CA1282438C - Handling of sheet materials - Google Patents

Abstract

ABSTRACT

Improvements Relating to the Handling of Sheet Materials.
The invention provides that a vacuum drum with rows of vacuum ports over its surface is used to transport self adhesive labels from a first location at which the labels are applied (adhesive surface outwards) to the drum to a second location at which the labels are detached from the drum. The labels are held to the drum during the transport by applying vacuum to the ports until the label reaches the second location, when the first and second rows of ports at the leading edge of the label are applied with air under pressure, the pressure of the air supplied to the second row of ports being less than that supplied to the first row and slightly in advance in the time sequence, so that the edge of the label is slightly inwardly of the adjacent label extremity, initially lifted from the drum and then said extremity is blown sharply away from the drum providing effective, positive and reliable detachment of the labels from the drum.

Description

1~8~438 Improvements Relating to the Handling of Sheet Materials 05 This invention relates to the handling of sheet materials, and more particularly conce~ns the handling of indi~idual sheet artic}es such as labels~ tickets, coupons or the like by appropriate maohinery in order to transport and transfer the sheet materials from o~e surface or location to another.

In, for exampleq the application of individual labels to bottle~ or articles in a mechani~ed process, there arises freq~ently the need to handle and transfer the labels from one location to anotherD Specifically, in an area in which we are interested, individual ~abels are cut from a web of material leaving a skeletal wast0. and the labels are held by mean$ of a drum or plate which moves so as to moYe the cut labels in a path whioh is dif~erent from the path of travel of the ~keletal waste~ Sub~equently, the :Labels are re~oved from this oarrier and are either applied directly to articles or are kransferred by an intermedi~te carrier to a loaation where they are applied to said articles.
z5 In this connection, one face of the labels ~ay be provided with an ~dhesiYe which is either pre-aPplied or subsequently appliedO The form o~ adhesiYe is ~ot of particularly ~nate~rial considera~ion in rel~tion to the present invention, but i~ may be for example 30 pressure sensitive adhesive or heat activated adhesive or indeed water activated adhesive and will be to the outer surfaee of the label in relation to the carrier which transports the label.

In our European Patent Application No. 8230~5057 we have set forth one method of detaching labels from a rotary vacuum drun~. The labels are held to the drum~

~2~3X~3~3 ' surface 'chrough suitable ports to which a Yacl1um is app~!iedq but when the label reaches a posi~ion wbereat detachment is required. air under pressure is applied through some of 'chese p~rts in an attempt t~ blow the 05 label from the drum surface and directl~ onto an artiele moving in synchronism with the drum~ It has been found in experimenting with ard developing such a sy~stem that because of the por'c design size of aperture. in fact there is no blowing away OI the label from the drum, but rather what appears to ~appen is that a film or layer of air exist~ under t~e label in 'che region of the ports through which the pressure air i5 blown. and the label simply lifts from the drum surfac~, to a very small extent i~e. of the order ~f' 1 15 mm. and is not physically blown ah~ay ~rom the drum ~urface~ which indeed is what is require~.

In con~equenae., in some cases where the labels should leave the drum. and it should be borne in mind that the 20 drum may be handling labels at 'che rate o~ 200 per minute, such labels do not leave the drum and consequently there is fouling and severe ~lockage of the apparatu~.
.
The present ln~ention was made in an eîfort t~ overcome ~this diffi~ulty~ and whilst its i0mediate ~se will be in relation to the apparatus in which we are interested i.e. the handling of labels by rotary vaouum drums~ it will be appreciated that it is not neces ary that the 39 invention should be so limited to suoh speoific appl i cati on D

Varlous experiments and trials were conduc~ed before the present invention was finally reached. In 35 particular~ in a f irst experimenS, the ports through which the air blast was conducted were surrounded by annular ports through which low pressu~e air was '~LZ~3Z'~

conducted in an effort more positively to detach the labelsO but this experiment produced no lmproYed effect~ Seco~dly, instead of utilising apertures to form the ports, the said ports were defined by sintered 05 metal plugs in an effort to provide greater air distribution, but again this experim~nt ~Jas unsuccessful~ ~hirdly, a channel was formed around the exi~ port~ in an effort to provide a body of pres~ure air ir. free space, but again this development proved ~nsuccessf~1.

The presen~ invention however has shown itself to be extre~ely useful for the purpose. and in accordance with the present invention the method comprises detaching a sheet element from a support surface having a plurality of apertures therein throug~ which pressure air oan be supplied in order to detach at least one edge of the sheet, the method residing in that pressure air is supplied to porting in a region which is inwardly spaced of the edge of the she!et material to be detached, followed by injection of higher pressure air through porting which the edge to be detached overlies, This arrangement has been shown to work extremely well insofar as when the lower pressure air is applied to the sheet inwardly of the edge thereo~, the sheet lifts from the surfaoe at that point, and when the subseq ue nt blast of air is applied to the portlng oo~ered by the edge, then that edge is positively and clearly blown away from the surface. Once the edge of the shcet material is thus separated from the sur~ace, it then becomes a relatively easy matter to control the positive displacement of the entire sheet from the surface. For example~ a paring knife edge can engage under the detached sheet edge preventing it from returning to the said surface.

~2~3Z~38 In speci~ic application, the said surface supporting the sheet will be movable, and preferably will be a rotary drum to which individual sheets are applied in - turn and are removed i n turn, and i n one exampla the said drum co~prises a vacuum drum provided with a plurality of rows of vacuum ports to which vacuum can be applied in order to hold the sheets thereto whilst the ~heet3 travel between an application location and the detachment location, but which at the detachment 10 location can become the ports which are pressuri~ed in accordance with the method of the prssent invention.

In a ~peci~ic example, if one consider~ that the drum is handling labe~ and the labels ~or simpllci~y!s ~ake l~ are re¢tangular with the loDger side~ exte~ding ax~lly of the drum, each label in relation 1;o the direction oP
. rotation of the drum will havs ~ ~sading edge and a trailing edge. In the specific applicat;ion o~ the ~ethod of the invention, the leading edge will be the 20 edge which is detached in accc,rdance with the invention, and the first ro~ of pOl't3 which is under the leading edge of the label will ~t the appropriate time have the inJection o~ air under pressure, but the second row w~ll be provided with air under presqure ~rst/ and at a difPerent ~lower ar higher) pre~sure~
Suitable coupl~ng porting must be provided on the mo~t~g~ ~or the drum to ensure t:hat thi~ happen~
because in 'che operation of th~ particular apparatus, normal ly the port~ will be connec~ed to a source of vacuum ln order that the la~el3 will be held to the drum as they ~ravel between the application location and the detachment looation, but when thè ~irst and second rows of ports reach the application location, air under pres~ure is to be supplied thereto a~
described above. Equally, the third and subsequent rows of ports covered by the label are coupled to the ~ource of pre~sure a~ kh_ said rows pass the ~2824~8 app~ication location.

The inventio also provides apparatus constructed to-operate in accordanae with the method.
û5 The method has show n itself to be extremely use~ul in high speed label application situations. especially when a rotary drum is used f or the transport of the labels between attachment and detaohment location~
10 spaced relative to the drum periphery.

The method may be used ln coniuncSion with suitable knife means to assist the detachment cf the labels ~rom ~he surface~ and such knife means m~y comprise a 15 mechanical knife member. or for exan~ple an air knife ar~angementO

It will be appreciated that the invention can be applied for the handling of other sheet elements apart 20 ~rom labelsO a~d also ~hat the labels to be handled can be of any size and configuration. ~'he labels may be the so-called patch labels or wrap round labels the latter being of a type to be wrapped completely round the articles to which they are to he app~iedi The method of the invention can be utilised for the handling of sheet materials which are ~elicate and flimqy as the vacuum and positiYe pres~ures can be controlled as desired. Also. as air will be the most 30 likely gas to be used for the creation of the vacuum and air pressure. it is to be appreciated that any gaseous medium can be used.

An embodiment of the invention will now ~e described, 35 by way of exampleO with reference to the accompanying diagrammatic drawings. wherein:-~ ~8Z438 FigD 1 is a perspective vi ew of an arranger~en~according to the present invention;

Figo 2 is a development Yiew show ing the vacuum drum, 05 and the valve drum in opened out condition; and Figs~ 3 and 4 show how a label is separated from tbe va~uum drum in aocordance with the ~ethod of the inY enti os~ D
Referring to the drawings. in Fig~ 1 there is shown a vacuum drum îU which co-operates w:ith a die cutting drum 12. khese drums being rotatable as indicated by the arrows~, and defining there-between a outting lip 15 ~hrough which a web '14 having labels 16 defined thereor, pass~ B .

The web 16c is as disolosed in our European Patent Application No. 82~065057 and has pressure sensitive adhe~ive on side 18. and a re~ease ooat on ~de 20 so that tbe release coat in faet covers the label printin~
16 and enableY the web 14 to be wound intu roll form without the use of a backing web. AdditionalIy.
although lt formg ~lO part of the present invention, the 25 s~eb 14 has sprocket drive apertures .~2 along the edges ' 'chere~fD

As the web passes through the nip between drums 10 and 12. the web moving in the direotion of arrow 24. the 30 indi~idual labels 16 are cut from the web 14 so as to leave a skeletal waste 14A whioh is taken away from the nip for disposalq the labels 16 bein~ held to the drum 10 by 'che applicatlon of a vacuum to ports 26 ln the cylindrlcal surfa~e thereof to which the labels 16 are 35 he~dO When the labels 16 are so. held to drum 10. the adhesive surfaces are outermost enablin~ the labels to be applied directly to articles which ~ove into clo~e ~2l3Z43~3 proxi~ity with the surface of the drum 10 at an application location (region A in Fig. 1) so that the labels 16 oan be transferred from the drum to the articles. The eDtire prooess is a s~ontinuous process 05 in tha'c the web-14 is fed continuously and the drums 10.
and 12 are adhered continuously. thereby achieving high speeds although a step by step arran~ément can also be utilisedO

lO The running of such machinery at high speeds as can be appreciated brings problems of effici.ently separating the labels 16 from the vacuu~ drum 1(~ and the Present invention provides a method for aohiellin~ the reliable separation of the labels from t~e vacuum drum. This 15 i5 achieved in the ~ollowing manner. It will be roticed that the ports 26 are arranged in row~ 26A. 26B
.. . . .. .. .. . . .. ... . . . . . . . . . . . . . . ..
~r)d 50 ~r~. extending axially of t~e periphery of ~he drum 10 and arranged in parallel rela'..ionship. and the vacuum is applied to these ports ~hrough vacuum lines 20 30 in a vacuum valve blook 32 which remains stationary as drum 10 rotates. The vacuum l~l applied to the ports 26 between the location of ~he nip and th0 separation location A ~o that the labels 16 will be held to the drum 10 as shown. but when the leadin~ edge 16A o~ each label 16 reaches the location A~ the 'leading ports s~ch as 26A and Z6~ are supplied. instead o~ with vacuum. with air un-der pressure in order to blow the leading edge 16A away fro~ the surface of the drum 10~ and as ~he further rows of ports 26C pass the 30 release station A. so ~uch rows of ports pro~ressively are supplied with air under pres~ure in order thak there will be a continuous blowing of the label 16A
away from the drum surface throughout the arcuate extent to which the label 16 over}aps the drum 10.
In accordance w~th the present invention however. the ~equence of blowing is controlled so as to give positive displacelDen'c of the leadin~ edge 16A of the label away fro~ the drum surface. and this can best be explained by referring to Figso 2~ 3 and 4.

05 In ~ieO 2 it is seen that the ports 26A are suPplied from an inlet 34 lying relatively close to the periphery of drum ~0. and ports 26C to 26N are supplied by inlet~ 36 which are on the same patch circle as port 340 However~ ports 26B l,e. the second row of ports lO are suppl~ed from an inlet 38 which is loaated on a smaller pitch circle than ~he ports ~4 and this i5 to provide tbat air under pressure will be supplied to the ports 26B in faot fraotionally before i~ is ~upplied to the ports 26A when l~he leading edge 1fiA of 'che label ~6 15 is ~o be removed ~roo~ ~he dru~. The mek~od o~
achieYing th~s oan also be understo~d from Fig. 2 in $ah~ch the under ide of the lJalYe blook ~2 ls shown. and it will be ~e0n that there is a firs~ air pre~sure port 40 and a second air pressure port 42 these also belng 20 shown ln Fig. 10 por'c 40 lying on a pitoh oircle of 'che blook ~2 which registers with tl.ie pitch circle containing the inlets 34 and 36 in the drum 10. whilst port 42 lies on a~pitch oircle which r~glsters with the pitch ~ircle ~ontaining inlet 38 in drum 10. On the 25 undersurface of the valve bl~ck 32 there is a gallery 41l leading fro~ port 42 and extendin~ circumferen'cially of blook 32. This gallery ~4 ls arranged to register with khe inlet 38 before port ~ r~aister~ with inlet 34 when the valve block ~2 and drum 10 are 30 operationally arranRed as shown in Flg. 2.
.
As a result. when tbe machine operates. the pres~ure air supplled through inlet port 42 in the valve blook will be supplied to the inle'c 38 and ports 26B before 35 air under pre~sure is supplied throu~h Port 40 to inlet ~4 and even'cually to ports 26A. FurtherlDore. the pressure of air ~upplied to the port~ 2S~ is from a ~;
~2~3Z438 g regulated source and will be lower than that supplied to the ports 26A.

Figs. ~ and 4 show what happens as the gallery ~4 05 registers with inlet 30h and when port 40 registers with inlet 34.

In Fig. 3. which shows in cross sectional plan leadin~
edge 16A of the label lying on the drum 10 at the I0 detachment location A~ and tbe gallery 44 has registered with port 38 and has supplied air under pressure through ports 26~. The leadin~ edge t6~ ~f the label 16 has llfted from the surface of the drum 10 but only to a very s~all extentO for examPle of. ~he l~ order of 1 mm. and would remain in this condition were it not for the subsequent application of higher .. ..... . .. .. . .. . . .. . .. .. . . .. .. ... . .. . . . . .. . .. . . ... . .. . .. .
pressure air blast through the inlet 34~ and th~ 5 i~
achieved when the port 40 registers with inlet 34 to provide the condition ~hown in Fig. ~. The high 20 pressure air blast indicated by arrow 4B in Fig. 4 in is~uing through port~ 26A ca~ses the leading edge portion 16B in fact to hinge sharPly away ~rom the surface of the drum 10 as ~hown in Fi8. 4. enabling for example the insertion of a mechanlca~. par1ng knife 50 25 in~o a location between the label leading edge 16A and ,the surface of the drum 10. Continued rotation of the drum 10 ~eans ~hat the subsequent lnlets ~6 are appl~ed in turn with air under pressure pro~ressively to detach the label 16 from the drum surface.
The system as de~or~bed works excellently under test.
oonditions~ and will provide a means whereby the labels oan be detached positively and effectively and at hiBh speed so that they can be applied reliably to the 35 articles which move in synchronism therewith.

Claims (6)

1. A method of detaching a sheet element from a support surface wherein the support surface has plurality of apertures through which air under pressure can be applied, comprising the steps of:

supplying low pressure air to some of said plurality of apertures in a region which is inwardly spaced from an edge of the sheet element to be detached, and injecting air at a pressure higher than said low pressure air through other of said plurality of apertures over which the edge of the sheet element to be detached overlies, following said step of supplying low pressure air, so as to detach said edge from a detachment location of the support surface.

2. A method according to claim 1, further comprising the step of detaching a remainder of the sheet element from the sheet element from the support surface by a paring knife engaging under the edge of said sheet element which has been detached by said low and high pressure air.

3. A method according to claim 1, wherein said support surface is the surface of a rotating drum, and further comprising the steps of:

moving the surface of the rotating drum, applying individual ones of said sheet elements in turn to said drum, said drum being a vacuum drum provided with a plurality of rows of said apertures, applying a vacuum to said apertures in order to hold the sheet elements thereto while the sheet elements travel between a location where the sheet elements are applied to the vacuum drum and the detachment location, and subsequently supplying the apertures with said low pressure and higher pressure air to detach the sheet elements from the vacuum drum.

4. A method according to claim 3, wherein the sheet elements are rectangular, self adhesive labels, and further comprising the step of applying said labels to the drum with longer sides thereof extending axially of the drum and holding said sheet elements to the drum with an adhesive side therof facing away from the drum surface.

5. A method according to claim 4, wherein said edge is a leading edge of each label, a first row of said apertures being located under the leading edge of each label and a second row of apertures being located under an inwardly located part of the leading edge of each label; and further comprising the step of applying said low and higher air pressures to said second and first rows of the detachment location so as to detach the leading edge of each label from the drum surface.

6. A method according to claim 5, further comprising the step of applying a vacuum to said first and second rows of said apertures to hold the labels to the drum until the apertures reach the detachment location.