revolved by its frictional engagement with the lower surface of the screen. A base plate 116 of the fixture is detachably secured by means of threaded fasteners 118 upon an upper plate 120 of the carriage, so that various fixtures may be readily interchanged for use with various forms or sizes of articles. The plate 120 is spaced from a lower plate 122 by means of threaded studs 124, secured in adjustable relationship to the lower plate by means of lock nuts 126.

The carriage is mounted for vertical reciprocation to raised or lowered positions on guide rods 128, securedin the plate 122 by nuts 129. The guide rods are slidably received in a pair of bearing bushings (FIG. 4), having linear ball bearings (not shown) for guiding the carriage. A double-acting pneumatic motor 132 is mounted interiorly of the box 24, and a piston rod 134 thereof is drivingly engaged with the carriage by means of lock nuts 136. The motor is actuable in either direction of reciprocation by compressed air supplied through

conduits

138 or 140, having flow-controlling

needle valves

142 and 144, respectively, for regulating the rate of movement of the carriage.

Articles commonly stenciled comprise not only glass or other rigid containers, but also flexible plastic bottles which are not in themselves sufliciently rigid to be stenciled with accurate results or good appearance. I therefore prefer to provide means for clamping a cylindrical article on the fixture and for inflating the article with compressed air, which means at the same time permit the article to rotate freely as the screen translates in a plane tangent to its surface. In the embodiment shown, these means include a clamp 150 mounted on the piston rod 152 of a single-acting pneumatic motor 154 supported at an end of the fixture 11%. The motor is arranged to be actuated by means of compressed air through a conduit 156 to drive the clamp toward the position 150 for clamping the article 13 in place, as it is raised by the carriage toward the position 18'. The clamp 151) is rotatably mounted on the shaft 152 for free rotation of the article. At the opposite end of the fixture 11 an inflating nozzle 161) is rotatably mounted in suitable air-tight bearing means 162 secured in the fixture 110, and arranged to receive a supply of compressed air through a conduit 164. As the bottle is raised toward the position 18', the clamp 150 drives the bottle into sealing engagement with the conical nozzle 151 and compressed air is supplied to inflate the bottle to a rigid position.

For automatic operation of the stenciling elements which have now been described, it is necessary to provide control means to afford an operating cycle in which: an article placed in the fixture 110 is clamped in place as the carriage 1 6 and the supported article rise, and the squeegee 14 lowers, into registered engagement with the opposite surfaces of the screen 12; the screen is driven from a first terminal position, in which it is shown in the drawings, to an opposite terminal position to stencil the article by rolling engagement with the screen; and the squeegee and article carriage are withdrawn from the surfaces of the screen prior to the attainment by the latter of its opposite terminal position, so that a pool of paint resting on the screen is carried under the squeegee into appropriate juxtaposition for stenciling a succeeding article upon a repetition of the cycle in which the screen is returned to the first terminal position.

According to the invention, control means for actuating the

motors

4e, 88, 132, 154, and for controlling the inflating nozzle 161) according to the aforementioned cycle, comprise position-sensor means for transmitting control signals, which, in the preferred embodiment, include: a first micro-switch 1711 of a momentary-contact normallyopen type, a second micro-switch 172 of a maintainedcontact or toggle type, which is closed and opened upon alternate actuations; and a toggle linkage generally designated 174 and arranged to open a poppet valve 176. As shown, the system further includes a fourth position-responsive sensor, comprising a micro-switch 178 of a momentary-contact normally-open type, having an actuating button 179, which is utilized for regulating the bottle inflater 160, and may be omitted where the articles to be stenciled are of a sufliciently rigid construction not to require inflation.

The switch 170 is connectable to one lead of a suitable power source by a lead 18), through an adjustable timedelay switch 182, in one position of a double-pole doublethrow switch 183. The switch 170 is arranged to be actuated by the article carriage 16 in its lowered position shown in the drawings, by means of a bracket 184 attached to a cross arm 186, which is in turn secured to the lower ends of the guide rods 128. An adjustment screw 188 engages the switch button 19% for energization of a solenoid valve 191 through a lead 192 to trigger the apparatus. In an alternate position of the switch 183, overcenter from a central de-energized position, the valve 191 may be directly energized by a foot-operated switch 181 through a lead 193. The time-delay switch is utilized for automatic repetition of the operation, and the foot switch for manually-controlled operation.

Compressed air for actuating the apparatus is supplied from a suitable source through a branched conduit 194, having three branches 1%, H7, and 19-8, in which pressure-regulating valves 200 are arranged to afford suitable pressures for the various motors. If desired, an air filter and oiler (not shown) may be interposed in the conduit in position to condition air supplied to the motors by branch conduit-s 1% and 198. The branch conduit 19% supplies a. bleeder-type two-way control valve 202, which is arranged to supply air from the branch conduit 198 alternatively to either of the

conduits

138 or 140 of the motor 132, and to exhaust that one of the motor conduits which is not subject to actuating pressure through an exhaust outlet 204. The valve 202 includes control means which are actuable by the release of air through an exhaust conduit 2%, to supply air to the conduit 138 for raising the carriage 16; and are alternatively actuable by the release of air through an exhaust conduit 2% and the poppet valve 176, to supply air to the conduit 144i and thus lower the carriage. The exhaust conduit 2% is controlled by the solenoid valve 192, so that as the switch 17% energizes the solenoid, the valve 2412 supplies air to the motor 132 and the bottle carriage is raised to carry a bottle 18, previously positioned on the fixture into engagement with the screen.

The conduit 13% is branched at 210' to communicate with the conduit lit-2 of the squeegee-actuating motor 88, and the clamp-actuating motor 154, so that the squeegee is actuated to engage the upper surface of the screen concurrently With the actuation of the carriage to engage the bottle with the lower surface of the screen, and clamping engagement of the bottle with the nozzle 160. The strokes of the

motors

38 and 132 are preferably so related that the squeegee first engages the screen, to limit seepage of paint to the reverse side thereof as the article strikes the screen. At the same time, the rising arm 92 of the squeegee actuates the switch 173, which energizes a solenoid valve 212 through a lead 214 to communicate the branch conduit 197 with the infiater nozzle 16%) through its conduit 164, so that the bottle is firmly inflated as it engages the screen. The mechanism is now prepared to commence a stenoiling operation by applying paint from a pool lying on the supper surface of the screen, through the stencil pattern to the bottle.

As the carriage attains its raised position, an adjustment screw 216 threaded on the bracket 1S4 strikes an actuating button 218 of the switch 172, to energize a solenoid valve 220 through a lead 222. The valve 22% is of a doublesolenoid bleeder type, such that upon each successive energization, communication is alternatively established between the branch conduit 1% and either of the

conduits

62 or 64. The valve also connects the unpressurized one of conduits s2 and 64 with an exhaust outlet 224, so that the motor 46 is tree to drive the screen to an opposite terminal position under the applied pressure. As the screen and frame translate relative to the squeegee and the stenciled article, paint is forced in a well-known manner through the pattern 2% onto the surface of the article 18, which rotates in registration with the pattern across the surface of the screen.

In order to provide for stenciling a succeeding article upon the return stroke of the screen to its original terminal position, the position-responsive sensor means 174 is arranged for actuation prior to the attainment by the frmie of either of its terminal positions. The sensor 174 includes a. roller 23% which rolls on a T-section track 232 formed along the upper surface of the bar 40. A pair of stops 23 are slidably mounted on the track, and secured in adjusted spaced positions by means of set screws 236. The roller 230 is pivotally mounted in one end of a link 2138, which is in turn pivoted on a pin 240 in the end of a link 242. An arm 244, having an adjustment screw 246 threaded in a free end thereof for actuating the poppet valve 176, is secured to an end of a shaft 248, and the link 242 is secured to the opposite end of the shaft to form a rigid bell-crank, which is pivotally mounted by means of a bearing bushing 25% in the cantilever bar 86'. These means form a toggle linkage, in which the length of link 238 is greater than the vertical spacing between the axle 248 and the track 232; consequently, the link 2315 is canted in either direction from the vertical as the roller 230 passes along the track 232. However, upon the roller 230 striking one of the stops 234, the linkage is driven through its over-center position to reverse the angular relationship between the link 2'38 and the track 232, and therefore momentarily rotates the bell-

crank including links

242 and 244 in a counterclockwise direction. The screw 246 is so adjusted that the counterclockwise movement causes it to strike and depress a ball 252 forming the valve element of the poppet valve 176, against the bias of a compression spring 254, momentarily exhausting the conduit 208 to reverse the valve 292. A stop 256 is secured on the cantilever bar 86, for limiting the return clockwise rotation of the bell-crank upon the return translation of the screen frame.

Reversal of the valve 202 prior to the end of the stroke of the screen causes the motor 132 to lower the carriage 16 and the article 18 from the screen, and at the same time, the exhaustion of air pressure by the valve from the

conduits

210, 156, and 102 causes the motor .154 to release the clamp 150, and the motor 88 to raise the squeegee 14 from the screen surface. As the squeegee rises, a pool of paint hitherto forced over the surface of the screen in advance of the squeegee, passes beneath the squeegee into position for riding against the opposite face of the squeegee as the screen returns to itsoriginal terminal position and a succeeding article is stenciled. Raising of the squeegee also de-energizes the valve 221 by releasing the contact button 179 of the switch 173, to discontinue the supply of air to the infiateir nozzle 160 during the removal of the stenciled article and replacement by a succeeding article. The cycle which has been described is repeated upon the return stroke of the screen, and is initiated by the reengagement of the switch 170 by the lowered carriage, after a delay established by the switch 182.

It will be apparent to those skilled in the art that while pneumatic motors and solenoid-controlled valves have been shown in the preferred embodiment of the machine which has been described, the selection of motive means, position-responsive sensors for transmitting control signals, and control means for energizing the motive means in response to the control signals, may include various types of electrical, pneumatic, hydraulic, or other means adapted to perform these functions.

The fixture which has been shown and described is suitable for stenciling articles having circular cylindrical surfaces and which may be conveniently rotated about the axis of curvature of such surfaces, but alternate fixtures are desirable for stenciling of articles having large radius surface curvatures, such as flattened oval-section articles. A fixture suitable for this purpose is shown in FIGS. 5-7. This fixture is organized on a base plate 270, suitable for mounting on the carriage 16 of the previously-described apparatus, in place of the fixture 110. The base plate is formed with bolt holes 272 for this purpose. A shaft 274 is pivotally mounted on the base by means of a pair of bearing bushings 276 mounted in bosses 278 aflixed to the base plate. The axis S of the shaft 274 is arranged, when the fixture is attached to the carriage 16, parallel to the plane of the 7 screen 12 but normal to the directions of reciprocation 2:; flattened oval article, such as a bottle 282, in upstanding opposed

brackets

284 and 286 thereof, which are secured by means of screws 288. The bracket 284 has formed at its rearward end an ear 2% for engaging the bottom end of the bottle 282 as the latter is longitudinally inserted between the brackets. The brackets are shaped to conform to the contours of lateral portions of the particular article to be stenciled, for securely positioning the article. The clip 28th is mounted for rotation with the shaft 274 about the axis S of the latter, by means of a rod 292 threaded into the clip and into a split clamp 294, secured in adjusted position on the shaft by a machine screw 296.

Inasmuch as the bottle 2%2 is mounted in a statically unbalanced manner on the shaft 274, it is necessary to provide driving means, other than frictional rolling engagement between the bottle and the screen, for revolving the surface of the bottle in registered relation to the screen, thereby to avoid relative sliding movement between the screen and the article which would smear the stencil. For this purpose, I drivingly connect the shaft 274 with one of the bars 44) on the screen frame 10 by means of a linkage, which includes a crank arm 298 of which a lower end is slidably received in a linear bearing bushing 300 secured to the shaft by means of an L.- shaped crank 302. At its opposite end, the crank arm 298 is formed with a boss 304 pivotally receiving a pivot pin 396, which is threaded in one end of a depending fixed arm 368 having a stud 31MB threaded into the bar 40 at its opposite end. It will be apparent that as the screen reciprocates in a plane which is normal to the plane of FIG. 5, it will produce rectilinear motion of the pivot pin 306, which is translated by the crank arrn 298 through the lost-motion connection of bushing 3M into rotary motion of the shaft 274 and the bottle 232.

Referring to FIG. 7, the geometric relationships of the moving parts of the fixture are schematically illustrated in three positions in which the axis P of the pin 306, passing from a vertically aligned relation to the shaft axis S in position P translates rectilinearly in increments of equal length to positions P and P,, thus producing rotary motion of the shaft, the clip, and the supported bottle 282 through corresponding angular increments which are of decreasing value, angle a being greater than angle ,8. At the same time, the screen translates rectilinearly through equal increments X X,, X,,X,, each of which points on the screen successively passes between the squeegee 14 and the surface 282 in this movement. Since the angle or exceeds the angle 6, the arc length of the incremental movements of the center C of the bottle are unequal, arc length C C,, being greater than arc length C,C,. If the radius of the surface 282 were equal to the radius S-C about which the center of the bottle revolves, it will be apparent that the linear velocity of the bottle surface would vary and would in fact decrease as the bottle center passed from its vertical position C so that relative sliding movement and resulting smearing would occur between the screen and the bottle surface. However, the radius R, about which'the bottle surface revolves, increases progressively, as shown by the radii R, R,,, R, to the successive points of contact X X, with the screen surface. Since the linear velocity of the bottle surface is equal to the product of the angular velocity and the radius about which the surface points revolve, and since the radius R R,,, R, is increasing while the angular velocity decreases between these respective positions, these variations may be designed to offset one another and to produce a uniform linear velocity of the bottle surface. The rate of change of the angular velocity is fixed by the geometry of the device; however, by varying the designed length of the rod 292, the radius S-C between the centerlines of the shaft 274 and the article 282 may be selected such that, for a given form of bottle surface, the linear velocity of the bottle surface may be maintained at least substantially uniform and equal to the linear velocity of the screen. It will also be apparent that the angular relationship between the crank arm 2% and the rod 292 may be altered by angular threading adjustment of the arm 308 relative to the frame 10. A lock nut 312 is provided to secure the arm 398 in the adjusted position. A sufficiently close approximation may be made in actual practice to produce highly satisfactory results even with articles which have curved surfaces of non-circular form.

While I have described and illustrated preferred embodiments of my invention by Way of illustration, it will be apparent to those skilled in the art that various chan es and modifications may be made therein without departing from the true spirit and scope of the invention, which I therefore intend to define in the apended claims without limitation to specific details of the illustrative embodiments.

What I claim is:

1. Apparatus for stenciling a curved surface of an article, comprising, in combination:

a frame adapted to support a plane silk screen and mounted for reciprocation in the plane of the supported screen; first motive means for reciprocating said frame to first and second terminal positions;

a carriage adapted to rotatably support an article to be stenciled for registered rolling engagement with a lower surface of said screen, said carriage being mounted for reciprocation to a raised position engaging the supported article with said lower surface of said screen and to a lowered position spacing the article from said screen; second motive means for reciprocating said carriage;

squeegee means mounted for movement to a lowered position engaging an upper surface of said screen opposite the article, and to a raised position spaced from said screen; third motive means drivingly connected with said squeegee means for movement thereof between said raised and lowered positions;

first position-responsive sensor means actuable by said carriage in said lowered position for actuating said second and third motive means to raise said carriage and lower said squeegee means for engaging said surfaces of said screen;

second position-responsive sensor means actuable by said carriage in said raised position for actuating said second motive means to drive said frame from either of said terminal positions to the other terminal position for stcnciling an article;

and third position-responsive sensor means actuable by said frame as said frame approaches said other terminal position to reverse the actuation of said first and second motive means to lower said carriage for removal of the stenciled article and insertion of a succeeding article, and to raise said squeegee means from said screen prior to said frame reaching said other terminal position for movement of a pool of paint resting on said screen under said squeegee cans for stenciling the succeeding article upon the return movement of said frame to the original terminal position.

2. A stenciling apparatus as recited in claim 1, to-

gether with a fixture for supporting an article on said carriage, said fixture comprising;

a clip for securing an article having a curved surface to be stenciled, a shaft pivotally mounted in said carriage on an axis parallel to the plane of the screen and normal to the direction of reciprocation thereof, said clip being supported on said shaft for rotation therewith, and a crank arm attached to said frame and reciprocable therewith in said plane,

said crank arm having a lost-motion connection with said shaft for pivotal movement of said clip and the supported article in syuchronism with the plane reciprocating movement of said frame for registered stenciling of said surface of said article by means of a stencil design in said screen.

3. A stenciling apparatus as recited in claim 1, together with a clamp mounted on said carriage for releasably securing an article rotatably thereon, and fourth motive means for actuating said clamp;

said first and said third sensor means being connected for actuating said fourth motive means jointly with said second and third motive means, to engage said clamp with the article when said carriage is raised and to disengage said clamp as said frame approaches said other tenminal position and the stenciling of the article is completed.

4. A stenciling apparatus as recited in claim 3, together with an inilater for engagement in an opening in a hollow article supported in said carriage;

said infiater comprising a nozzle and a conduit for connection to a source of compressed air for inflating said article, said clamp being arranged to sealingly engage said article against said nozzle;

a valve interposed in said conduit for controlling flow of compressed air to said nozzle;

and a fourth position-responsive sensor actuable by said squeegee means in said lowered position thereof to energize said valve to an open position for inflating said article, said valve closing said conduit upon deactivation of said fourth sensor in said raised position of said squeegee means.

5. Apparatus for stenciling a curved surface of an article, comprising, in combination;

a frame adapted to support a plane silk screen and mounted for reciprocation in the plane of the supported screen, first motive means for reciprocating said frame to first and second terminal positions;

first signal-responsive control means for reversibly energizing said first motive means;

a carriage adapted to rotatably support an article to be stenciled for registered rolling engagement with a lower surface of said screen, said carriage being mounted for reciprocation to a raised position engaging the supported article with said lower sunface of said screen and to a lowered position spacing the article from said screen; second motive means for reciprocating said carriage;

squeegee means'mounted for movement to a lowered position engaging an upper surface of said screen opposite the article, and to a raised position spaced from said screen; third motive means drivingly connected with said squeegee means for movement thereof between said raised and lowered positions;

second signal-responsive control means for reversibly energizing said second and third motive means jointly;

first position-responsive sensor means actuable by said carriage in said lowered position for transmitting a signal to said second control means for energizing said second and third motive means to raise said carriage and lower said squeegee means for engaging said surfaces of said screen;

second position-responsive sensor means actuable by said carriage in said raised position for transmitting a signal to said first control means to energize said second motive means to drive said frame from either of said terminal positions to the other terminal position for stenciling m article;

and a third position-responsive sensor means actuable by said frame as said frame approaches said other terminal position for transmitting a signal to said second control means to energize said second and third motive means to lower said carriage for removal of the stenciled article and insertion of a succeeding article, and to raise said squeegee means from said screen prior to said frame reaching said other terminal position for movement of a pool of paint resting on said screen under said squeegee means for stenciling the succeeding article upon the return movement of said frame to the original terminal position.

6. Apparatus for stenciling curved surfaces of articles,

comprising, in combination; 7

a frame for supporting a plane silk screen and mounted for reciprocation in the plane of the screen between terminal positions; a first reciprocable motor drivingly connected with said frame for reciprocation thereof between two terminal positions;

a carriage adapted to rotatably support an article to be stenciled for registered rolling engagement with a lower surface of said screen, said carriage being mounted for reciprocation between a raised position for engaging the article supported therein with said lower surface of said screen and to a lowered position spacing the article from said screen; a second reciprocable motor for reciprocating said carriage;

squeegee means supported for movement to a lowered position engaging said screen on an upper surface in alignment with a surface portion of said article engaging the lower surface of the screen, and to a raised position spaced from said screen; a third reciprocable motor drivingly connected with said squeegee means for movement thereof between said raised and lowered positions;

first position-responsive sensor means arranged for actuation by said carriage in said lowered position to generate a signal to actuate said second and said third motors for raising said carriage and lowering said squeegee means for engaging said screen;

second position-responsive sensor means arranged for actuation by said carriage in said raised position to reverse said first motor for driving said frame from one of said terminal positions to the opposite terminal position for stenciling said article;

and a third position-responsive sensor means including an over-center toggle linkage and spaced-apart stops afiixed to said frame for actuating said sensor means when said frame approaches either of said terminal positions, to reverse said second and third motors to lower said carriage and raise said squeegee means upon completion of stenciling of said article, but prior to the completion of the frame movement toward said opposite terminal positions, whereby a pool of paint resting on said screen will pass freely under said squeegee means for cooperation with said squeegee to stencil a succeeding article upon a return stroke of said frame to said one terminal position.

7. Apparatus for stenciling curved surfaces of articles comprising, in combination;

first signal-responsive control means for reversibly energizing said first motor;

squeegee means supported for movement to a lowered position engaging said screen on an upper surface in alignment with a surface portion of said article engaging the lower surface of the screen, and to a raised position spaced from said screen; a third reciprocable motor drivingly connected with said squee- 1.2 V gee means for movement thereof between said raised and lowered positions;

second signal-responsive control means for reversibly energizing said second and third motors jointly;

first position-responsive sensor means arranged for actuation by said carriage in said lowered position to transmit a signal to said second control means for energizing said second and said third motors for raising said carriage and lowering said squeegee means for engaging said screen;

second position-responsive sensor means arranged for actuation by said carriage in said raised position to transmit a signal to said first control means for reversing said first motor to drive said frame from one of said terminal positions to the opposite terminal position for stenciling said article;

and a third position-responsive sensor means including an over-center toggle linkage and spaced-apart stops affixed to said frame for actuating said sensor means when said frame approaches either of said terminal positions, to reverse said second and third motors to lower said carriage and raise said squeegee means upon completion of stenciling of said article but prior to the completion of the frame movement toward said opposite terminal position, whereby a pool of paint resing on said screen will pass freely under said squeegee means for cooperating with said squeegee to stencil a succeeding article upon a return stroke of Said frame to said one terminal position.

8. A fixture adapted for use in apparatus for stenciling a curved surface of an article, of the kind which comprises a frame for supporting a plane silk screen for reciprocation in the plane of the screen, a carriage adapted to mount a fixture for rotatably supporting the curved surface of the article in frictional engagement with a lower surface of the screen, and squeegee means engageable with an upper surface of the screen for stenciling the article as the frame is reciprocated, said fixture comprising;

a base, a shaft pivotally mounted in said base on an axis arrangeable parallel to the plane of the screen and normal to the direction of reciprocation of the frame, a clip adapted to receive a selected article for stenciling and supported on said shaft for rotation therewith in a path whose radius is less than the virtual radius of the curved surface of the article .to be stenciled, and a crank arm having one end adapted to be pivotally secured in said frame for reciprocation therewith in said plane, said crank arm having a lost-motion connection with said shaft for pivotal movement of said clip and the supported article in synchronism with the plane reciprocating movement of said frame, for registered movement of said surface of said article with a stencil design in said screen.

9. A fixture as recited in claim 8, in which the said path of rotation of said clip is of a radius selected to compensate for the decreasing angular velocity of said clip as it is moved from a vertical relationship to said shaft by uniform rectilinear translation of said frame, such that the linear velocity of the surface of said selected article at points successively engaging said screen is maintained substantially uniform and equal to said linear velocity of said frame.

References Cited in the file of this patent UNITED STATES PATENTS 2,116,466 Secoy May 3, 1938 2,301,119 Holbrook Nov. 3, 1942 2,556,657 Martin June 12, 1951 2,918,866 Reed Dec. 29, 1959 2,972,943 Velonis Feb. 8, 1961

Claims

1. APPARATUS FOR STENCILING A CURVED SURFACE OF AN ARTICLE, COMPRISING, IN COMBINATION: A FRAME ADAPTED TO SUPPORT A PLANE SILK SCREEN AND MOUNTED FOR RECIPROCATION IN THE PLANE OF THE SUPPORTED SCREEN; FIRST MOTIVE MEANS FOR RECIPROCATING SAID FRAME TO FIRST AND SECOND TERMINAL POSITIONS; A CARRIAGE ADAPTED TO ROTATABLY SUPPORT AN ARTICLE TO BE STENCILED FOR REGISTERED ROLLING ENGAGEMENT WITH A LOWER SURFACE OF SAID SCREEN, SAID CARRIAGE BEING MOUNTED FOR RECIPROCATION TO A RAISED POSITION ENGAGING THE SUPPORTED ARTICLE WITH SAID LOWER SURFACE OF SAID SCREEN AND TO A LOWERED POSITION SPACING THE ARTICLE FROM SAID SCREEN; SECOND MOTIVE MEANS FOR RECIPROCATING SAID CARRIAGE; SQUEEGEE MEANS MOUNTED FOR MOVEMENT TO A LOWERED POSITION ENGAGING AN UPPER SURFACE OF SAID SCREEN OPPOSITE THE ARTICLE, AND TO A RAISED POSITION SPACED FROM SAID SCREEN; THIRD MOTIVE MEANS DRIVINGLY CONNECTED WITH SAID SQUEEGEE MEANS FOR MOVEMENT THEREOF BETWEEN SAID RAISED AND LOWERED POSITIONS; FIRST POSITION-RESPONSIVE SENSOR MEANS ACTUABLE BY SAID CARRIAGE IN SAID LOWERED POSITION FOR ACTUATING SAID SECOND AND THIRD MOTIVE MEANS TO RAISE SAID CARRIAGE AND LOWER SAID SQUEEGEE MEANS FOR ENGAGING SAID SURFACES OF SAID SCREEN; SECOND POSITION-RESPONSIVE SENSOR MEANS ACTUABLE BY SAID CARRIAGE IN SAID RAISED POSITION FOR ACTUATING SAID SECOND MOTIVE MEANS TO DRIVE SAID FRAME FROM EITHER OF SAID TERMINAL POSITIONS TO THE OTHER TERMINAL POSITION FOR STENCILING AN ARTICLE; AND THIRD POSITION-RESPONSIVE SENSOR MEANS ACTUABLE BY SAID FRAME AS SAID FRAME APPROACHES SAID OTHER TERMINAL POSITION TO REVERSE THE ACTUATION OF SAID FIRST AND SECOND MOTIVE MEANS TO LOWER SAID CARRIAGE FOR REMOVAL OF THE STENCILED ARTICLE AND INSERTION OF A SUCCEEDING ARTICLE, AND TO RAISE SAID SQUEEGEE MEANS FROM SAID SCREEN PRIOR TO SAID FRAME REACHING SAID OTHER TERMINAL POSITION FOR MOVEMENT OF A POOL OF PAINT RESTING ON SAID SCREEN UNDER SAID SQUEEGEE MEANS FOR STENCILING THE SUCCEEDING ARTICLE UPON THE RETURN MOVEMENT OF SAID FRAME TO THE ORIGINAL TERMINAL POSITION.