Method and machine for the robot wrapping of a palletized load with a cover made of flexible plastics material

Abstract

A wrapping machine has a transfer and accumulation device including an accumulator element on which a part of the sleeve is wound, and a mechanism for performing spreading of the open end of the sleeve after transfer to the covering station. According to the invention, a programmable control device determines the position and/or the inclination angle of the feed axis of the load by synchronizing the positioning control of the transfer device with position data of the load. This results in positioning of the transfer device according to the spatial position of the load to be packaged.

Claims

1. A method for forming and depositing a packaging cover on a palletized load with a robot, said palletized load having a longitudinal mid-axis and a transverse mid-axis perpendicular to the longitudinal mid-axis, said cover being prepared from a sleeve made from flexible plastic material wound on at least one storage reel, the method comprising: storing a predefined length of sleeve on a transfer and accumulation device with the sleeve constituting a cover closed at one end; taking up an open end of the cover opposite to the closed end of the cover; moving the palletized load to a covering area by means of a conveyor; determining a first position of the transverse mid-axis of the palletized load with respect to a feed axis of the sleeve when the palletized load is stopped in the covering area; determining a second position of the longitudinal mid-axis of the palletized load with respect to a longitudinal axis of the conveyor when the palletized load is stopped in the covering area; adjusting longitudinal and lateral positions of the transfer and accumulation device according to said first and second positions of the palletized load so that the transfer and accumulation device is above the palletized load in the covering area; adjusting longitudinal and lateral positions of take-up and spreading elements of a covering mechanism according to the position of the transfer and accumulation device; and moving the cover down and over the palletized load in the covering area, keeping the cover spread open via its four corners, wherein moving the cover from a preparation and forming station to the covering station includes positioning the cover over the palletized load based on the feed axis of the sleeve, the longitudinal mid-axis of the palletized load and the transverse mid-axis of the palletized load.

2. The method according to claim 1, comprising moving the palletized load by means of the conveyor during moving the cover down and wherein determination of the position of the load is performed by measurement of said first position of the transverse mid-axis during moving the cover down.

3. The method according to claim 1, comprising measuring angular shift between the longitudinal mid-axis of the palletized load and the longitudinal axis of the conveyor and wherein moving the cover from the preparation and forming station to the covering station includes positioning the cover over the palletized load based on the angular shift.

4. The method according to claim 1, wherein the palletized load has an offset of a top part of the palletized load with respect to the bottom part of the palletized load along the transverse mid-axis and wherein a covering mechanism adjusts fingers of a depositing arm to a transfer position of the transfer and accumulation device and the position of the load according to said functional clearance and said offset during downward movement of the cover.

5. The method according to claim 1, wherein the determining of said first and second positions of the load is made by sensors electronically connected to a control circuit of the robot.

6. A method for forming and depositing a packaging cover on a palletized load, the method comprising: providing the palletized load having a longitudinal mid-axis and a transverse mid-axis perpendicular to the longitudinal mid-axis to a covering station; providing a transfer and accumulation device configured to transfer a sleeve from a preparation and forming station comprising at least one storage reel to the covering station, the preparation and forming station defining at least a first feed axis of the sleeve, the transfer and accumulation device is mounted on an arm of a robot, the arm being mounted movable in rotation around a first rotation axis and the transfer and accumulation device is mounted moveable in rotation with respect to the arm around a second rotation axis; storing a predefined length of sleeve on the transfer and accumulation device from the preparation and forming station, the sleeve constituting a cover closed at one end; using an electronic control system to determine the longitudinal mid-axis of the palletized load and the transverse mid-axis of the load; moving the cover from the preparation and forming station to the covering station by at least one rotational movement; taking up an open end of the cover opposite to the closed end of the cover in the covering station; and moving the cover down and over the palletized load, keeping the cover spread open via its four corners, wherein the feed axis of the sleeve, the first rotation axis and the transverse mid-axis of the palletized load in the covering station are not aligned, and wherein moving the cover from the preparation and forming station to the covering station includes positioning the cover over the palletized load based on the feed axis of the sleeve, the longitudinal mid-axis of the palletized load determined by the electronic control system and the transverse mid-axis of the palletized load determined by the electronic control system.

7. The method according to claim 6, comprising providing a conveyor transporting the palletized load and measuring a first position of the transverse mid-axis with respect to the feed axis of the sleeve so as to determine longitudinal offset of the load and adjusting a longitudinal position of the transfer and accumulation device along a longitudinal axis of the conveyor with respect to the longitudinal offset of the load.

8. The method according to claim 7, wherein the covering station includes a covering mechanism comprising a depositing arms provided with fingers and wherein the method comprise adjusting the fingers of the depositing arm to the longitudinal position of the transfer and accumulation device and the position of the load.

9. The method according to claim 6, comprising providing a conveyor transporting the palletized load and measuring a second position of the longitudinal mid-axis with respect to a longitudinal axis of the conveyor so as to determine transversal offset of the load and adjusting a longitudinal position of the transfer and accumulation device along a longitudinal axis of the conveyor with respect to the transversal offset of the load.

10. The method according to claim 9, wherein the covering station includes a covering mechanism comprising a depositing arms provided with fingers and wherein the method comprise adjusting the fingers of the depositing arm to the position of the transfer and accumulation device and the position of the load.

11. The method according to claim 6, comprising providing a conveyor transporting the palletized load and measuring a first angular offset between the transverse mid-axis and the feed axis of the sleeve so as to determine an angular offset of the load on the conveyor and rotation the transfer and accumulation device around the second rotation axis so as to adjust angular offset of the transfer and accumulation device to the angular offset of the load.

12. The method according to claim 11, wherein the covering station includes a covering mechanism comprising a depositing arms provided with fingers and wherein the method comprises adjusting the fingers of the depositing arm to the transverse position of the transfer and accumulation device and the position of the load.

13. The method according to claim 6, comprising providing a conveyor transporting the palletized load and measuring a first bottom position of a bottom transverse mid-axis with respect to the feed axis of the sleeve and a first top position of a top transverse mid-axis with respect to the feed axis of the sleeve so as to determine longitudinal offset of the load and deformation of the palletized load along a direction passing through a bottom and a top of the palletized load and adjusting a longitudinal position of the transfer and accumulation device along a longitudinal axis of the conveyor with respect to the longitudinal offset of the load and the deformation of the palletized load.

14. The method according to claim 6, comprising providing a conveyor transporting the palletized load and measuring a second bottom position of the longitudinal mid-axis with respect to a longitudinal axis of the conveyor and a second top position of the longitudinal mid-axis with respect to a longitudinal axis of the conveyor so as to determine transversal offset of the load and deformation of the palletized load along a direction passing through a bottom and a top of the palletized load and adjusting a longitudinal position of the transfer and accumulation device along a longitudinal axis of the conveyor with respect to the transversal offset of the load.

15. The method according to claim 14, comprising measuring a second position of the longitudinal mid-axis with respect to a longitudinal axis of the conveyor so as to determine transversal offset of the load and adjusting a longitudinal position of the transfer and accumulation device along a longitudinal axis of the conveyor with respect to the transversal offset of the load.

16. The method according to claim 15, wherein the covering station includes a covering mechanism comprising a depositing arm provided with fingers and wherein the method comprises adjusting the fingers of the depositing arm to the transverse position of the transfer and accumulation device and the position of the load.

17. The method according to claim 14, comprising measuring a first angular offset between the transverse mid-axis and the feed axis of the sleeve so as to determine an angular offset of the load on the conveyor and rotating the transfer and accumulation device around the second rotation axis so as to adjust angular offset of the transfer and accumulation device to the angular offset of the load.

18. The method according to claim 14, wherein the covering station includes a covering mechanism comprising a depositing arm provided with fingers and wherein the method comprise adjusting the fingers of the depositing arm to the longitudinal position of the transfer and accumulation device and the position of the load.

19. A method for forming and depositing a packaging cover on a palletized load with a robot, said palletized load having a longitudinal mid-axis and a transverse mid-axis perpendicular to the longitudinal mid-axis, said cover being prepared from a sleeve made from flexible plastic material wound on at least one storage reel, the method comprising: storing a predefined length of sleeve on a transfer and accumulation device with the sleeve constituting a cover closed at one end; taking up an open end of the cover opposite to the closed end of the cover; moving the palletized load to a covering area by means of a conveyor; determining a first position of the transverse mid-axis of the load with respect to a feed axis of the sleeve when the palletized load is moving in the covering area; determining a second position of the longitudinal mid-axis of the load with respect to a longitudinal axis of the conveyor when the palletized load is moving in the covering area; adjusting longitudinal and lateral positions of the transfer and accumulation device according to said first and second positions of the palletized load during movement of the palletized load in the covering area so that the transfer and accumulation device is above the palletized load in the covering area; adjusting longitudinal and lateral positions of take-up and spreading elements of a covering mechanism according to the position of the transfer and accumulation device; and moving the cover down and over the palletized load during movement of the palletized load in the covering area, keeping the cover spread open via its four corners.

20. A method for forming and depositing a packaging cover on a palletized load with a robot, said palletized load having a longitudinal mid-axis and a transverse mid-axis perpendicular to the longitudinal mid-axis, said cover being prepared from a sleeve made from flexible plastic material wound on at least one storage reel, the method comprising: storing a predefined length of sleeve on a transfer and accumulation device with the sleeve constituting a cover closed at one end; taking up an open end of the cover opposite to the closed end of the cover; moving the palletized load to a covering area by means of a conveyor; using an electronic control system to determine a first position of the transverse mid-axis of the palletized load with respect to a feed axis of the sleeve when the palletized load is stopped in the covering area; using an electronic control system to determine a second position of the longitudinal mid-axis of the palletized load with respect to a longitudinal axis of the conveyor when the palletized load is stopped in the covering area; adjusting longitudinal and lateral positions of the transfer and accumulation device based on the feed axis of the sleeve, the first position determined by the electronic control system, and the second position determined by the electronic control system so that the transfer and accumulation device is above the palletized load in the covering area and balances functional clearance of a covering mechanism around the palletized load; and moving the cover down and over the palletized load in the covering area, keeping the cover spread open via its four corners.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other advantages and features will become more clearly apparent from the following description of an embodiment of the invention given for non-restrictive example purposes only and represented in the appended drawings, in which:

(2) FIGS. 1 to 4 describe the packaging machine according to the invention with different operating cycles;

(3) FIG. 5 represents a plane view of the robot and of the load position control system;

(4) FIGS. 6 to 9 are plane views of the machine with different sleeve feed configurations with respect to the conveyor;

(5) FIGS. 10 and 11 show elevational and side views of the transfer and accumulation device with a deformed load to be packaged;

(6) FIGS. 12 and 13 represent views of the transfer and accumulation device positioned by the arm of the robot at two height levels.

DETAILED DESCRIPTION OF THE INVENTION

(7) In the figures, a packaging machine 10 of a palletized load CH is composed of a first preparation and forming station 11 of a cover 12 from a film made from flexible plastic material, of a second covering station 13 for depositing the cover 12 on the load CH, and of a transfer device 14 between the two stations 11, 13.

(8) A conveyor 32 feeds loads CH to covering station 13 at a predefined rate.

(9) Control of the transfer device 14 is performed by a robot 15 with a multidirectional actuating arm 16 of 4-axis or 5-axis type, for example a FANUC (registered trademark) robot, controlled by a control circuit with a programmable processor.

(10) Packaging cover 12 is formed by a tubular sleeve formed by a film made from flexible plastic material, for example polyethylene or any other heat-shrink or stretchable flexible plastic material. The plastic sleeve comprises gussets in the form of a double V, and is folded flat after winding around one or two storage reels 17, 18 in first station 11. The sleeve is unwound from one of the reels 17 passing via rollers 19, and is kept in the vertical position in first station 11, with the gussets forced to the stretched position.

(11) The gusseted film can also be replaced by a simple tubular sleeve without gussets, also folded flat on reels 17, 18.

(12) In the two versions of packaging machines with a heat-shrink or cling film cover, the means of the first preparation station 11 are identical, only the fingers of the depositing arm being changed. In the case of a heat-shrink film, the depositing arm is provided with forming and pinching fingers. In the case of a cling film, the depositing arm comprises pleating and spreading fingers associated with motor-driven rollers to perform accordion pleating of the cover on the bottom part of the fingers.

(13) A transfer and accumulation device DTA formed by an accumulator element 20 and a stretching mechanism 21 with four rocker arms 22 is fitted rotating on the actuating arm 16 of robot 15. The accumulator element 20 comprises for example a motor-driven rotary roller 31 on which a part of the sleeve is wound, which is secured by a securing grip integrated in roller 31. The four rocker arms 22 of stretching mechanism 21 are equipped with grips 23 to guide and seize cover 12. The sleeve is welded transversely to form a heat-welded joint, and the accumulated element 20 is stored over a predefined length of sleeve to form cover 12.

(14) FIGS. 1 to 4 illustrated several operating cycles when preparation, transfer of cover 12, and covering on load CH are performed. These figures concern for example a packaging machine with a cling film sleeve.

(15) In FIG. 1, first preparation station 11 comprises two storage reels 17, 18, and robot 15 is placed on a support 24 between the two reels 17, 18 and facing second covering station 13. Actuating arm 16 of robot 15 is fitted with 360 rotation around a vertical axis 25 on a rotary base 26 of support 24. Actuating arm 16 can also swivel around a horizontal axis 27 to allow upward and downward movements. Multidirectional movement of actuating arm 16 is thus possible above the two stations 11, 13.

(16) FIG. 2 illustrates transfer of cover 12 wound on accumulator element 20 to second covering station 13. The four rocker arms 22 are actuated to the separated position to cause opening of the bottom free end of cover 12. Fingers 28 can separate horizontally along depositing arm 29 so as to place themselves underneath grips 23 of rocker arms 22. Depositing arm 29 is movable in the upward and downward direction by means of a vertical translation control mechanism 30.

(17) In FIG. 3, the end of cover 12 is taken up in second covering station 13 by fingers 28 of depositing arm 29. The latter is now ready to start its downward movement to progressively envelop load CH with cover 12.

(18) FIG. 4 shows the end of the covering operation, load CH being totally wrapped by cover 12. Depositing arm 29 is located in the down position, and robot 15 has moved accumulator element 20 to first preparation station to prepare a new cover.

(19) In FIG. 5, load CH to be packaged is transported by the conveyor to the covering area. A control system 34 measures the position of load CH when it is stopped. Control system 34 is provided with several optoelectronic sensors 35 arranged according to a certain network layout covering a surface above that of the top of load CH. The different sensors 35 are electrically connected by connecting wires 36 to control circuit 33 of robot 15.

(20) According to a variant, positioning of load CH can be programmed in advance after certain parameters have been stored in the control circuit. The load stops in a predefined position and the robot comes and places itself in a programmed position, without any previous measurement being required.

(21) In FIG. 6, it can be noted that the transverse mid-axis a1 of load CH is perpendicular to the longitudinal axis a2 of conveyor 32, and is separated by a distance D1 from the feed access a3 of the sleeve coming from reel 17. The latter is placed in parallel manner to the direction of movement of conveyor 32. In this case, sensors 35 measure the position of the transverse mid-axis a1 of the load to be packaged with respect to the feed axis a2 of the sleeve. Control circuit 33 of robot 15 causes movement of the transfer and accumulation device DTA of the cover to a position above the load CH, synchronizing control of positioning of said device with the measurement data of the position of the load to be packaged.

(22) In FIG. 7, reel 17 is moved through 90 extending in parallel manner to conveyor 32. An angle transmission 37 redirects the sleeve to preparation station 38, and the direction of the feed axis a3 of the sleeve is identical to FIG. 6.

(23) In FIG. 8, the longitudinal mid-axis a4 of load CH is different from the longitudinal axis a2 of conveyor 32. Control system 34 measures the position of longitudinal mid-axis a4 of the load CH to be packaged to enable longitudinal positioning of the transfer and accumulation device DTA of cover 12. This results in the possibility of eliminating the longitudinal centring device used in the prior art.

(24) In FIG. 9, the longitudinal axis a2 of conveyor 32 forms an angle A different by 90 from feed axis a3 of the sleeve. During the control and/or measurement step of the position of the load CH to be packaged, sensors 35 then perform measurement of the angular position of the two axes a1 and a2 of the load CH to enable a rotation of the transfer and accumulation device DTA to be made with respect to a vertical axis by a suitable angle. This results in the possibility of positioning cover 12 in the best direction according to the load CH to be packaged, but also of adjusting to a feed axis of the load that is not perpendicular to the feed axis of the sleeve.

(25) Fingers 10 and 11 show a load CH presenting a deformation that generally results from an offset of the top plane of the load with respect to the bottom plane. Control system 34 performs measurement of the position of the two (transverse and longitudinal) axes of the top plane of the load CH. The transfer and accumulation device DTA of the cover 12 can then be positioned according to these axes, and it enables the functional clearance to be balanced as best as possible during downward movement of the covering mechanism around the load. It also makes it possible to work with a sleeve having a parameter that is adjusted to that of the load to be packaged and therefore to reduce the quantity of cover used.

(26) In FIGS. 12 and 13, the transfer and accumulation device DTA can be positioned by arm 16 of robot 15 at a defined height level and in a space dedicated to maintenance enabling a good accessibility for maintenance operations.