US3106890A

US3106890A - Frame printing machine

Info

Publication number: US3106890A
Application number: US167228A
Authority: US
Inventors: Schmitt Jean
Original assignee: Alsacienne de Constructions Mecaniques SA
Current assignee: Alsacienne de Constructions Mecaniques SA
Priority date: 1961-01-26
Filing date: 1962-01-19
Publication date: 1963-10-15
Anticipated expiration: 1980-10-15

Description

11 Sheets-Sheet 1 Filed Jan. 19, 1962 1| ii, Il

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11 Sheets-Sheet. 3

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, .Sv v S @mmm Oct. 15, 1963 J. scHMrr-r` Fmm PRINTING MACHINE Filed Jan. 19, 1962 Oct.'15, 1963 J. SCHMITT 3,106,890

l FRAME PRINTING .MACHINE Filed Jan.v 19, 1962 11 Sheets-Sheet, 4

Oct. 15, 1963 J. scHMlYT-r 3,106,890

FRAME PRINTING MACHINE Filed Jan. 19, 1962 l1 Sheets-Sheet, 5

FIG 5 Oct. 15, 1963 J. scHMrrT FRAME PRINTING MACHINE 11 Sheets-Sheet, 6

Filed Jan. 19, 1962 lll/lll g oct. 15, 1963 J. SCHMITT 3,106,890

FRAME PRINTING MACHINE Filed Jan. 19, 1962 11 Sheets-Sheet.. 7

11 Sheets-Sheetl 8 Filed Jan. 19, 1962 Oct. 15, 1963 J. scHMl-r'r v3,106,890

FRMIIE PRINTING MACHINE Filed Jan. 19, 1962 11 sheet-,s-sneet e vn ww um 3 2 ocr. 15, 1963 J. SCHMITT 3,106,890

FRAME PRINTING MACHINE Filed Jan. 19, 1962 11 Sheets-Sheet. 10

39 59 Vlll Oct. 15, 1963 I `.1. scHMlTT 3,106,896

FRAME PRINTINGl MACHINE United States Patent O 3,166,896 FRAME PRINTING MACHINE .lean Schmitt, Mulhouse, Haut-Rhin, France, assigner to Societe Alsacienne de Constructions Mecaniques, Mulhouse, Haut-Rhin, France, a company of France Filed Ian. 19, 1962, Ser. No. 167,223 Claims priority, application France Ilan. 26, 1961 1S Claims. (QI. itil-2.3)

This invention relates to a process of printing patterns upon sheet materials, especially textile fabrics, sometimes known as the Lyons printing process. For the purposes of this specification this process, as presently 1detned, will be termed a frame printing process and machines for carrying it out will be termed frame printing machines.

In the `frame printing process as herein delined, a length of the sheet material, eg. fabric, to be printed on is supported in lat condition upon a work table to the surface of which the material is firmly attached as by a suitable adhesive bond. yA carriage is supported for movement lengthwise of the table above the worl` material and means, including stops adjustable longitudinally of a bar extending alongside the table, are provided for arresting the carriage at each of a number of preset printing positions along the table corresponding to the positions on the work material at which a pattern is to be printed. The carriage supports :a pattern frame including a stencil of :the desi-red pattern to be printed, the `frame being movable `on the carriage between a raised position and a lowered printing position in which the stencil engages the surface of the work on the table. With the carriage positioned at a ydefinite lone of the preset positions along the table, the carrier frame is lowered to apply the stencil to the work, printing uid of a desired colour is applied through the stencil, and a squeegee is traversed across the stencil to spread the iluid over the work in the desired pattern as determined by the stencil. '['hen the frame carrier` is returned to its raised position and the carriage can be advanced to a further one of its preset positions. In this manner part lor all of fthe surface of the work can be printed lwith a desired pattern. The printed patterns may of course include more than one colour by providing separate stencils for each colour `desired andy repcating the above operations with each stencil.

Heretofore frame printing machines for carrying out the process described have been operated by and large manually. rIhat is, displacement `ot the carriage along the table, raising and lowering of the frame carrier, and traverse of the squeegee, have had to be elected under ianual control and using muscular force or possibly with some power assistance. With increased consumer demand for printed textile and other sheet articles, such manual 'operation becomes wasteful of time and labour. Moreover, the vagaries of muscular activity which necessarily accompany manual opera-tion are reflected as a lack of uniformity in ythe printed articles. For instance the pressure of application of the squeegee and hence the depth of colour is likely to vary from one print to another.

It is hence an object of -this invention to provide an automatic frame printing machine. Other objects are included in the more or Iless obvious benetits that such automaticity will bring with it, including greatly increased production rate, reduced labour, heightened reliability and uniformity in the nished work. Other and more specific objects and advantages will appear from the description to follow.

According to a principal aspect of the invention there is provided a -frame printing machine which comprises an elongate table adapted to receive a sheet of material ICC to be printed on, a main carriage supported for longitudinal :displacement over the table, a frame carrie-r having a printing pattern frame and supported on said carriage for movement between a printing position in engagement with said material on the table and a raised position, a squeegee assembly supporte-d lfor horizontal traversing `displacement across said frame carrier when in printing position to apply a printing substance through said pattern to said material, and control means for automatically imparting to said carriage, frame carrier and squeegee assembly a cyclic sequence of displacements including: advancing the carriage in steps to a series of pre-set positions spaced along the table; at each step moving the frame carrier to printing position, traversing the squeegee assembly across Ithe `frame carrier, and moving the frame carrier back to raised position; and returning the carriage to an initial position on the table atter a last step of advance.

An exemplary embodiment of the improved machine as well as some modilications therein will now be described for illustrative but not restrictive purposes with refe-rence to the accompanying drawings, wherein: Y

FIG. l is a side view of the improved frame printing machine with the table broken away on either side of the carriage because of dnawing space limitations;

FIG. 2 is a plan View corresponding to FlG. l, with other parts broken away;

FIG. 3 is a vertical section ton line III- III of FIG. l;

FIG. 4 is a larger scale view, partly in section ion line IV-lV of FIG. l, illustrating a cam device used for imparting up and down movement to the frame carrier;

FIG. 5 is a large-scale view in vertical section on line V--V of FIG. 2, illustrating the squeegee assembly and related pants of the -frame carrier;

FIG. 6l is a partial view corresponding lt-o FIG. 3 but on an enlarged scale and illustrating a modiied construction of the trame carrier;

FIG. 7 is a plan view corresponding to FIG. 6, with parts broken away;

FIGS. 8, 9 and lO illustrate different operating conditions of an electromagnetic carriage arrester unit also shown in FIG. 1;

FlG. l1 is an electric circuit diagram showing the control circuits of the three electric motors powering the three main components of the machine;

FIGS. 12a and 12b, when connected at the vertical chain line, form a general circuit diagram of the control circuits of the machine; and

FIG. 13 is a partial diagram relating to ya modication of part of FIG. 12b.

yReferring to the drawings, the limproved frame printing machine shown comprises a table 101 supported on legs 1oz at an elevation above the ground. A main carriage 1113 is supported on the :table for longitudinal displacement lover it through means later ldescribed and carries a pattern frame carrier 104. A squeegee-carr-ier is supported on the frame carrier 104 for longitudinal traversing movement over it. The machine further comprises electromechanical control equipment later dcscribed in detail and operative to impart cyclically to the aforementioned components the following automatic sequence ci `displacements in timed relationship to one another: Step-by-step advance of carriage 103 along the table; downward then upward reciprocation of the frame carrier 1&4 at each step; and quick return of the carriage 193 to its initial position after it has beenl advanced a number of steps to bring it as far as an end point of the work material bonded to the surface of table 101.

The main carriage 103 is supported on one side by means of a pair of flanged Wheels 111, 112 (see FIG. 1) journalled on lugs depending from the ends of the carriage and riding on a rail 113 supported by brackets -114 secured to legs 102 and extending from one side of the table structure. On the other side carriage 103 is supported on rollers 116 journalled on the lower ends of a-rms 121, said rollers riding on a at way 117 .mounted on brackets 118 projecting from the legs `102 on the related side of the structure. The

anged ywheels

111 and 112 serve both to support and guide the carriage 103 to maintain it in an accurate position longitudinally aligned with the table, while the rollers 116 on the other side serve merely to support the carriage. The upper end of each of the roller-supporting arms 121 has a bush 122 secured to it (see e.g. FIG. 2) which is slidable upon a bar 123 extending longitudinally along a side of the carriage 103` and secured tat 'both ends by way of lugs 125, 126. Pivotal adjustment of the bushes 122 around `the bar '123 is a means of accurately adjusting the elevation of carriage 1013 above the table, while sliding adjustment of the bushes along the bar permits of adapting a given carriage to tables of different size. Blocking means, such as set screws (not shown) are provided for blocking the hubs or bushes 122 in the desired angularly and axially adjusted positions.

Longitudinal displacement of the carriage 103 is produced by means of an electric motor 128 mounted near one end of said carriage and drivingly connected to the related anged wheel 111 by way of la gear reducer 129, a sprocket 131 having an incorporated friction clutch coupling, a sprocket chain 132 and a sprocket 133 coaxially secured to pulley 1111. Manual means such as 'a manual lever 134 are provided for releasing the aforesaid friction clutch. The automatic control means for carriage motor 128 will be later described.

Pattern frame carrier 104 mainly comprises a square frame made up from four

tube sections

136, 137, 138, 139 rigidly interconnected at their ends by corner members such as 141 (FIG. 4) which in turn are supported from the four corners of carriage 103 through supporting means permitting vertical up-and-down displacement of frame carrier 104 relative to the table. Each framefcarrier supporting means comprises (as shown particularly in FIG. 4) a drum-like cam 143 journalled for rotation about a vertical axis on the carriage 103 through ball thrust ibearings 145 and formed with a helical camway groove 144. Engaging the groove is a follower roller 146 journalled on a pin 147 which extends inwardly from the peripheral wall of a cylindrical casing i148 which surrounds the cam -143 so that cam 143 is freely rotatable in said casing. Casing 148 has its top irmly but removably secured -to the related corner member 141 of the frame carrier l104 by way of a screw provided with a knurled head 149 protruding above the corner member.

The proper relative angular position between the corner member 141 and cylindrical casing 148 is assured by a locator pin 152 spaced from screw v149. In the practical construction of the embodiment shown, the printing frame carrier is made mainly of aluminum alloy in the interests of light weight. The corner member 141 as part of said frame is made of aluminium. The casing 148 on the other hand is made of steel for greater rigidity. Accordingly, rather than providing the clamping and positioning connection directly between the two

parts

141 and 148 made of materials of different hardness, which would be mechanically unsatisfactory there is provided a cover plate 154 made of steel overlying the top of the corner member 141 and secured to it by screws 153. The plate 154 is formed with apertures through which the clamping screw 1149 and the locator pin 152 respectively extend.

Secured to the under side of cam 143 coaxially with it by means of flathead screws 157 is a sprocket 158. It will be understood `that an assembly such as just described and including the cam 143 is provided at each of the four corners of the frame carrier 104. Rotational movements are imparted to tall four cams in synchronism, at properly timed periods in the operating cycle, from an electric motor 159 mounted near one end of carriage 103 (see FIG. 2). The drive from motor 159 includes a speed reducer 161, a sprocket 162 on the reducer output shaft through a 4built-in friction clutch, a and sprocket chain 163 trained over intermediate sprockets 164, 165 and thence trained about all four sprockets similar to the aforementioned sprocket 158 coaxially secured to each of the four cams such as 143. It will be understood that the four cams y143` are rotated at a predetermined time in the cycle rst one way then the other, thereby imparting through the camway grooves 144 tand follower rollers 146 a vertical reciprocation to the frame carrier 104, as will later be described in detail.

Frame carrier 104 carries a printing frame 171 removably attached to it by way of

lugs

172, 173, i174 projecting from opposite sides of the frame and resting on parallel cross members 176, 177. The cross members in turn are supported on the

tube members

138, 139 of frame carrier .104 for longitudinal displacement with respect to them, and are blockable in any adjusted longitudinal position through means not shown. The frame 4171 may Ibe of any suitable conventional type, though it is preferably of the colour-storing type described in U.S. application led by me on November 27, 1961.

A squeegee carrier is movably supported on the frame carrier 104 on the one side by way of two sets of three rollers 181, `182, 183 (FIG. 3) adapted to ride the length of the tubular frame member 136, yand on the other side by way of a single pair of

rollers

184 and 185 engaging the top and bottom generatrices of the opposite tubular member 137 in the vertical midplane of said member. In each of the two sets of three

rollers

181, 182, 183, which sets are spaced longitudinally along the tube member 136, -there is provided an undermost roller 181 engaging the bottom generatrix of said tubular member and two

side rollers

182, 183 engaging side generatrices of the member as shown, so as to guide the corresponding end of the squeegee-carrier `105 along member l136.

For reciprocating the squeegee carrier 105 Iacross the frame carrier 104 during the operating cycle of the machine as later described, there is provided an electric motor 187 secured to frame-carrier 104 at one end of tube member 136 (see FIG. 2). The drive from motor 187 includes reducer gear 188, sprocket I189 on the re ducer output shaft, sprocket chain 191 trained over sprocket 189 land over another sprocket `192 journalled on the frame carrier 104 near the opposite end of tube 136. Chain 191 has one of its links secured to the squeegee car rier 105 as shown at 194. The means for controlling motor `187 as well as the other two motors mentioned above to ensure the desired timed movements of the squeegce carrier will be later described.

A squeegee 196 herein comprises a str-ip of rubber or the like (see FIGS. 3 and 5) gripped in a mount 197 universally connected for movement about two mutually normal horizontal shafts `198, 206, to the lower end of a vertical rod 199 which extends slidably through an opening formed in a support 201 -upstanding from the squeegee carrier 105. To limit the angular inclination of the squeegee and its mount relative to the vertical plane about the axis `198 there are provided two stop plates 202 projecting upwardly from the squeeqee mount 197 and adapted to abut alternately against the opposite walls of a slot 203 formed in the squeegee carrier `105.

In operation, a stencil `205 is mounted across the bottom of the printing `frame 171, and the squeegee 196 rests against the upper surface of the stencil by the action of gravity aided by the adjustable force of two tension springs 207 (FIG. 3) having their lower ends attached to the sides of the support 201 'and their upper ends attached to the corresponding ends of a member 208 having a central aperture freely surrounding a threaded shank 209 forming an upward extension of the rod 199. The member 208 is gripped between a pair of lock-nuts 211, 212 threaded on the shank 209 and having knurled cylindrical side surfaces, whereby rotation of the lower nut 211 :after disengagement of the lock-nut 212 will permit up-anddown adjustment of spring-anchoring member 208 yand hence the tension of springs 207 and the pressure with which the squeegee is applied on the stencil. A vertical scale provided on a strip 21d` upstanding from the support 231 cooperated with an index 213 projecting from rod 199 to indicate the adjusted heigh-t of the squeegee, while the same scale cooperating with an index 214 projecting from member 203 indicates the adjusted squeegee pressure, thereby facilitating the settingr up of predetermined working conditions on the machine on resuming operations after a shut down, change or work or the like.

An air damper device is associated with the squeegee to control its vertical motion and comprises an air cylinder 215 secured by a bracket to rod 199 and a piston 216 slidable therein and having a piston rod 217 secured to the -top of the support 261.

Means are provided for lifting the squeegee off the stencil at each end `of its horizontal reciprocation and comprise a `carnrning device including a pair of inclined ramps 221 (see FIGS. and 2) forming a two-tined fork secured by means of a horizontal hinge connection 223 to one end of :a tubular bar 224 supported above the frame carrier 104 by 'way of a bracket including :a xed sleeve member 225 in which the bar 224 is silidable a limited amount as presently described. The camming inclines or ramps 221 are adapted to be engaged by la pair of rollers 222 pivoted on a common horizontal axis 218 supported =by a collar 219 iadapted to be blocked at a selected adjusted height upon the squeegee-carrier rod 199. 'the fork-like camming member 221 is normally supported in the projecting position shown in FIG. 5, but can be retracted -by counterclockwise rotation yabou-t its hinge pin 223 in the direction indicated by the arrow f1 as will presently appear. At the opposite side of frame 171 there is a similar arrangement including camming fork 226 (FIG. 2) mounted on la bar 228.

As the squeegee-carrier nears the end of its stroke the roller-s 222 engage the upper surface of camming member 221 (or 224) and move up the incline, thereby lifting the squeegee assembly olf `the stencil. The rollers 222 after reaching the top of the incline drop down into `an :arcuate receiving or rest member 227 secured behind the incline as shown. When the squeegee carrier starts travelling in the opposite direction, at a later point of the operating cycle to be `described further on in detail, the rollers 222 engage the under side of the inclined 'cam member 221, as will be `apparent from FIG. 5, and thereby cause the member 221 .to rotate counterclockwise about the pivot 223 to allo-w the unimpeded downward movement of the rollers 222. The squeegee assembly is thus lowered down into contact with the surface of the stencil and assumes its normal inclination `as defined by abutment of plates 292 against one side wall of the slot 206 in squeegee-carrier 265.

A ilange 233 of lbar 2214 positioned within the sleeve like support 225 facts to compress a spring 232 between itself and an end 'w-all of the cylinder-like support 225 -to provide a damping action 4towards the end of the outward stroke of the squeegee carrier. Another -ilange 231 secured on bar 224 outside the cylinder member 225 serves as `a stop limi-ting the damping stroke by abutment against the related outer end surface of cylinder support 225. The

collars

231 and 233 are slidable along bar 224 and are blockab'le at 'adjusted positions thereon -by means of respect-

ive set screws

234 and 235 for `adjusting the longitudinal position of the camming device 221 relatively to the frame carrier 104.

It will be recalled that the three main relative displacements of the components so far described, i.e. displacements of carriage 163 along table 101, up-and-down motion of the fname carrier 104 on carriage 103, and traverse of squeegee carrier 1615, are respectively produced by and a secondary switchboard 239 (FIGS. l and 2) supported on :carriage 103. The manual switching controls and circuits yare shown in FIGS. 12a and 12b, and will now be enumerated together with their general functions; these functions wil-l be more clearly understood after a reading of the detailed description of operation that will follow.

The manual switch controls mounted on main switchboard 238 include the following:

There is provided a double-pole switch having the two pairs `oi? contacts respectively designated MAV-la and MAV-lb, closure of ywhich produces for-ward displacement of main carriage I163, There is another double-pole switch with the two pairs of contacts MAR-1a `and MAR- 1b closure of which produces rearward or return displacemen-t of main carriage 103. A switch H1 is actuable to stop the movement of the main carriage 103. A threepole switch including the three contact pairs Sa, Sb, Sc is called the `anrester switch and its function will appear later. A switch Rau is closable to cause forward displacement of the squeegee. A switch Rar is closable to cause rear- -ward or return movement of the squeegee. All of the switches so far mentioned are of the push-button type, as schematically shown.

There is further provided on main switchboard 238 a selector switch device not shown but represented by its eight contact pairs a, b, c, d, e, f, g, h which, as will later appear, can be manually placed in any one of three configurations to provide three different modes of squeegee operation, viz. Manual sweep, Single-sweep, and Double-sweep. In the following table the letter O indicates an open and l a closed con-tact pair:

Selector Contacts:

position Operation a b c d e f g h No. .1 Manual sweep 0 1 1 O O O O O No. 2 Single sweep l O O l O 1 O 1 No. 3 Double sweep 1 `O O O `1 Ol 1 O The signicance of the three modes of squeegee-sweep and the manner in which the selector contacts operate to provide them will appear later. j

The main switchboard 238 further includes a general three-pole control switch P shown in HG. lil, closure of which supplies power from a three-phase fnetwork to the three motors 1.28, 159 and 187 as will be later described in greater detail. Finally the main -switchboard 238 carries a control lamp L1 (FIG. 11) illumination of which indicates that the machine circuits are energized, and a signal lamp L2 which lights up when the main carriage 103 is travelling on its high-speed return stroke.

The secondary switchboard 239 is positioned at the other side orf the table from main switchboard 238, and only supports three repeater switches to enable commanding the main machine functions from either side of the machine for convenience. Specifically swicthboard 239 includes a double-pole repeater swi-tch MAV-Za, MAV-Zb, for commanding forward displacement of the main carriage 103, =and a double-pole repeater switch MAR-2a, MAR-2b for commanding quick return displacement of the main carriage. It also carries a repeater halt switch H2 for arresting movement of the main carriage.

The automatic controls and circuits will now be described. There -are provided a number of contactors and relays mounted on the main switchboard. The contactors are six in number, Vone pair for each of the three

motors

128, 159 and 187 (see FIG. 1l). In each pair, one contactor when energized completes a circuit for rotating the related motor in one sense, and the other in the other sense. Specifically:

Contactor AV when energized imparts (slow) forward rotation to carriage motor 128, and

Contacter AR when energized imparts (quick) reverse rotation to carriage motor 128.

Contactor D when energized imparts forward rotation to frame carrier motor 159 for downward frarne motion, and

Contactor M when energized imparts reverse rotation to motor 159 for upward frame motion.

Contacter A when energized imparts forward rotation to squeegee carrier motor 187, and

Contacter R when energized imparts reverse rotation to squeegee carrier motor 187.

The switchboard 238 also mounts six relays R1 through R6 which serve intermediate control :functions that will later appear. Certain of the contactors in addition to their motor controlling function also operate auxiliary contacts. These are designated by lower-case letters corresponding to the letters designating the contactors followed by a numeral. Thus arl and ar2 designate two auxiliary switches operated by contactor AR. Somewhat similarly r3a, r3b, r`3c designate three switches operated by relay R3.

Energization and deenergization of the contactors and relays during automatic operation of the machine is generally elected by limit micro-switches carried by the moving components, and designated by Roman numerals followed by lower-case letters.

For controlling the intermittent advance of carriage 103 there is provided on said carriage, for cooperation with carriage stops 255, an electromagnetic arrester device of special construction which will now be described. The device, generally designated 241 (see FIGS. l, 8, 9 and 10) comprises a base-plate 242 secured to a side of main carriage 103 and supporting a solenoid E in the axial recess of which an armature is movable, which extends from .a lever 244 pivoted at 245 to plate 242. On energization of solenoid E, lever 244 is pivotcd clockwise (cf. drawing) against the force of a tension spring 246. On deenergization of the solenoid E, spring 246 restores the lever 244 to a lowered rest position in abutment with a stop 247 on plate 242. Pivoted to lever 244 a-t 251 is the upper end of an arrester arm 249 the lower part of which can swing between a pair of

stops

252, 253 on baseplate 242. Arrester arm 249 is movable to a raised or retracted position (FIG. 8) when lever 244 is rocked counterclockwise on energization of solenoid E, and to a downwardly projected position (FIGS. 9 and 10) when lever 244 is restored on deenergization of solenoid E. A spring 254 urges arm 249 into engagement with stop 253. The lower end of arrester arm 249 is adapted when in the projected position to be engaged by a series of adjustable carriage stops 255 supported in preset positions along a straight bar 256 secured to the brackets 114 and extending parallel to the guide rail r113` supporting the main carriage 103. Also secured to base plate 242 is an air damper cylinder 258 containing a piston connected by a rod 259 to an intermediate point of arrester arm 249. The positions of stops 255 along the bar 256 are preset in accordance with the successive positions to which the carriage is required to be advanced or stepped during the printing cycle for printing successive patterns on the work.

The arrester arm 249 when swung to the FIG. 9 position by engagement with a stop 255 actuates a microswitch III mounted on base plate 241 by way of a slot in said base plate providing a limited degree of adjustment of the position of microswitch III in the direction of carriage movement. Also mounted on baseplate 241 is another microswitch VIII adapted for actuation by the stops 255 and also adjustable in a slot of the baseplate.

The control circuit for motor 12S displacing the main carriage 103 `further includes two opposite limit switches I and II (see FIG. 2) supported from

brackets

271 and 272 projecting from the opposite ends of main carriage 103. The switches are actuated by convex cam surfaces 273 and 274 respectively secured to the inner faces of end stops adjustably positioned along the bar 256 at positions corresponding to the respective ends of the piece of fabric or other work to be printed, bonded to the surface of the table.

The motor 159 imparting vertical displacements to the frame carrier 104 is operated through means including a linger 266 projecting from a link of the sprocket chain 163 and adapted to actuate in succession a pair of limit switches IV and VII mounted on main carriage 103.

The third motor 187 imparting movement to the squeegee carrier 10S includes among its control instrumentalities a pair of switches V and VI respectively secured to the bars 224 and 228 which as earlier described support the squeegee raising cams 221 and 226. Switches V and VI are respectively actuated by

cams

267 and 268 projecting in opposite directions from the squeegee support 201 mounted on carrier 105.

Electric power is supplied to the main control switch P on the switchboard 238 through any suitable arrangement, not shown, including insulated conductor rails secured to the table 101 and cooperating with trolleys or friction contacts on the main carriage. From the main switch the electric energy is distributed to the various electric control means described through the feed circuits shown in FIGS. ll, 12a, 12b.

Before proceeding with the detailed description of an operating cycle of the machine, such operation will first be summarized in a broad way. In this summary description the various timed movements of the motors will be stated without indicating how they are actually brought about.

A piece of fabric 109 to be printed is tixedly secure, e.g. adhesively bonded, to the surface of table 101, and a stencil 205 of the desired pattern is positioned in the frame 171. The main'carriage 103, which supports the trame carrier 104 carrying pattern frame 171, is positioned at its initial position on the machine table 101, i.e. the left hand end of the table as seen in FIGS. 1 and 2. Motor 159 now causes downward movement of frame carrier 104 to apply the stencil 20S against the work 109. When the frame carrier has reached the lowermost point of its displacement motor 137 is started and traverses squeegee-carrier 105 across the frame. During this traverse the squeegee 196 sweeps across the stencil lengthwise of the table and on reaching the far end of the stencil, the squeegee is lifted olf the stencil surface by the action of cam 226. At this time the motor 159 imparts an upward movement to the frame carrier 104. Then the arrester arm 249 is rocked out of engagement with a carriage stop 255 so that motor 12S which is running continuously now causes, through the friction clutch associated with gear 131, a rightward displacement of the main carriage 103. As carriage 103 moves rightward (FIGS. l and 2) it moves past the first carriage stop 25S it encounters without being stopped by it, for reasons later indicated, and is only arrested in its advance by the next stop 255, through action of this stop on arrester arm 249 which is pressed into engagement with said stop by the action of the torque of motor 128 through the friction clutch associated with gear 131, which at this time slips without stalling the motor. Thus the carriage 103 is positively and accurately blocked at each of its prescribed positions along the table, by the action of the motor torque.

Abutment of the arrester arm 249 against the carriage stop again causes a downward movement of the frame carrier 104 and the termination of this downward movement in turn initiates traverse of the squeegee carrier 4105 in a direction reverse from that of the preceding traverse or sweep of the squeegee, assuming the singlesweep mode of operation was selected as later described.

In this way the main carriage is automatically displaced from one end to the other end of the work to be printed without any manual intervention on the part of the operator, and the printing operations are performed with maximum etliciency and speed since each operating step is initiated at termination of the preceeding step. After the main carriage has reached the end of its prescribed advance, the carriage motor 128 is energized in reverse at high speed to return the carriage at a rapid rate to its initial position.

It is noted that the use of a printing frame 10 of the ink-storing type previously mentioned is especially desirable since it avoids the necessity of having to replenish the store of printing liquid during the advance of the carriage 103 across the table. Preferably moreover the frame carrier 104 is square as shown, and can be mounted in either of two mutually perpendicular positions on the main carriage 103, making it possible to use stencils of either type designed for sweeping warpwise and weftwise across the fabric.

An operating cycle of the machine will now be described in detail. It is assumed iirst it is desired to work in the single-sweep Inode, i.e. the squeegee will sweep once across the stencil in one direction at one dwell period of main carriage 103, and will sweep across the stencil in the opposite direction at the next dwell period. At the initial point of the cycle the frame carrier 104 is assumed to be in uppermost position and squeegee carrier 10S at the control station end of the table, i.e. the right end in FIG. 2. Since the machine is set for single-sweep work, the selector contacts are in their No. 2 conditions indicated earlier, wherein switches a, d, f, h, are closed and switches b, c, e, g are open (see FIGS. 12a and 12b). Moreover arrester arm 249 is in the lowermost position shown in FIG. l0. To start the machine in operation, the main power switch P is closed and illumination of control lamp L1 is noted. Either of the two forwarddisplacement push-button switches MAV-l or MAV-Z, say switch MAV-1 on the main switchboard, is depressed, whereupon contacts MAV-a are closed and contacts MAV-lb opened. Closure of MAV-la energizes contactor winding AV, thereby closing its hold contacts av, to provide a hold circuit for contactor AV through the circuit 1-3-4-5-6-7-8-2. Referring to FIG. 11, it will be noted that energization of contactor AV closes three switches to energize the main carriage motor 128 in a sense causing rotation of the motor to advance the main carriage 103 rightward in FIGS. 1 and 2. At the same time closure of MAV-la has energized relay winding R4, closing relay contacts r4!) and r4c through the circuit 1-38-45-39-40-41-43-2 (FIG. 12b) to energize solenoid E in arrester device 241. This rocks lever 244 to the position shown in FIG. 8, retracting arrester arm 249 to disengage it from the stop 255 with which it was engaged. The main carriage 103 is now able to advance through the action of friction clutch 131 which up to this point was slipping.

It will be noted that closure of relay switch r4a (FIG. 12a) on energization of relay R4 serves to prepare the circuits for energizing the contactors A and R controlling the forward and return displacements of the squeegee.

n the switch VIII of arrester unit 241 encountering the foremost one of the carriage stops 255 it closes its contacts (FIG. 12b), energizing relay winding R3, which closes hold contacts R311 completing a hold circuit for R3 through 1-38-45-3942-2 Normally closed relay contacts rSc (FIG. 12a) are now opened, deenergizing relay R1. Energization of R3 also opens the normally closed contacts r3b, (FIG. 12b) which breaks the energizing circuit for solenoid E. Arrester arm 249 is therefore restored to its normal projected position after having moved past the initial carriage stop 255. It is noted in this connection that the position of switch VIII on plate 242 was so preset that whenever the arm 249 is moved to its projected position due to deenergization of solenoid E consequent on actuation of switch VIII by a carriage stop 255, said arm has already moved beyond the particular stop 255 that was responsible for actuation of the switch. Arrester arm 249 now being in its lowered or projected position will engage the next, or second carriage stop 255 (FIG. 10) and thereby arrest the movement of the main carriage 103, with the impact being damped by the action of damper 258. (FIG. 9). Motor 12S continues rotating but the friction clutch associated with pulley 131 slips while maintaining the arrester arm 249 in engagement with the carriage stop. The carriage and the entire movable assembly of the machine is thus retained in an accurate predetermined position as determined only by the preset position of the proper stop 255 along bar 256, as required for correct register of the stencil with the work.

It will thus be seen that the main carriage skips one out of every two printing positions, thereby providing adequate time for the drying of each successive print, as required in the frame-printing technique to which the invention relates, wherein it is undesirable to print the second of two juxtaposed frames before the rst of the frames is completely dry. Thereafter a second printing run is effected to print the intervening frames which were skipped in the first run just considered. It should be observed however that the machine of the invention also permits, when desired, other modes of operation wherein all adjacent frame positions may be printed in succession, or alternatively one out of three frames may be printed so as to complete the full printing process in three runs. These alternative procedures will be later described.

The arrester arm 249 toward the end of its rocking movement actuates switch III to closed position (see FIG. 12a) thereby completing an energizing circuit through now-closed switches IVa and rla for contactor Winding D which controls the downward movement of the frame carrier 105. The said energizing circuit is traceable through 1-13-14-15-2. FIG. 11 shows that energization of contactor winding D closes a three-phase switch which energizes motor 159, which is now rotated in the sense causing downward movement of frame carrier 105. At the same time auxiliary contacts d of contactor D are closed to provide through 1-18-19-44-2 an energizing circuit for relay R5. Contacts rSa are now closed to hold relay R5. Contacts rSb are opened, thereby preventing unwanted energization of contactor M causing upward movement of the frame carrier as presently described, the energizing circuit for said contactor being cut olf at 21-22.

The position of switch III on arrestor baseplate 242 (FIG. 9) may be preadjusted to ensure that the downward movement of the frame carrier will commence a short time before the main carriage 103 has completely stopped, thereby effecting a saving in operating time.

On the frame carrier 105 starting its downward movement the switch VII (FIG. 2) is released, permitting closure of contacts VIIa and VIIb at the points 20-21 and 18--34 respectively of the circuits shown. When the frame carrier 10S reaches its lowermost position, i.e. the printing position, the finger 266 (FIG. 2) projecting from the sprocket chain 236 actuates switch IV, whereupon switch contacts IVa are opened (at 13-14) and contacts IVb are closed (at 2324). Opening of IVa deenergizes contactor D and arrests the operation of motor 159 moving the frame-carrier. Closure of IVb energizes contactor A by way of the circuit 1-18-23-2425262. As shown in FIG. l1, energization of contactor winding A closes three-pole contacts to supply power to squeegee motor 187 in the sense causing forward sweep of the squeegee, i.e. rightward in FIG. 1.

Energization of contactor A also closes auxiliary contacts a thereby completing a circuit at 3-36 for energizing relay winding R6 Whose hold contacts r6b are thereupon closed. Energization of relay R6 opens the contacts r6a, breaking the circuit at points lid- 31, to prevent any accidental energization of the contactor R commanding the return sweep of the squeegee. Energization of relay R6 also opens contacts r6c, cutting off the energizing circuit for relay R3 whose contacts r3a are thereupon opened at 39-42, whose contacts r3b are closed at 40-41, and whose contacts r3c are closed at points 1-16. The energizing circuit for arrestor solenoid E is therefore maintained in cut-off condition, preventing unwanted displacement of the carriage 103 over the rails.

The squeegee carrier llS is now traversed by motor 187 leftward (FIGS. 1 and 2). At the start of this traverse switch VI is released, opening contacts VIa to break the energizing circuit for relay R5 at points 18-19. Deenergization of R5 closes the contacts rSb and prepares the subsequent energization of contactor M responsible for the upward displacement of the frame carrier. Contacts VIb are closed and prepare a circuit for the subsequent energization of contactor R commanding the return sweep of the squeegee. The forward or outward sweep of the squeegee is limited by limit switch V being actuated by ramp 267 (FIGS. 1, 2 and 5) thereby opening contacts Va at 24-25 to deenergize contactor A. At the same time contacts Vb are closed to complete an energizing circuit 1-18-23-28-19-21'9-21-22-2 for the contactor winding M commanding upward movement of the frame-carrier. Energization of M is seen from FIG. 11 to energize frame-carrier motor 159 in the reverse sense from the previous one, i.e. in a sense to raise the frame carrier 105.

On energization of contactor winding M, an auxiliary pair of contacts m thereof is closed, completing at the points 16-17 an energizing circuit for relay R1. Hold contacts rlb are closed to hold relay R1 energized, and contacts rla are opened to prevent unwanted energization of contactor D commanding the downward movement of the frame-carrier on release of switch IV closing contacts IVa at 13-14. The upward movement of the frame carrier 105 is limited by switch VII being actuated by linger 266. This opens contacts VIIa and breaks the energizing circuit for contactor M at points Ztl-21. At the same time opening of contacts VIIb breaks the energizing circuit for R6 at 18-34. Contacts r6c are thereupon closed, causing energization of arrestor solenoid E, raising the arrestor arm 249.

The `arm 249 on being raised allows the main carriage 103 to proceed on its forward movement, to accomplish a further displacement equal to twice the elementary spacing between consecutive carriage stops 255 as earlier described.

The termination of the main carriage displacement and the subsequent lowering of the frame carrier 105 will then occur again in a manner similar to that described above in connection with'the rst step of displacement, except that in this case the switch V is in its operative condition in which the circuit is open at points 24-25 and closed at points 23-28, and switch VI is in idle position in which the circuit is open at 18-19 and closed at 29-30.

Closure of the limit switch IV at points 23-24 completes an energizing circuit through 1-18-23-24-29- 30-31-2 for the contactor winding R commanding return movement of the squeegee. Energization of R closes the motor contacts to energize squeegee motor 41'1'37in the direction for rightward squeegee displacement (FIGS. 1 and 2). At the same time closure of contacts r at points 34-37 energizes relay R2, closing hold contacts r2b therefor. Contacts rZa are opened, preventing energization of contactor A commanding forward squeegee sweep at the time switch V is released after initiation of the return sweep of the squeegee closing contacts Va at 24-25. The opening of contacts Vb at 23-28 deenergizes the relay R5, whose contacts rSb are opened at 21-22. Energization of R2 causes opening of contacts r2d at 39--45, thereby deenergizing relay R3, whose contacts r3a are 1.?. opened at 39-42 while contacts r3b are closed at 40-41. The energizing circuit for solenoid E remains open. Moreover, the closure of contacts r2c at points `18---32 has no consequence since the contacts g at 28-32 are open.

The return sweep movement of the squeegee is limited by the limit switch VI which, on being actuated, cuts oft the energizing circuit for the contactor R commanding the return sweep of the squeegee by opening contacts VIb at 29--30. Closure of contacts Vla at 18--19 energizes the contactor M commanding upward movement of the frame carrier.

The cycle then proceeds as previously described, except that the frame carrier limit switch VII causes deenergization of relay R2 rather than R6, by the opening of contacts VIII: at '18-34. Deenergization of relay R2 closes contacts r2a which completes the energizing circuit for contactor A at 25-26, closes contacts r2b at 1'8--32 and closes contacts r2d at 45-39 and consequently energizes solenoid E to move arm 249 to retracted position, allowing the main carriage to proceed on its forward course.

The stepping cycle proceeds in a similar manner as many times as are necessary until the main carriage 163 has reached the end of its travel along the work. At this time switch I is actuated by the end stop 273 (FIG. 2). Contacts Ia of switch I open to break the energizing circuit for the contactor AV commanding forward carriage displacement at 4 5, and break the energizing circuit for relay R4. On the other hand contacts lb close to complete the energizing circuit for contactor AR commanding rapid return of the carriage, at points 4-9. Carriage motor 128 is now energized at high speed in the reverse direction. Contactor AR is held in energized condition by hold contacts arl. Energization of contactor AR in addition to energizing the motor 128 as just indicated closes auxiliary contacts ar?. at 1-41, thereby energizing solenoid E and hence retracting arrestor arm 249 for the duration of the carriage return movement. This rapid return movement is performed in a single stroke and is arrested on the carriage reaching its initial position by switch -II engaging the opposite end stop 274 (FIG. 2), thereby deenergizing the circuit for contactor AR at 4-10.

The operator may now, if necessary, replenish the store of printing liquid in the frame, and a new run can be initiated to print the intermediate frames that were skipped during the irst run just described, according to the earlier indicated procedure. -In this second run, it is therefore necessary to start the printing operations one step further than in the first run, and for this purpose the main carriage 103 may be advanced manually one step to bring it to its new initial position. This is done by actuating lever `134 (FIG. 2) disengaging the friction clutch 131 interposed in the main carriage drive path. This action simultaneously closes switch IX at points 33-411 to energize solenoid E and retract arrester arm 249 to release the carriage for advance. Moreover, the selector switch is set to the position indicated as No. 1 in the table earlier given, in which only selector contacts b and c are closed. On the other hand, the so-called arrester switch S on the main switchboard, may be actuated to shift its contacts Sa, Sb and Sc, thereby deenergizing solenoid E through contacts Sb and simultaneously preventing unwanted upward movement of the carrier frame during the operation of the energized selector switch.

It may be desired at any time during a printing process to perform any suitable number of squeegee sweeps, e.g. before the start of the printing process. For this purpose the switch button Rua or Rar may be depressed to close the contacts at 2724 or 33-29 respectively, and thereby energize the contactors A and R respectively commanding the forward and return movement of the squeegee carrier motor 189, without energizing the hold contacts of the respective contactors. ln such case the sweep strokes will still be limited in the forward and the return directions by the limit switches V and VI respectively.

Por manual sweeping, the selector switch is placed in position No. l, wherein only contacts b and c are closed. In this coniiguration of the circuit, depression of manual squeegee switch Rau wiil establish the circuit path 1-27- 24-25-26-2 to energize contactor A and cause a forward sweep of the squeegee, whereas depression of manual squeegee switch 'Rar will establish path 1-33-293t)-31-2 to energize contactor =R and cause a rearward sweep of the squeegee.

The provision of the various manual controls described is especially valuable for facilitating preliminary tests and adjustments of the machine, including adjustments relating to the colour pattern distribution on the printing frame and the presetting of the various stops to achieve the desired register of the frames.

In the various types of operation so far described the squeegee was actuated alternately in one direction and in the other. In contrast to this single-sweep operating mode, the machine includes provision for a double-sweep mode in which the squeegee is made to perform a twoway displacement at each printing step. To select the double-sweep operating mode the selector switch is set to position No. 3 previously detined, in which only the selector contacts a, e and g are closed. In this configuration, the initial portion of the operating cycle is unchanged up to the point at which the frame carrier y164 has been lowered to printing position and has thereby actuated limit switch IV. The description will now be taken up from this point on.

On actuation of limit switch IV, contactor AV and relay R4 are both energized. Contacts ra (1S-23), ric (1-38) and rlb (S9-49) are all closed. Relay R3 is energized, so that contacts r3a (E9- 42) Vare closed, while contacts r3b (4G-41) and rSc (1 -16) are open. Relay R5 is energized so that contacts rSa' (1Q-44) `and rSb (Z1- 22) lare open. Limit switch III is in operating position so that the circuit is closed between

points

1 and 13, while Alimit switch V is in idle position so that contacts Va (2@25) are closed while contacts Vb (Z3-281) are lopen. Limit switch VI is in operative position so that contacts VIa (1S-19) are closed and contacts Vlb (Z9-30) are open. Limit switch VII has just been released so that contacts VIla (2d-21) and VIIb (1S-34) are closed. Limit switch VIII has been depressed and then restored to idle position (contacts 39-42 open).

The opening of contacts IVa (1.3--14) deenergizes contactor M to arrest the downward movement of fname carrier 164-' and the closure of IVb (2S-24) energizes contactor A to cause forward displacement of the squeegee carrier 105. At the start of the forward displacement of squeegee carrier 105 limit switch VI is released, so that contacts Vla (18-19) are opened, and relay RS is deenengized so that contacts rSb are closed. Contacts VIb (Z9-30) are also closed. It is noted that -while the energization of contactor A has resulted in closure of contacts a (3S-36), this does not in the double-sweep mode establish an energizing circuit for relay R6 because of the open condition of selector contacts h (S4-35) hence relay R6 remains idle in this double-sweep mode of operation.

As the squeegee carrier 105 reaches the end of its -forwand (leftward) sweep, it again arcuates limit switch V (as in the single-sweep mode), opening contacts Va (2425) `and closing contacts Vb (Z3-28). Opening of Va (Z4- 25) deenengizes contactor A, :arresting forward rotation of squeegee motor 187, while closure of Vb (Z3-28) now energizes contactor R over the path 1-18-23-28`293t)312, since in the present configuration selector contacts e (2S-29) which were open in the single-sweep mode, are closed. Energization of contactor R starts up the squeegee motor 187 in reverse drive, causing squeegee carrier 105 to perform its backward sweep.

Energization of cont-actor R also closes contacts r (S4-37) to energize relay R2, such energizing being continued by closure of hold contacts rZb. Contacts rZc (1S-32) are thereby closed. This establishes an alternative circuit path for continued energization of contactor R (over 148-32-28-1940-31-2) after contacts `Vb (2S-28) are opened due to release of limit switch V shortly after the start of the return sweep. It is noted that the opening of contacts 12a (2S-26) prevents unwanted energization of contactor A commanding the forward squeegee sweep on re-closure of limit switch contacts Va. The opening of contacts r2d (45-39) serves to deenergize relay R3 while simultaneously maintaining solenoid E deenergized.

The return sweep of the squeegee carrier is again arrested by the action of limit switch VI which opens its contacts VIb (Z9-30). Closure of contacts VIa (l-19) of limit switch VI energizes contactor M to operate -motor 159 in the sense to lift the frame carrier 104.

The icycle then proceeds in the same manner as the single-sweep cycle previously described after completion of the squeegee sweep.

As so far described, the machine was preset to print one out of every two frame spaces, i.e. the main carriage 163 w-as made to skip every other stop 256 during its forward movement. However, in cases where the patterns are to be printed in non-:adjacent areas of the piece of fabric, this type of operation is unnecessary and the main carriage may be made to halt at each carriage stop and lower the sten-cil frame carrier 104 on to the work lat each stop. To obtain this type of operation, the micro-switch VIII of arrester device 241 (FIGS. l and 8) is moved to its foreino-st adjusted position on plate 242, in the direction of forward carriage displacement. When thus preset, the engagement of micro-switch VIII with the first carriage stop encountered by it after the carriage 103 has started, or resumed, its advance, causes deenergization of solenoid E to occur early enough to cause arrester arm 249' to engage said stop and thereby arrest :carriage advance, rather than movin-g in retracted position past sai-d stop and to engage only the next stop as -in the first type of operation. Thus the carriage 103, with microswitch VIII rthus preadjusted, will be arrested yat each successive stop 255 rather than at every other stop. Otherwise the operation is unchanged.

FIGS. 6 and 7 illustrate a modified arrangement for lifting the Iframe carrier 104 over the main carriage 103. Whereas in the first embodiment described the frame carrier was raised by a vertical translational movement through the simultaneous action of the helical cams positioned at all four corners of the frame carrier, in this modification the frame 4carrier 104 is swung upward about a horizontal axis extending `along one of its four sides. One advantage of this arrangement is that the stencil separates progressively from the fabric, rather than instantly over its whole surface; this advantage is of especial interest in the case of large-area stencils. In the construction shown the frame carrier 104 is rocked about an ideal horizontal axis provided by two aligned

pivots

231, 282

mounted at the upper ends of two pillars 2S3, 284 respectively upstanding from the main carriage `193 at two adjacent corners of `frame carrier 11M. At the remaining two corners helical cam devices are provided generally similar to those earlier described, each including a cylinder cam with `a helical camway groove 143 rotatable in a cylindrical casing 148' from which a follower roller projects into the camway groove to cause vertical reciprocation of said casing 14S on rotation of the cam. In this case however each casing 148 is connected with the related end member 236 of the frame carrier by way of a clevis upstandinvg from the top of casing 148i and extending through an elongated slot formed in the member 286, so as to permit relative tilting of the frame members such aS 136 as shown at the upper part of FIG. 6. A retainer pin 287 extends through slots 28g formed in the clevis. It will be understood that in this embodiment raising ofthe frame carrier 1M requires actuation of only ltwo cams not four. The cams 143 each have

sprocket wheels

291 or 292 secured coaxially to its base and interconnected by an endless chain 289 (FIG. 7). One of the cams has a further sprocket 293 coaxial with it and connected by another endless chain 294 with a sprocket 295 mounted on the output shaft of a reducer gear 296 driven from an electric motor 297 which corresponds in function to motor 159 of the rst embodiment and is controlled in a similar manner.

FIG. 6 further illustrates how the tubular side members of the frame carrier 104 are desirably mounted in a dismountable manner so as to permit pivotal adjustment of the two

tubes

136 and 137 over which the roller supporting the squeegee carrier 105 rides. As shown, the connection between tube 136 and the end bracket 286 comprises a threaded rod 299 extending coaxially into the tube from the end of it and having a nut 391 mounted on it, the nut having a frustoconical outer surface engaged in the complementary frustoconical inner surface of a slotted bush 302, so that by screwing the threaded shank 299 into the nut the bush is expanded to provide a firm connection. The advantage of this construction is that after a certain period of service when certain generatrices of the

tubes

136 and 137 have been subjected to substantial wear from the rolling friction of the rollers such as 181, 182, 133, and 184, 185 (see FIG. 3) thereagainst, the tubes can easily be loosened and turned by a suitable angle to expose intact generatrices to the rollers. Preferably

tubes

136 and 137 have a hardened, e.g. chrome-plated, surface. It will be understood that the dismountable frame construction just described with reference to FIG. 6 and 7 can advantageously be used in the case of the iirst embodiment described.

FIG. 13 illustrates a partial modification of the control circuit of FIGS. 12a-b, lthe circuit of FIG. 13 being adapted to replace the portion of FIG. 12b located to the right of the chain line XIII-XIII.

The modification involves the means used for skipping a predetermined number of stops during the advance of the main carriage 163, and is of especial use in the printing of large pattern areas, and/or where it is desired to skip more than one, e.g. two, frames at each step of the carriage. Basically this modification uses a time delay device, c g. a time-r, Mn for delaying the energization of the solenoid E controlling the retraction of arrester arm 249.

As shown, a timer unit Mn has supply terminals connected across the supply conductors at 1 and 2. On energization of the relay R4 as earlier described, a voltage appears across the terminals 39 and 46 of the timer for a prescribed period determined by the setting of the timer. Thus the solenoid E remains energized and .the arrester varm 249 remains in its raised or retracted position for a corresponding period, which is made Ato correspond with the time required by the carriage 193 to move past a desired number of carriage stops 256 Without being stopped thereby. After the time has lapsed a voltage appears at terminal 42 of the timer and is applied to energize the relay R3, whereupon contacts r3c are opened to deenergize solenoid E. The arrester arm 249 is lowered to projected position and will arrest the carriage 103 on encountering the next stop 255. The timing device Min may assume any suitable form, eg. electronic, or that of a delay device.

It will be apparent from the foregoing description of the improved frame printing machine that an extremely advantageous form of automatically operating machine has been provided, in which a complete cyclic operating sequence is obtained having desired characteristics accurately predeterminable by simply presetting the stops 255 at the desired locations along the rail 256, a convenional operation normally required in present-day manual frame printing machines. The fully automatic operation greatly increases production speed for several reasons. First, there are no idle periods between successive printing steps in a given 16 cycle, and between successive cycles, since each step or each cycle is initiated on termination of Ithe preceding step or the preceding cycle. Moreover, manual operation of the squeegee is rather diicult and tiring and generally requires more than one sweeps per print if the printing is to be successful. Vvith the automatic machine on other hand, the squeegee is applied against the work under a positive pressure considerably higher than that exertable by muscular force, so that equivalent or better printing can be obtained with a single sweep (or perhaps two) of the squeegee, thereby achieving a further saving in time while improving the quality of the work.

Production is further increased because it is unnecessary to supply printing liquid to the frame during the cycle. This also reduces the number of operators required. A single operator will be able to operate several automatic printing units of the type described herein.

It will also be apparent from the foregoing that much more uniform results are obtainable when all of the operations are performed automatically as here described, and hence under strictly comparable conditions as is the case herein, especially as regards uniformity of squeegee pressure, tilt angle and number of sweeps and without replenishment of the store of ink dur-ing the pass.

The feature that no step of the cycle is allowed to commence before the one preceding it has been completed, imparts a high degree of reliability to the printing operations.

It will be understood that many modifications, in addition to those mentioned, may be conceived by those familiar with the art without exceeding the scope of the present invention. According to one modification specilically contemplated, automatic mechanism and control equipment operating on similar lines to that described and illustrated may be installed on existing manual frame printing machines, possibly using the existing printing frames and stencils.

What is claimed is:

l. A frame printing machine which comprises an elongated table adapted to receive a sheet of material to be printed on, a main carriage supported for longitudinal displacement over the table, a frame carrier having a printing pattern frame and supported on said carriage for movement between a printing position in engagement with said material on the table and a raised position, a squeegee assembly supported for horizontal traversing displacement across said frame carrier when in printing position to apply a printing substance through said pattern to said material, and control means for automatically impar-ting to said carriage, frame carrier and squeegee assembly a cyclic sequence of displacements including: advancing the carriage in steps to a series of pre-set positions spaced along the table; at each step moving the frame carrier to printing position, traversing the squeegee assembly across the frame carrier, and moving .the frame carrier back to raised position; and returning the carriage to an initial position on the table after a last step of advance.

2. A frame printing machine which comprises an elongated table adapted to receive a sheet of material to be printed on; a main carriage supported for longitudinal displacement over the table; a frame carrier having a printing pattern frame and supported on said carriage for movement between a printing position in engagement with said material and a raised position; a squeegee assembly supported for horizontal traversing displacement across said frame carrier when in printing position to apply a printing substance through the pattern to said material; electric motor means for displacing the carriage, frame carrier and squeegee assembly respectively; and control means including electric relay and switching means for operating said motor means automatically to produce a cyclic sequence of displacements comprising: advancing the carriage in steps to a series of preset positions spaced along the table; at each step moving the frame carrier to printing position, traversing the squeegee assembly across the frame carrier and moving the frame carrier back to raised position; and returning the carriage to an initial position on the table after a last step of advance; including switching means actuated on substantial completion of one step in the cyclic sequence to initiate the following step of the sequence.

3. The machine claimed in claim 2, including selector means presettable to a first position for selecting a first mode of operation in which the squeegee assembly performs a one-way traverse at each step of the carriage and a second mode of operation in which the squeegee assembly performs a two-way traverse at each step of the carriage.

4. The machine claimed in claim 2, wherein said frame carrier is generally rectangular, and including at least one pair of helical cam units mounted on the carriage for rotation about vertical axes adjacent respective corners of said frame carrier and follower means projecting from said frame carrier to cooperate with said helical cam units fto move the frame carrier between its printing and raised positions on rotation of the cam units, and drive means for simultaneously rotating said cam units from said electric motor means under control of said switching means.

5. The machine claimed in claim 2, wherein said frame carrier is movable in parallel displacement between its said positions.

6. The machine claimed in claim 2, wherein said frame carrier is movable between its said positions in rotation about a substantially horizontal axis lying on the plane of said table.

7. The machine claimed in claim 2, including a solenoid operable to one electrical condition to retract the arrester arm and operable to another electrical condition to project the arm, and a switch engageable by a carriage stop to operate the solenoid to its said other condition.

8. The machine claimed in claim 7, including a further switch actuated by the frame carrier substantially on attaining its raised position for operating said solenoid to said one condition thereof.

9. A frame printing machine which comprises an elongated table adapted to receive a sheet of material to be printed on; a main carriage supported for longitudinal displacement over the table; a frame carrier having a printing pattern frame and supported on said carriage for movement between a printing position in engagement with said material and a raised position; a squeegee assembly supported for horizontal traversing displacement across said frame carrier when in printing position to apply a printing substance through the pattern to said material; a continuously running motor; drive means connecting said motor for displacing said lcarriage and including a slip coupling; a bar extending alongside the table and a plurality of carriage stops adjustable to spaced positions therealong to preset a plurality of printing positions for said carriage along the length of said work; an arrester arm on said carriage movable between a projected position in which said arm is engageable with said carriage stops and a retracted position; said slip coupling adapted to slip during engagement of said arm with a carriage stop to allow the carriage to remain stationary without stalling said motor; further motor means for displacing the frame carrier and squeegee assembly respectively; means responsive to engagement of the arrester arm with a carriage stop for operating said further motor means to move the frame carrier to printing position, traverse the squeegee assembly and move the frame 'carrier to raised position; and means responsive to movement of the frame carrier to raised position for temporarily moving said arrester arm to retracted position t permit advance of the carriage by said continuously running motor to a further printing position.

10. The machine claimed in claim 9, including sensing 18 means mounted on said carriage behind of said arrester arm in the direction of carriage advance and sensing movement of a carriage stop therepast and means responsive to said sensing means for moving the arrester arm to projected position.

ll. The machine claimed in claim 9, including sensing means mounted on said carriage behind said arrester arm in the direction of carriage advance and sensing movement of a carriage stop therepast, and adjustable delay means responsive after an adjusted delay to said sensing means for moving the arrester arm to projected position, whereby the carriage will only be arrested at one out of a predetermined number of said preset positions.

l2. The machine claimed in claim 9, including means for adjusting the relative position of said sensing means with respect to said arm in a direction parallel to carriage displacement, whereby to enable the movement of said arm to projected position in response to the sensing means to be delayed a suicient length of time to cause the carriage to be only arrested at every other preset position.

13. A frame printing machine which comprises an elongated table adapted to receive a sheet of material to be printed on; a main carriage supported for longitudinal displacement over the table; a frame carrier having a printing pattern frame and supported on said carriage for movement between a printing position in engagement with said material and a raised position; a squeegee assembly supported for horizontal traversing displacement across said frame carrier when in printing position to apply a printing substance through the pattern to said material; and means for displacing ythe carriage, frame carrier and squeegee assembly respectively; wherein said squeegee assembly comprises a squeegee carrier traversable across the frame carrier, a squeegee supporting member mounted for vertical displacement on said squeegee carrier, spring means connected to the squeegee carrier and squeegee supporting member for exerting a downwardly directed pressure on said supporting member and squeegee, and biassing means for adjusting the pressure exerted by the spring means including spring means associated with said biassing means for indicating the bias pressure exerted on the squeegee.

14. A frame printing machine which comprises an elongated table adapted to receive a sheet of material to be printed on; a main carriage supported for longitudinal displacement over the table; a frame carrier having a printing pattern frame and supported on said carriage for movement between a printing position in engagement with said material and a raised position; a squeegee assembly supported for horizontal traversing displacement across said frame carrier when in printing position to apply a printing substance through the pattern to said material; and means for displacing the carriage, frame carrier and squeegee assembly respectively; wherein said squeegee assembly comprises a squeegee carrier traversable across the frame carrier, a squeegee supporting member mounted for vertical displacement on said squeegee carrier, spring means connected to the squeegee carrier and squeegee supporting member for exerting a downwardly directed pressure kon said supporting member and squeegee, and biassing means for adjusting the pressure exerted by the spring means, including cam means on the frame carrier and a follower projecting fromthe squeegee supporting member and engageable with said cam means in opposi-l tion to said spring pressure at least one end of the traverse of the squeegee carrier.

15. The machine claimed in claim 14, wherein said cam means comprise a retractably mounted ramp up which said follower is adapted to rise at the end of said traverse and a rest member adapted to receive said follower to retain the squeegee in a raised position, and means retractably mounting said ramp to allow the follower to move past it as the squeegee carrier commences its reverse traverse.

Claims

1. A FRAME PRINTING MACHINE WHICH COMPRISES AN ELONGATED TABLE ADAPTED TO RECEIVE A SHEET OF MATERIAL TO BE PRINTED ON, A MAIN CARRIAGE SUPPORTED FOR LONGITUDINAL DISPLACEMENT OVER THE TABLE, A FRAME CARRIER HAVING A PRINTING PATTERN FRAME AND SUPPORTED ON SAID CARRIAGE FOR MOVEMENT BETWEEN A PRINTING POSITION IN ENGAGEMENT WITH SAID MATERIAL ON THE TABLE AND A RAISED POSITION, A SQUEEGEE ASSEMBLY SUPPORTED FOR HORIZONTAL TRAVERSING DISPLACEMENT ACROSS SAID FRAME CARRIER WHEN IN PRINTING POSITION TO APPLY A PRINTING SUBSTANCE THROUGH SAID PATTERN TO SAID MATERIAL, AND CONTROL MEANS FOR AUTOMATICALLY IMPARTING TO SAID CARRIAGE, FRAME CARRIER AND SQUEEGEE ASSEMBLY A CYCLIC SEQUENCE OF DISPLACEMENT INCLUDING: ADVANCING THE CARRIAGE IN STEPS TO A SERIES OF PRE-SET POSITIONS SPACED ALONG THE TABLE; AT EACH STEP MOVING THE FRAME CARRIER TO PRINTING POSITION, TRAVERSING THE SQUEEGEE ASSEMBLY ACROSS THE FRAME CARRIER, AND MOVING THE FRAME CARRIER BACK TO RAISED POSITION; AND RETURNING THE CARRIAGE TO AN INITIAL POSITION ON THE TABLE AFTER A LAST STEP OF ADVANCE.