FR2531380A1 - HOT SHEET MARKING MACHINE - Google Patents

Abstract

THE MACHINE ESSENTIALLY INCLUDES A TROLLEY 1 DRIVEN BY A STEP MOTOR, BY THE INTERMEDIATE OF A THREADED ROD 4. THE TROLLEY SUPPORTS A BLOCK 7 PERPENDICULARLY TO THE PATH OF THE TROLLEY; THE BLOCK SUPPORTS A SHAFT 12 ON WHICH IS MOUNTED A CHUCK 13 WHICH SUPPORTS THE PART TO BE MARKED. SHAFT 12 IS DRIVEN BY A SECOND STEP MOTOR. A CYLINDER LIFTS THE BLOCK TO APPLY THE ARTICLE ON THE CHUCK 13 AGAINST A MARKING FORM 17 WITH A THERMOPLASTIC SHEET INTERCED. STEP MOTORS RECEIVE PULSES OF NUMBERS AND FREQUENCIES SUCH AS THE ARTICLE ROLLS AGAINST THE SHAPE.

Description

Hot foil marking machines

  The present invention relates to a machine for mar-

  hot foil stamping A process of applying letters, patterns or other markings to the surfaces of plastic articles is known as hot foil stamping. In hot foil marking machines for carrying out this process, a foil which is made of a thermoplastic material or which carries a thermoplastic adhesive is introduced between the surface

  of the article and the surface of a heated form, and 11 ar-

  ticle and the form then feels tight against one tartar with the sheet inserted The surface of the form is

  made so as to only touch the sheet in the

  desired marking regions and therefore the sheet is heated and therefore adheres to the surface of the article, only in these regions The shape and the article marked with the sheet are then separated one of

The other.

  If the entire surface to which the marking is to be applied by hot sheet marking is flat,

  the marking machine can be very simple and can con-

  sister in a press comprising two plates which are movable to approach and deviate from each other in the usual manner One plate supports the article and the other supports the form and a mechanism is provided for advancing sheets or strip between the article and the form when the trays are spread apart to separate the

form and article of each other.

  It is also possible to apply the

  hot foil cages on circular peripheral surfaces of articles and machines therefor

  have a holding and heating head of a

  marking me comprising a flat marking surface, a carriage with a feed mechanism which is movable along a path parallel to the marking surface of the form, a mandrel or other support mounted to rotate on the carriage in order to hold the article to be marked, the mandrel or other support comprising a mechanism for

  rotate when the carriage moves so that the over-

  peripheral side of the article moves below the surface-

  of the form supported by there t 4 te 2 a device for advancing

  cer a sheet between the article held by the mandrel or other support and the form and a compression device for clamping an article held by the support and the form, with an interleaved sheet Machines of this kind are

  hereinafter called "of the type described".

  With marking machines, in which

  the article is moved - in relation to the form during the operation -

  marking ration, it is important that the surface of the article

  either in rolling contact with the sheet without any slipping-

  relative to the latter, because the shape, due to sliding, tends to deform or damage in any way

  another way the sheet, which affects the precision of the market

  If the outside surface of the article on which the marking is to be applied is circular, it is easy

  to obtain this rolling contact by the required speed of rotation

  tion of the mandrel or other support is in constant relation

  with the linear speed of the carriage movement and therefore

  sequent, these two speeds can be kept constant

  during the entire marking operation.

  Attempts have also been made to apply

  hot foil markings on exterior surfaces

  closed non-circular sections of articles, for example on the external surfaces of articles of elliptical or oval cross-section, or of slightly rectangular cross-section with rounded angles. To get this result without any slippage

  relative of the article surface and the market surface

  form, it is of course necessary to modify

  trust the speed of rotation of the mandrel or other support with respect to the speed of the linear movement of the carriage, and it has proven very difficult to obtain this variation with sufficient precision to obtain markings

with the desired clarity.

  Different mechanisms have been tried to pro-

  deduce the necessary variations between the two speeds, depending on the external shape of the article, but none

  has proven to be entirely safe and satisfactory in practice.

  The object of the invention is therefore to achieve a ma-

  hot stamping china of the type described, per-

  applying hot foil markings to closed exterior surfaces of non-circular items and in such a way that the marking is sharp and

satisfactory accuracy.

  To this end, and according to the invention, in a machine of the type described, the mandrel or other support is mounted on

  the trolley by which it is also mobile for

  expensive and deviate from the surface of the form at the control of the compression device, and the advance mechanism of

  carriage and support rotation mechanism are entrained

  born by electric stepper motors controlled by a control circuit which delivers pulses to the motors, the numbers and frequencies of the pulses produced for the two motors being determined according to the external shape of the article so that the instantaneous speeds movement of the carriage and rotation of the mandrel or

  other supports are such that in operation, the

  The external grace of the article is in rolling contact with the sheet throughout its movement on the surface of the form.

  It turned out that the use of electric motors

  separate step-by-step trikes to move the carriage and rotate the mandrel or other support not only provides the desired variations in the relative speeds of the

  linear motion and rotational motion, but con-

  is also a simple way to change these varia-

  at will to allow the marking operation to be carried out on articles with different external shapes, simply by re-programming the

  control circuit modifying numbers and frequencies

  pulse production frequencies for both motors.

  Preferably, the advance mechanism which places the carriage consists of a threaded rod which is rotated by one of the two stepping motors and which drives a push-button.

  evening fixed on the trolley To avoid freedom of movement

  or all in the movement of the carriage, and to thereby improve the precision of the marking of the machine,

  the pusher which is fixed on the carriage preferably comprises

  a ball that engages the threaded plug in a way

  quite similar to the steering mechanism of the circu-

  lation of balls in motor vehicles.

  To allow the mandrel or other support to approach and move away from the surface of the form, this mandrel or other support is preferably mounted to be able to rotate in a block which slides on columns or other rods, fixed on the carriage and extending in a direction perpendicular to the surface of the head, and therefore perpendicular to the marking surface

  2 o of a form supported by the t 8 te.

  In this case, the compression device which

  puts the block to move along the guide while maintaining

  nant a constant force on the block by clamping 1 article on the mandrel or other support against the form, preferably consists of a fluid pressure cylinder comprising a device by which the fluid pressure is maintained

  practically constant The fluid cylinder is preferably

  ce a pneumatic cylinder comprising a cylinder chamber connected to an air tank whose volume is large compared to that of the cylinder chamber The cylinder forms

  thus an air spring which produces an elastic force

  that practically constant throughout its course.

  The stepper motor that turns the chuck

  or other support is mounted on the block and the mandrel or support

  port itself is mounted on a shaft which is mated with

  the engine and coming out of the block in a perpendicular direction

  cular to that of the sliding movement of the block with respect to o

columns or other guides.

  It is of course essential that the outer surface of the article on which the markings are to be applied to the hot sheet has no part which is slightly concave because it is impossible to apply the sheet on a concave surface by means of a shape with a flat marking face The sheet marking is used in particular to apply markings on the surfaces of articles which are stiffened by injection of plastic material 9 and these articles necessarily have certain tolerances dimension = nelles Consequently 9 of the parts of the external surface of an article which should be flat can in fact be slightly concave and can ensure that the machine according to the invention applies markings satisfactorily on cos surfaces 9 the support is preferably in the form of a mandrel or is $ 5 inked to fit in a hollow article and which has parts = which are movable outside 4 d 9 e way quills

  are extensible G The article is then placed on the man-

  drin and the latter is expanded so that learticle

  be light as dfeor to ensure that all par-

  parts of its surface which will be slightly concave become flat or slightly convex After the mar = cuaage has been carried out the mandrel is relaxed and learti =

  key returns to its original form to be removed: d man-

drin.

  The device which advances the sheet between the

  ticle held by the mandrel or other support and the form preferably consists of two reels which receive a long strip of sheet in the form of a winding which moves from one reel to another At the end of each marking operation, when the article has been removed from the mandrel or other support, the spools are turned to move a new length of sheet "to position

on the surface of the form.

  When a marking must be applied to the rear

  o ticle with a single sheet two reels are enough

  as well as a single band But it is possible to apply

  that the marking drilled by two had several different bands

  and in this box two reels are provided for each sheet. There may for example be soft bands located side by side on the form and the latter is constituted by two marking surfaces in a same plane, one of which is covered by a band and the other is covered.

  by the other strip The trolley then moves to

  the supply and the articulation of the first on one of the marking surfaces of the form is on the other surface of mar

single pass cusage.

  Qland the machine is advanced in this way to make a marking with two separate bands and the bands are pre-perforated in the opposite direction.

  of the space of the sane where the band is first applied

  which on the article when the Iariot moves forward in the direction of the movement of the chario-; while the lair band moves in the reverse direction of the Omont muve o Charioto

  I 1 as a result; e an economy in the quantity of tape used

  made because each strip is advanced directly from its reel on the part of the surface of the form with which it is in contact when the article moves on the form If the two strips were advanced in the same direction, it would be necessary to advance a length of strip equal to the total length of the form after each marking operation and the entire length / eur of each bance would be consumed by passing the article

on her.

  In general, it is necessary that the carriage makes a movement parallel to the surface of the form in one direction to perform a marking operation, and then performs a free return movement during which no article is held by the mandrel or other support. and rotated I 1 is however possible in the machine according to the invention, to make sure that the two stepping motors are reversible and to suitably arrange the di Tositix in advance of the sheets to allow an operation marking is performed when the carriage moves relative to the form in one direction, and perform another marking operation during the return movement of the carriage in the opposite direction Of course, when this is so, the

  machine productivity has improved considerably.

  Other features and advantages of the

  vention will appear during the description which follows

  vre of an exemplary embodiment and with reference to the

  sins annexes on which: Figure 1 is a perspective view showing parts of the machine comprising two marking heads and, Figure 2 is a perspective view, similar to that of Figure 1, but without the 9 t marking

  showing two other parts of the machine that do not appear

not felt in Figure 1.

  The machine comprises a carriage 1 which is movable in one direction and in the other in the direction of the double arrow 2 on two fixed guide bars 3 The movement of the carriage 1 is controlled by a threaded rod 4 which is rotated by a first stepper motor 5 As shown in Figure 2, the stepper motor 5 is fixed to one of the two end supports 6 which support the

guide bars 3.

  A block 7 is mounted on the carriage 1 and it can move back and forth relative to the

  carriage 1, in the direction of the double arrow $ This

  This is done along two guide columns 9 and is produced by a pneumatic cylinder 10, shown in iigure 2, and whose piston rod 11 is fixed to the carriage 1 The pneumatic cylinder 10 behaves like a pneumatic spring and permanently recalls block 7 upwards, opposite carriage 1 when the machine

  works to perform hot foil marking.

  The return force is controlled by a check valve 1 Qa The cylinder 10 also has inlet conduits

  and output l Ob, l Oc so that block 7 can be lowered

  dried and raised if necessary between marking operations.

  A shaft 12 is mounted to rotate in the block 7, in a direction perpendicular to the path of the carriage 1 along the guide rods 3 and also perpendicularly

  the path of movement of the block 7 along the columns 9.

  at the shaft 12 carries one end a mandrel 13 on which, in operation of the machine, an article which must be

  marked with hot foil is mounted In this case, the item

  cle is a plastic container with a pre-

  tically rectangular with rounded corners, with a closed end and an open end The mandrel 13

  is shaped so that it fits exactly in the re-

  container to be marked As already explained, the man-

  drin 13 is extendable so that the container mounted on it can be slightly expanded in order to ensure that

  all of its exterior surfaces are very slightly

offended.

  At the end of the shaft 12 opposite the mandrel 13, there is a cam 14 which has the same external profile as that of the container mounted on the mandrel 13 The shaft 12 and

  with it the mandrel 13 as well as the cam 14 are rotated

  tation by a second stepping motor 15 supported by the block 7 by means of a structure not shown, so that the motor 15 is fixed and its shaft rotates the shaft

  12, but the engine moving with the block 7.

  As shown only in Figure 1, two tates

  marking 16 which carry forms of marking 17, to.

  their interior surfaces are mounted above the path of movement of the mandrel 13 when the carriage 1 moves in one direction and in the other along the guide bars 3 As shown in FIG. 2, a fixed guide strip 18 is mounted above the path of movement of the cam 14 and the underside of the guide strip 18 is

  in the same plane as the marking faces of the shapes 17.

  Thus, when the pneumatic cylinder 10 pushes the

  block 7 and with it the mandrel 13 with the article that it supports

  door and the cam 14 upwards, the latter engages the lower side of the guide strip 18 at the same time that the article on the mandrel 13 comes into contact with one of the forms of marking 17 In Jnsi, the the upward thrust of the pneumatic mandrel 10 is balanced by the downward forces both on the article carried by the mandrel 13 and on the cam 14, so that no twisting

  is applied to block 7 and only: 'the article on the man-

  drin 13 is pressed with uniform pressure against

  one of the forms 17 when the carriage is moving.

  Two ribbons of thermoplastic sheet are advanced c 8 te to c 8 te from supply coils to the receiving coils in the usual way, between the shapes 17 and the article on the mandrel 13 The advance mechanism

  ribbons of thermoplastic sheet is of the cou-

  rantetn Iis not shown, but one ribbon is advanced in a direction parallel to the guide bars 3 and the other ribbon in the opposite direction, also parallel to the bars

guide 3.

  The stepper motors 5 and 15 are connected to a control circuit 19 which supplies them with pulses at a frequency such that the carriage 1 is moved by the threaded rod 4 in one direction or the other along the guide bars 3 to move the article on the mandrel 13, first on the surface of one of the marking shapes

  17 then on the surface of the other form During this movement

  The motor 15 receives pulses with a frequency

  which varies so that the shaft 12 and therefore the article on the mandrel 13 are rotated at a variable speed so that at any time the article is in

  contact with the sheet and be pressed between one of the

  mes 17, the surface of the article being in rolling contact

  with two ribbons of thermoplastic sheet The

  mes 17 are arranged so that when the article is in contact with a form, one of the two ribbons is pressed against it to produce a marking and, when the article passes into the other form; the other ribbon which may be of a different color is pressed against the article and performs

a second marking.

  At the end of the movement of the cuaridt 1 in one direction, the pneumatic cylinder 10 is actuated to move the block 7 and with it the mandrel 15 downwards by the inlet

  in the Oc line and the air exhaust through the

  duite lob The article is then moved below the form plane 17 and at this time it is removed from the mandrel 13 and replaced by another similar article At the same time, the two marking tapes are moved in opposite directions so that a new length of ribbon be

  brought in the forms The ribbon which is applied to the tar-

  ticle on the left shape 17 seen in Figure 1, is moved

  cé to the right from a supply reel which is on the left and the ribbon which is applied by the right form 17 is moved to the left from a reel

  debtor who is on the right So after each operation

  ration, each ribbon does not move a distance equal to

  its length which was actually compressed by the form

  tre article If the two bands were advanced from

  dt of the same supply coil, to a m 8 me receiving coil

  this, the two bands could be moved a distance

  this equal to the combined widths of the overall shapes, with

  a space between them after each operation.

  After the movement of thermo foil tape

  plastic, -block 7 is raised again by admission

  of air through line Ob and exhaust of air through line

  pick 1 Oc then the carriage carries out a movement of re

  turn by the inversion of the imotor 5 and the motor 15 is equally

  reverse and make the same series of speed variations so that the next article rolls successively on the two forms in the opposite direction to that of the first

article.

Claims (8)

  1 hot foil marking machine   intended to apply markings on exterior surfaces   closed articles, the machine comprising a head (10) for holding and heating a marking form having a planar marking surface, a carriage (1) with an advance mechanism (4) by which it can move along a path parallel to the marking surface of the form, a mandrel or other support (13) mounted to rotate on the cnariot, intended to hold the article to be marked, the mandrel or other support (13) comprising a mechanism (12) to rotate it when the cart   moves so that the outer surface of the ar-   ticle moves on the surface of a shape held by the head, a device for advancing a sheet between an item held by the mandrel or other support and the   form, and a compression device for pressing an ar-   sheet held by the support (13) and forms it together with an interposed sheet, machine characterized in that the mandrel or other support (13) is mounted on the carriage (ij by a device (7, 9, 11) by which it is also movable in an approaching direction and   deviating from the surface of the form at the command of the device   positive compression (10), and the carriage advance mechanism (4) and the support rotation mechanism (12) being driven by electric stepper motors (5,) controlled by a control circuit (19) which delivers   to pulse motors whose numbers and frequencies   quences are determined according to the external shape   of the article so that the instantaneous velocities of the movement   carriage and rotation of the mandrel or other support   port are such that in operation, the external surface   article is in rolling contact with the foil   during its entire movement along the surface face of the form.   2 Machine according to claim 1, charac-   sée in that the advance mechanism (6) which moves 12- the enariot consists of a threaded rod rotated by one of the two stepper motors and which moves a pusher attached to the carriage.   3 Machine according to claim 2, character-   -5 sée in that the pusher which is fixed on the carriage   carries a ball which engages the threaded rod.   4 Machine according to any one of the claims.   1 to 3, characterized in that, to allow the mandrel or other support to move in a direction approaching and moving away from the head, the mandrel or other   su Epport is mounted to turn in a block that can   smooth on columns or other guides, which are fixed   on the carriage and extend in a perpendicular direction   cular on the surface of the head and therefore perpen-   dicular to the marking surface of the supported form by t 4 te.   Machine according to claim 4, characterized in that the compression device consists of a fluid pressure cylinder comprising a device by which the pressure of the fluid inside is maintained practically constant.   6 Machine according to claim 5, character-   that the fluid pressure cylinder is a cylinder   pneumatic -comprising a cylinder chamber which is re-   linked to an air tank whose volume is large compared   ratively to that of the cylinder chamber.   7 Machine according to claim 5 or 6, charac-   in that the stepping motor that turns the   mandrel or other support is mounted on the block and the   drin or support itself is my ,, é on a shaft which is coupled with the engine and leaves the block in a direction perpendicular to that of the sliding movement of the block   compared to the columns seen in other guides.   8 Machine according to any one of the claims.   1 to 7, characterized in that the support has the shape of a mandrel which is arranged to fit in an article   hollow and has parts which are movable towards ltex-   so that it is extensible   9 Machine according to any one of the claims   cations 1 to 8, characterized in that the device for advancing the sheet between the article held by the mandrel or other support and the form comprises two spools for supporting a long strip of sheet on the form of a reel , and which is moved from one reel to another and a device for rotating the reels at the end of each marking operation to bring a   new sheet length in position on the face of the form.