WO2008001209A2

WO2008001209A2 - Transfer unit for transferring production component parts on automatic production machines

Info

Publication number: WO2008001209A2
Application number: PCT/IB2007/001787
Authority: WO
Inventors: Matteo Piantoni; Gabriele Pastrello; Alberto Perego
Original assignee: Gdm S.P.A.
Priority date: 2006-06-29
Filing date: 2007-06-29
Publication date: 2008-01-03
Also published as: WO2008001209A3; ITBO20060498A1

Abstract

A transfer unit (1) for a production machine (2), wherein component parts (3) are fed to a first station (4) at a speed vl, and products (7) are fed to a second station (5) at a speed,v2 ' differing from vl; the transfer unit (1) has at least one pickup head (10; 11) operated by an actuating unit.(17) to.cyclically pick up at least one component part (3) ' at the first station (4), and to transfer it onto a relative product (7) at the second station (5); and the actuating unit (17) imparting to the pickup head (10; 11), at each cycle, a variation in speed between speeds vl and v2 by means of a mechanical transmission (19a, 19b) with a variable velocity ratio, and. an electronically regulated, variable-speed motor (18a,- 18b) connected in series to the mechanical transmission (19a, 19b).

Description

TRANSFER UNIT FOR TRANSFERRING PRODUCTION PARTS ON AUTOMATIC PRODUCTION MACHINES

TECHNICAL FIELD

The present invention relates to a transfer unit for transferring production parts on automatic production machines .

More specifically, the present invention relates to a transfer unit for a production machine, in which a first conveyor feeds a succession of component parts through a first station at a given rate and at a first speed, and a second conveyor feeds a continuous succession of products through a second station at the same given rate and at a second speed differing from the first speed. The transfer unit transfers the component parts from the first to the second station, and comprises at least one pickup head movable cyclically between the first and second station, and which, at each cycle, picks up at least one component part off the first conveyor, and feeds the component part onto the second conveyor and onto a relative product. An actuating unit imparts to the pickup head a speed varying, at each cycle, between the first speed at the first station, and the second speed at the second station.

BACKGROUND ART Though suitable for transferring component parts onto products of any type, a transfer unit of the type described above is particularly advantage for use in the diaper manufacturing industry, for transferring diaper component parts onto flat diaper blanks, to which the following description refers purely by way of example.

On diaper manufacturing machines , in fact , a continuous strip of unfinished flat .diaper blanks is formed, to which finishing -component parts, such as elastic lateral strips, central inserts of absorbent material, etc., are subsequently applied.

Since the component parts and the diapers are normally of different lengths, the diaper strip and the component parts are fed to the transfer unit at different speeds having a ratio at most equal to the ratio between the two speeds . To avoid damaging the component parts and the strip, the transfer unit must therefore be equipped with pickup heads capable of picking up the individual component parts at the speed at which they are conveyed; varying, and in particular accelerating, the speed of the component parts as they are transferred; and, finally, depositing the component parts onto the strip at the same speed as the strip.

This is normally achieved by fitting the pickup heads to the driven shaft of an non-circular-gear transmission, which converts the constant-speed rotation of a drive shaft to periodically variable rotation according to a given law of motion. Non-circular gears are sometimes replaced by cam devices, which provide for achieving the same effect, i.e. varying the speed of the driven shaft and effecting purely mechanical control of the law of motion governing the pickup heads. Though effective and widely used, both these solutions have serious drawbacks, mainly due to the mechanical complexity involved, which makes them difficult to produce, bulky, and expensive.

The problem is further compounded in the case of size changes, i.e. when the length of the component parts to be applied to the diapers, or the length of the diapers themselves is changed. That is, any variation in the length ratio of the component parts and the diapers also involves a variation in the ratio between the two speeds, which means modifying the speed at which the. component parts or the diapers or^' both are fed to the transfer station, and therefore the law of motion of the pickup heads .

Given the impossibility of altering the velocity ratio of a gear transmission or cam device, size changes necessarily call for substituting a whole new gear transmission or cam device to change the law of motion accordingly. By way of a solution to the problem, it has recently been proposed to operate the pickup heads by means of a motor equipped with an electronic control device, by which the angular speed of the drive shaft, to which the pickup heads are fitted directly, can be varied periodically according to a predetermined law of motion. Moreover, in the event of size changes, the electronic control device also provides for varying the law of motion of the pickup heads by simply acting on the device control circuit variables .

Though indeed enabling fast, accurate, low-cost adjustment of the law of motion of the pickup heads, the above solution, in actual use, has in many cases proved fairly rigid, i.e. adapts poorly to size changes involving substantial variations in parameters, i.e. the speeds of the component parts and diapers . DISCLOSURE OF INVENTION

It is an object of the present invention to provide a transfer unit for transferring ^• production parts on automatic production machines, which can also be used for widely differing sizes, and, at the same time, is cheap and easy to produce.

According to the present invention, there is provided a transfer unit for transferring production parts on automatic production machines, as claimed in Claim 1 and, preferably, in any one of the following Claims depending directly or indirectly on Claim 1. BRIEF DESCRIPTION OF THE DRAWINGS A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a view in perspective of a preferred embodiment of the transfer unit according to the present invention;

Figure 2 shows a plan view of the Figure 1 transfer unit;

Figure 3 shows a side view of Figure 2; Figure 4 shows a section along line IV-IV in Figure 2;

Figures 5 and - 6 show larger-scale views in perspective of two details in Figure 1;

Figures 7 and 8 show, schematically, a sequence of operating configurations of the Figure 4 and 5 details over a complete operating cycle;

Figures 9 and 10 show graphs of the laws of motion governing the Figure 5 and 6 details in respective different operating conditions of the transfer unit according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Number 1 - in Figure 1 indicates as a whole a transfer unit for transferring production parts on automatic production machines, and in particular a transfer unit of a diaper manufacturing machine 2.

As shown in Figure 7 or 8, transfer unit 1 is designed to pick up diaper component parts 3 successively from a pickup station 4, to which component parts 3 are fed at a linear speed vl and at a given rate, and to deposit component parts 3, at a delivery station 5, onto a strip 6 comprising a continuous succession of flat diaper blanks 7 fed by a conveyor 8 "through delivery station 5 at a linear speed v2 higher than vl, and at the same rate at which component parts 3 are fed through pickup station 4.

As shown in the Figure 7 detail, component parts 3 are defined by elastic strips comprising a portion of adhesive material or Velcro, and which, when the diaper is worn, provide for connecting the two ends of the diaper to form an annular belt.

As shown in the Figure 8 detail, each blank 7 receives two component parts 3, i.e. elastic strips,^' which are applied symmetrically to respective sides of blank 7, at one end of blank 7.

In other embodiments not shown, transfer unit 1 is used to transfer component parts 3 other than elastic strips onto strip 6. For example, component parts 3 may comprise inserts of absorbent material, which are picked up one by one and deposited successively onto the centre of respective blanks 7.

Component parts 3 are fed to pickup station 4 by a suction feed wheel 9, which rotates continuously about an axis 9a perpendicular to the Figure 7 plane, and on which, as shown in the Figure 7 detail, component parts

3 are arranged in two parallel lines spaced apart by a distance substantially equal to the width of blank 7, and each comprising a succession of contiguous component parts 3.

As shown in Figures 1, 2 and 3, transfer unit 1 comprises two suction pickup heads 10 and 11. Head 10 is in the form of a curved tile, and is connected rigidly to one end of a sleeve 12, which extends through a hole formed in a frame 13, and is fitted in rotary manner to a fixed shaft 14 to rotate about an axis 15 parallel to axis 9a, and to move pickup head 10 along a circular path P coaxial with axis 15 and extending through pickup station 4 and delivery station 5.

. Pickup head 11 is also in the form of a curved tile

^■, similar . to that of pickup head 10, and is connected rigidly to one end of ^'a sleeve 16 mounted concentrically and in rotary manner on sleeve 12 to rotate about axis

15 and move pickup^' head 11 along path P.

As shown in Figures 2 and 3, the end of sleeve 12 fitted with pickup head 10 projects axially from the end of sleeve 16 fitted with pickup head 11; and pickup heads 10 and 11, which are the same length measured along axis 15,- are positioned on respective sleeves 12 and 16 so as to be aligned transversely about axis 15.

With reference to Figure 4, pickup heads 10 and 11 have respective outer suction surfaces having the same curvature, and which are moved, by rotation of relative sleeves 12 and 16, along the same imaginary cylindrical surface coaxial with axis 15.

As shown in Figure 1, transfer unit i comprises an actuating unit 17, in turn comprising two motors 18a, 18b for powering respective pickup heads 10, 11 via respective identical transmissions 19a, 19b located, together with motors 18a, 18b, on the opposite side of frame 13 to pickup heads 10 and 11.

The actuating unit also comprises an electronic central control unit 20 connected to and for controlling motors 18a, 18b to rotate the relative drive shafts 21a, 21b at a constant or cyclically variable speed about respective axes 22a, 22b parallel to axis 15.

With particular reference to Figures 2 and 3, transmission 19a is interposed between motor 18a and sleeve 12 to transmit motion to pickup head 10, and comprises an eccentric-gear train 23a and a circular- _.gear train 24a.

More specifically, eccentric-gear train 23a comprises a drive gear fitted to drive shaft 21a and meshing with a driven gear for transmitting motion, by means of a shaft 25a parallel to drive shaft 21a, to a first cylindrical gear, which forms part of gear train 23a and, in turn, meshes with a second cylindrical gear fitted to the free end of sleeve 12.

Transmission 19b is similar to transmission 19a, is interposed between motor 18b and sleeve 16 to transmit motion to pickup head 11, and comprises an eccentric- gear train 23b and a circular-gear train 24b.

More specifically, eccentric-gear train 23b comprises a drive gear fitted to drive shaft 21b and meshing with a driven gear for transmitting motion, by means of a shaft 25b parallel to drive shaft 21b, to a first cylindrical gear, which forms part of gear train 23b and, in turn, meshes with a second cylindrical gear fitted to the free end of sleeve 16.

Actuating unit 17 operates pickup heads 10 and 11, so that each pickup head 10, 11 has a speed equal to vl at pickup station 4, and a speed equal to v2 at delivery station 5. The speed of each pickup head 10, 11 therefore varies cyclically • as it rotates about axis 15. More specifically, each pickup head 10, 11 maintains a constant speed equal to vl as it travels through pickup station 4; is accelerated, from pickup station 4 to delivery station 5, to a speed equal to v2; maintains speed v2 as it travels through delivery station 5; and is decelerated from delivery station 5 to pickup station

4, to return to speed vl upstream from pickup station 4.

As explained below, pickup heads 10, 11 are operated so that, when one of the two pickup heads 10, 11 is located at pickup station 4 to receive two component parts 3, the other pickup head 11, 10 is located at delivery station 5 to release the two component parts 3 picked up previously onto a relative blank 7.

With reference to the operating configurations in Figures 7 and 8, at the start of the operating cycle (position a) ) , pickup head 10 is located at pickup station 4 and has a speed vl, while pickup head 11 is located at delivery station 5 and has a speed v2. The next instant (position b) ) , pickup head 10 is rotated anticlockwise towards delivery station 5, and pickup head 11 is rotated anticlockwise towards pickup station 4; during which movements, pickup head 10 is accelerated from speed vl, and pickup head 11 is decelerated from speed v2. Since the initial speed of pickup head 11, however, is higher than that of pickup head 10, the distance between pickup heads 10, 11 at this stage is gradually reduced till it eventually reaches a minimum close to pickup station 4;^" from which point on, the two pickup heads begin moving away from each other (position c) ) till they eventually reach the configuration (position d) ) in which pickup head 10 is located at delivery station 5 and has a speed v2 , and pickup head 11 is located at pickup station 4 and has a speed vl .

The cycle is completed by pickup head 10 returning (positions e) , f) ) to pickup station 4 (and being decelerated in the same way as described for pickup head 11) , and by pickup head 11 returning to delivery station 5 (and being accelerated in the same way as described for pickup head 10) .

The variation, at each cycle, in the speed of each pickup head 10, 11 from speed vl at pickup station 4 to speed v2 at delivery station 5, and vice versa, is imparted to pickup head 10, 11 by actuating unit 17 in two series-connected stages : a first stage comprising mechanical transmission 19a, 19b, which produces a first variation in speed by virtue of the variable velocity ratio of eccentric-gear train 23a, 23b; and a second stage comprising motor 18a, 18b, which produces a second variation in speed by virtue of electronic central control unit 20, which provides for obtaining a speed of drive shaft 21a, 21b varying cyclically according to a given law of motion.

Since drive shafts 21a, ^■ 21b transmit motion directly to respective eccentric-gear trains 23a, 23b, it follows that the final variation in the speed of respective pickup head 10, 11 equals the sum of the partial variations in speed produced in the above two stages . Moreover, the variation in speed produced by eccentric-gear trains 23a, 23b is fixed, being a function of the gear ratio; and the variation -in the speed of drive shafts 21a, 21b is variable, i.e. can be adjusted electronically by means- of central control unit 20.

Given the fixed variation in speed produced by the velocity ratio of the eccentric gears,- the variation in the speed of_. each- pickup' ^'head .10,^•; II^' can therefore be. adjusted electronically, . working- on the part of the variation in speed produced by the law of motion of drive shafts 21a, 21b.

The advantage of the present invention will be clear from the foregoing description. Since the final law of motion governing pickup heads 10, 11 equals the sum of a "mechanically" achieved and an "electronically" achieved law of motion, speed can be varied over an extremely wide range, and the cyclic variation in speed 5 can be adjusted electronically with no complicated, high-cost alterations to the mechanical part of the transmission.

This is particularly advantageous in the event of size changes, i.e. to the size of component parts 3 or

10 blanks_.7 or both.. . ^•

That is, since the feed rate of- component parts 3 through' pickup station 4, and the feed rate of blanks 7 through delivery station 5 must necessarily be- the same, a change in size involves a variation in at least one of

1.5 speeds vl , v2.

Consequently, the variation in the speed of pickup heads 10, 11, i.e. acceleration and deceleration of pickup heads 10, 11 to pass from one speed to other, must also be adjusted.

20 By virtue of the two stages described above, the ■ variation in speed is adjusted by simply- adjusting the ' /output of. motors 18a, 18b electronically. In other words, the desired variation in speed is achieved by adjusting the law of motion of drive shaft 21a, 21b so

25 that its cyclic variation in speed, added to the cyclic variation in speed produced by respective eccentric-gear train 23a, 23b, equals the desired variation in speed

(acceleration/deceleration) of ^• respective pickup head 10 , 11 .

Adjustment is therefore electronic, and involves no change of eccentric-gear trains 23a, 23b.

For example, Figures 9 and 10 show graphs of the laws of motion of pickup heads 10 and 11 relative to two size changes. More specifically, Figure 9 relates to a size change in which the same component parts 3 are applied first to blanks 7 having a length and then to blanks 7 longer than before; and Figure 10 to a size change • in which the same blanks 7 are fitted first with component parts ^'-3 having a length and then with component parts 3 shorter than before.

In both cases, three laws of motion are shown : the law of motion produced by motor 18a, 18b, which varies as a function of the size change (the continuous line shows the law of motion before the size change, and the dash line the law of motion after the size change) ; the law of motion produced by -transmission 19a, 19b, which does not vary; and the final law of motion, which equals ■ the sum of the other two . • . . -

In the Figure 9 case,^{' '} for a ^' given speed vl of component parts 3 , a reduction in the length of blanks 7 calls for a reduction in speed v2 of blanks 7, so, at each cycle, pickup heads 10, 11 are accelerated from speed vl to a speed v2 ' lower than v2 , and decelerated from speed v2 ' to speed vl (see final law) .

In the Figure 10 case, for a given speed v2 of blanks 7 , a reduction in the length of component parts 3 calls for a reduction in speed vl of component parts 3, so, at each cycle, pickup heads 10, 11 are accelerated from -a. speed vl', lower than vl, to speed v2 , and decelerated from speed v2 to speed vl' (see final law) . To conclude, it should be pointed out that, in other embodiments not shown, transfer unit 1 may comprise one pickup head 10 or 11; in which case, actuating unit 17 comprises one motor 18a or 18b, and one transmission 19a or 19b. In one variation, ~the pickup heads may be more than two in number, and may be arranged in two opposite pairs and connected to the same sleeve, or may be independent of each other.

In both the above cases, however, the cyclic variation in speed of the pickup head/s, in ^'the event of a size change, is adjusted in the same way as in the example described and illustrated.

Finally, it should be pointed out- that the above • description ; relative to ^■ transfer' unit 1 of diaper manufacturing machine 2 also applies to a transfer unit used on any production machine, for transferring any component parts 3, traveling at a speed vl, onto any respective products 7 traveling at a speed v2 higher or lower than speed vl .

Claims

1) A transfer unit for transferring production parts on automatic production machines (2), comprising at least one pickup head (10; 11) for transferring said

• parts, and an actuating unit (17) for operating the pickup head (10; 11); the transfer unit (1) being characterized in- that the actuating unit (17) comprises a ^' first and a second stage connected in series to the pickup head (10; 11) to impart to the pickup head (10; 11) a first and a second cyclic variation in speed respectively; the second stage comprising electronically regulated, variable-speed drive means (18a, 18b, 20) .

2) A transfer unit for a production machine (2), wherein a first conveyor (9) feeds a succession of component parts (3) through a first station (4) at a given rate, and at a first speed (vl), .and a second conveyor. (8) feeds a continuous^' succession of products (7) through a second station (5) at the same given rate and at a second speed (v2) differing from the first speed (vl) ; the transfer unit (1) transferring the component parts (3) from the first to the second station

(4, 5) , and comprising at least one pickup head (10; 11) movable cyclically between the first and second station (4, 5) to pick up, at each cycle, at least one component part (3) off the first conveyor (9), and to feed the component part (3) onto a relative product (7) on the second conveyor (8); and an actuating unit (17) for imparting to the pickup head (10; 11) a speed varying, at each cycle, between the first speed (vl) at the first station (4) , and the second speed (v2) at the second station (5); the transfer unit (1) being characterized in that the actuating unit (17) comprises a first and a second stage connected in series to the pickup head (10;

11) to impart to the pickup head (10; 11) a first and a second cyclic variation in . speed respectively; the

^■ -second . stage comprising electronically ^' regulated, variable-speed drive means (18a, 18b, 20)-.

3) A unit as claimed in Claim 1 or 2 , wherein the first cyclic variation in speed produced by the first stage is predetermined and invariable.

4) A unit as claimed in Claim 3, wherein the first stage comprises a mechanical transmission (19a, 19b) having a variable velocity . ratio to produce the first cyclic variation in speed.

5) A unit as claimed in Claim 4, wherein the mechanical transmission (19a, 19b) comprises an eccentric-gear train (23a, 23b) .

6) A unit as claimed in any one of Claims 1 to 5, wherein the drive means (18a, 18b, 20) comprise at least one motor (18a; 18b) ; and an electronic central control unit (20) connected to the motor (18a; 18b) to produce the second cyclic variation in speed, and to modify the second cyclic variation in speed in response to a variation in the first or second speed (vl; v2) or both.

7) A unit as claimed in Claim 2, and comprising two pickup heads (10, 11) movable successively between the first and second station (4, 5) , so that, when one pickup head (10; 11) is located at the first station

(4), the other pickup head (11; 10) is located at the

5 second station (5) , and vice versa.

8) A unit as claimed in Claim 7, wherein the pickup heads (10, 11) are operated independently of each other.;

^■ . each pickup head (10; 11) being^' associated with _a respective. first stage and a respective second stage.

10 9) A unit as claimed in- Claim 8, wherein the pickup heads (10, 11) travel along a substantially circular path coaxial with a fixed axis (15) and extending through the first and second station (4, 5).

10) A unit as claimed in Claim 9, wherein . the 15 pickup heads (10, 11) are mounted on respective parallel

^■ shafts (12, 16) coaxial with said fixed axis (15).

11) A unit as claimed in Claim 10, wherein said shafts (12, 16) are concentric.

12) A unit as claimed in Claim 11, wherein each 20 second stage comprises a variable-speed motor (18a;

18b) , and each first stage comprises an eccentric-gear train (23a; 23b) , in turn comprising a noncircular drive gear fitted to an output shaft (21a, 21b) of said motor (18a; 18b) .

25 13) A unit as claimed in Claim 12, wherein each first stage also comprises a circular-gear train (24a;

24b) , in turn comprising a drive gear meshing with a

^• driven gear of the respective eccentric-gear train (23a,- 23b) , and a driven gear fitted . to . a respective said shaft (12; 16) . ^{• ■■} . ^{' ■} /^■ •^' .^'

14) A unit as claimed in any one of Claims 7 to 13, wherein the first speed (vl) is lower than the second

5 speed (v2) .

15) A unit as claimed in any one of Claims 7 to 14, wherein the pickup heads (10, 11) are suction pickup

^{■ ■} heads. ^•■ . ^{• '} . .^{" ■}

16) A unit as claimed in any one of Claims 7 to 15,0 wherein the component parts are diaper component parts

(3), and the products are flat blanks (7) of unfinished diapers .

17) A unit as claimed in Claim 16, wherein the component parts (3) are adhesive elastic strips. 5 18) A. unit as claimed in any one' of Claims 7 to 17, wherein the component parts (3 ) are arranged in- two . parallel lines on the first conveyor (9); the or each pickup head (10; 11) picking up a pair of component parts (3) at each cycle, and depositing the picked up0 pair onto a respective blank (7) .

19) An automatic production machine comprising a transfer unit (1) as claimed in any one of Claims 1 to 18.

20) An automatic production machine for producing5 diapers, and comprising a transfer unit (1) as claimed in any one of Claims 1 to 18.