CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of

U.S. Serial No. 08/277,614, filed July 20, 1994 (Attorney Docket No. 10319US01 - Corporate Docket No. TRX-0040) .

TECHNICAL FIELD

The present invention relates to a belt driven linear transport apparatus. More specifically, the present invention relates to an apparatus for linearly driving a carton engagement mechanism in a packaging machine.

BACKSROTOP

Packaging machines are known that integrate the

various components necessary to fill and seal a container into a single machine unit. This

packaging process, generally stated, includes

feeding carton blanks into the machine, sealing the

bottom of the cartons, filling the cartons with the

desired contents, sealing the tops of the cartons,

and then off loading the filled cartons for shipping.

Many packaging machines require one or more

linearly driven mechanisms that assist in the

various packaging processes. One such mechanism is

set forth in U.S. Patent No. 4,712,665 to McDonald

et al. The '665 patent illustrates a container

lifting mechanism that includes a vertical tube

actuator that is slidably mounted in bearings within

a fixed sleeve. A second vertical tube actuator is

slidably mounted in bearings within the first

vertical tube actuator so as to have independent

vertical movement relative thereto. Vertical linear

movement of the carton is accomplished by hydraulic

activation of the first and second vertical tube

actuators.

Another linearly driven mechanism for use in a

packaging machine is set forth in U.S. Patent No.

4,738,077 to akbayashi et al. The *077 patent

illustrates an apparatus for forming containers,

particularly gable top containers. The apparatus

uses a linearly driven fork that pre-folds opposed

side panels of the gabled portion of the container.

The linear movement mechanism that is used to

linearly drive the fork is hydraulically actuated.

In addition to the foregoing hydraulically

operated linear actuators, other linear drive

mechanisms may be utilized in packaging machines.

Such mechanisms include ball screws and linear

motors.

Trends within the field of packaging machines

point toward increasingly high capacity machines

intended for rapid, continuous filling and sealing

of a very large number of identical or similar

packaging containers, e.g., containers of the type

intended for liquid contents such as milk, juice,

and the like. The increased throughput and

decreased size requirements have increased the

demands that are placed on the linear drive

mechanisms that are employed. For example, high

precision linear movement with little allowable

backlash is often desirable and/or required.

Likewise, low mass actuators are desirable to

facilitate high speed movement of the driven

components.

Additional limitations on the linear actuators are imposed by virtue of the hygienic nature of the packaging process. The linear actuators must be designed to limit their contamination of the interior of the packaging machine and, further, must be easily cleaned.

SUMMARY OF THE INVENTION

A linear drive apparatus for moving a carton in a packaging machine from a first position to a

second position is set forth. The apparatus includes first and second spaced apart guide rods

and an engagement assembly that is disposed between

and slidably engages the guide rods. The engagement assembly is adapted to engage one or more cartons

for movement between the first and second position. The apparatus further includes a drive shaft onto

which a drive roller is disposed for co-rotation. A first drive belt is connected to the drive roller

and disposed about the drive roller in a clockwise

direction at a first end thereof while a second end of the first drive belt is connected to a first portion of the engagement assembly. A second drive

belt is connected to the drive roller and disposed about the drive roller in a counter-clockwise

direction at a first end thereof while a second end

of the second drive belt is connected to a second

portion of the engagement assembly opposite the

first portion of the engagement assembly. The rotation of the drive shaft in a clockwise direction

causes linear movement of the engagement assembly in

a first direction along the guide rods and the

rotation of the drive shaft in a counter-clockwise

direction causes linear movement of the engagement

assembly along the guide rods in a second direction

opposite the first direction.

In accordance with one embodiment of the

apparatus, the engagement assembly includes first

and second legs slidably engaging the first and

second guide rods. A bar extends between the first

and second legs and, for example, may include one or

more forked folder arms that respectively engage and

pre-fold a carton. One or more carton grippers that

grip the fin of a gabled section of the carton may

also, or in the alternative, extend from the

engagement bar. Other carton engagement adaptations

are also suitable for use in the disclosed

apparatus.

In a still further embodiment of the apparatus,

a further drive roller is disposed for co-rotation

with the drive shaft. A further pair of drive belts

extend from the further drive roller, one belt

extending from and about the further drive roller in

a clockwise direction and the other belt extending from and about the further drive roller in a

counter-clockwise direction. Both belts extend from

the further drive roller to engage respective portions of the engagement assembly. The points of engagement between all of the drive belts and the

engagement assembly form the corners of a parallelogram, such as a rectangle.

The apparatus may be subject to control by a control system that controls the rotation of the

drive shaft. The control system may include a servomotor connected to rotationally drive the drive shaft and a servo amplifier connected to control the

operation of the servomotor. A programmable axis

manager ("PAM") may be connected to control the operation of the servo amplifier to cause the servomotor to execute user programmed motion

profiles.

Other objects and advantages of the present

invention will become apparent upon reference to the accompanying detailed description when taken in

conjunction with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGs. 1 and 2 are perspective views of one

embodiment of a belt drive linear transport

mechanism.

FIGs. 3 and 4 illustrate one type of connection

that provides sliding engagement between the legs

and guide rods.

FIGS. 5 and 6 are perspective views of a carton

lifter mechanism employing a belt driven linear

transport mechanism.

FIG. 7 is a perspective view of a carton

lifter/pre-folder employing a belt driven linear

transport mechanism.

FIG. 8 is a schematic block diagram of one type

of control system for driving the lifter mechanism

of FIGs. 5 and 6.

FIGs. 9-11 are graphs illustrating motion

profiles that can be used in the control system of

FIG. 8 to drive the lifter mechanism of FIGs. 5 and

FIG. 12 is a schematic block diagram of one

type of control system for driving the lifter/pre-

folder illustrated in FIG. 7.

FIGs. 13-18 are graphs illustrating motion

profiles that can be used in the control system of

FIG. 12 to drive the lifter/folder mechanism of FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A linear drive mechanism, shown generally at

10, is illustrated in FIGs. 1 and 2. The drive

mechanism 10 includes an engagement assembly 15.

The engagement assembly 15, in turn, includes a

horizontally disposed engagement bar 20 and a pair

of spaced apart vertical legs 30 extending from the

engagement bar 20. The bar 20 includes a plurality

of pegs 40 that extend horizontally to engage, for

example, various carton engagement attachments. A

pair of vertically disposed guide rods 50 extend

from a base 60 and engage the vertical legs 30 at

portions 32, 34, 36, and 38 in a manner that allows

the vertical legs 30 to slide along the guide rods

50.

A pair of drive rollers 70, 75 are disposed on

opposite ends of a shaft 80 in a region exterior of

the guide rods 50 for co-rotation with the shaft 80.

Each of the drive rollers 70, 75 has a respective

drive belt 90, 95 that extends about the respective

drive roller 70, 75 in a clockwise direction to

engage respective connecting tabs 100 on the bar 20.

Each of the drive rollers 70, 75 also has a

respective further drive belt 110, 115 that extends

about the circumference of the respective drive

roller 70, 75 in a counterclockwise direction to

engage a respective connecting tab 120 on the

vertical legs 30. The tabs 100 and 120 may lie in

the same vertical plane and further may be disposed

at the corners of a parallelogram, shown here as a

rectangle.

The slidable engagement between the vertical

legs 30 and guide rods 50 is illustrated in FIGs. 3

and 4. Each of the legs 30 may include a forked

protrusion 125 that, for example, is welded as part

of the leg 30. The guide rod 50 sits in a channel

130 defined by forks 135. A pair of bushings 140

are disposed on opposite sides of the guide rod 50

in a direction transverse to the forks 135 and are

secured, for example, by nuts and bolts, to the

forks 135. The bushings 140 may be made from a material such as UHMW or nylon. Other materials are likewise suitable for such use.

Operation of the belt drive mechanism can be

understood with reference again to FIG. 1. In operation, the shaft 80 is driven, for example, by a servomotor, in a cyclic fashion in both the

clockwise and counterclockwise directions. When the shaft 80 is rotated in the clockwise direction, illustrated by arrow 145, the drive bands 110, 115

become shorter and exert an upward force on vertical

legs 30 to cause the legs 30 and the bar 20 to proceed in an upward direction. At the same time, the drive bands 90, 95 are unrolled from the drive rollers 70, 75 and are effectively lengthened. When

the shaft 80 is rotated in the counterclockwise direction, illustrated at arrow 150, the drive bands

110, 115 are unrolled from the respective drive rollers while the drive bands 90, 95 are rolled onto

the respective drive rollers 70, 75. This effectively increases the length of drive bands

110, 115 and decreases the length of drive bands 90,

95 such that drive bands 90, 95 exert a downward

force on the bar 20 and cause the bar 20 and the

vertical legs 30 to slide in a downward direction

along guide rods 50. The cyclic clockwise and

counterclockwise rotation of the shaft 80 may occur

at a high rate of speed with little, if any,

backlash and with a high degree of precision of

movement. The drive shaft 80, drive rollers 70 and

75, drive bands 90, 95, 110, and 115, and engagement

assembly 15 may be made from stainless steel to

facilitate easy cleaning of the apparatus.

Breakage of any of the bands 90, 95, 110, 115

may disrupt the operation of the linear drive

mechanism 10 or may result in its complete failure.

Such a failure may disrupt the operation of the

entire packaging machine and/or may cause

significant damage. As such, a plurality of band

breakage detectors 160 are employed. The

construction, operation, and relative position of

the detectors 160 are more fully set forth in

connection with U.S.S.N. 08/277,614, filed July 20,

1994.

The linear drive mechanism 10 may be used in a

variety of different types of packaging machines and

for a variety of different purposes. One such

machine is described in U.S.S.N. 08/190,546, filed

February 2, 1994, which is hereby incorporated by

reference. The machine described in the '546

application includes two endless belt conveyors that

are vertically displaced from one another. The

conveyors transport the cartons to a plurality of

modular processing stations where the cartons are

filled and sealed. A plurality of lifting

mechanisms are employed to transfer cartons from a

conveyor at one level to another conveyor at another

level as well as for lifting the cartons during

filling and top sealing. Additionally, a pre-folder

is used to pre-fold the cartons as they are

processed within the machine.

A lifter mechanism that utilizes the presently

described drive mechanism is illustrated in FIG. 5

at 165. The lifter mechanism 165 may be suitably

substituted for one or more of the lifter mechanisms

set forth in the 546 application.

The lifter mechanism 165 is generally similar

to the mechanism 10 of FIG. 1. The engagement

assembly 15, however, includes a plurality of carton

grippers 170 that are each shaped to grasp the

bottom fin of a gabled container. FIG. 6 illustrates

the lifter mechanism 165 engaging a plurality of

gabled bottom cartons 175. The engagement between

the carton grippers 170 and the bottom fin is more

fully described in U.S.S.N. 08/315,401 (Corporate

Docket No. TRX-0044; Attorney Docket No. 10602US01) ,

entitled "Lifter Mechanism Employing a Carton Bottom

Gripper and Carton Bottom Seal Configuration for Use

Therewith", filed on even date herewith.

FIG. 7 illustrates a pre-folder mechanism,

shown generally at 180, that may be used in a

packaging machine of the type disclosed in the

aforementioned '546 application. The pre-folder

mechanism utilizes both an upper and lower belt

drive mechanism 190 and 195. The upper belt drive

mechanism 190 includes an engagement assembly 200

that slidably engages a pair of spaced apart guide

rods 210 in the aforesaid manner. The engagement

assembly 200 includes a plurality of downwardly

directed folder arms 215 secured to bar 217.

Similarly, the lower belt drive mechanism 195

includes an engagement assembly 220 that slidably

engages the guide rods 210. The engagement assembly

220 includes a plurality of upwardly directed folder

arms 225 secured to bar 230. Each of the engagement

assemblies 200 and 220 are movable toward and away

from one another through operation of the respective

belt drive mechanism 190 and 195.

Each of the upwardly directed and downwardly

directed folder arms 215 and 225 includes a body

portion 240 connected to the respective bar 217 and

230 and a head portion 245 extending from the body

portion 240. The head portion 245 has a width W

that, for example, corresponds to the width of a

carton carrier such as is shown in the previously

described ^λ 546 application. A pair of forks 250

define a generally V-shaped recess 260 in the head

portion 245 of each of the folder arms 215 and 225.

The interior sidewalls of the forks 250 that define

the V-shaped recess 260 of each folder arm 215

engage opposed side panels at the top of the

respective carton to pre-fold the carton top toward

its characteristic gabled shape. Likewise, the

interior sidewalls of the forks 250 that define the

V-shaped recess 260 of each folder arm 225 engage

opposed side panels at the bottom of the respective

carton to pre-fold the carton bottom toward its

characteristic gabled shape.

FIG. 8 is a schematic block diagram

illustrating one embodiment of a control system

suitable for operation and control of the lifter

mechanism 165 illustrated in FIG. 5. The control

system, shown generally at 260, may include a PLC

270, an industrial PC 280, and a programmable axis

controller ("PAM") 290, all of which are connected

for communication with one another in a VME bus rack

300. The PAM 290 is further connected for

communication with and for control of one or more

servo amplifiers 310 and 320, the PAM 290 being

connected respectively to each servo amplifier along

one or more lines 330, 3335, and 340 that, for

example, may be an optical ring network. Servo

amplifier 310 is connected to control the operation

of a servomotor 350 along one or more lines 360.

The servomotor 350, in turn, may directly rotate the

drive shaft 80 or rotate the drive shaft 80 through

an intermediate gear box 370. The control system

may be constructed and operated pursuant to the

teachings of U.S.S.N. 08/315,414 (Attorney Docket

No. 10623US01 - TRX-0126) entitled "Control System

for a Packaging Machine", filed on even date

herewith and incorporated by reference.

In the illustrated embodiment, the PAM 290,

servo amplifier 310, and servomotor 350 may be

selected from any number of commercially available

products, the specific interconnection being

dependent on the products selected and, further

being within the skill of those familiar with such

servocontrol systems. The PAM 290, for example, may

be a PAM available from Socapel. Similarly, the

servo amplifier 310 may be, for example, a Model ST-

1 amplifier available from Socapel. The lifter

mechanism 165 connected to servomotor 350 moves in

accordance with a desired motion profile that is

stored in the PAM 290. The PAM software executes

this motion profile through its control of the servo

amplifier 310.

Other ancillary components are also associated

with the control system 260. These ancillary

components include the PLC 270 and industrial PC

280. The industrial PC 280 may be used in the

control system 260 to control the operation of a

video monitor on an operator control panel 380 that

communicates machine status information to the user.

The PLC 270 may be connected through an I/O control

board 390 to monitor various sensors distributed

throughout, for example, the packaging machine

described in the previously mentioned '546

application and, further, to send various control

signals to the various packaging machine components.

The PLC 270 may also function to monitor keypresses

of keyswitches on the operator control panel 380, as

well as other system input. One type of PLC

suitable for such control and operation is a Model

9070 manufactured by GE Fanuc.

When the lifter mechanism 165 is used to lift a

carton for filling and sealing, for example, in the

packaging machine set forth in the previously

mentioned '546 application, the motion profile may

include four moves. The acceleration, velocity, and

position profiles are set forth in FIGs. 9 and 11.

The first motor move, shown between lines 400 and

405 of each of FIGs. 9 and 11, drives the carton

grippers 170 and cartons 175 up through the upper

band and into fill chambers for filling of the

cartons through a plurality of fill nozzles. The distance moved is sufficient to bring the carton bottoms within a few mm of the bottom of the fill nozzle. This first move drives carton grippers 170

up as quickly as possible. The accelerations have been ramped and made as small as possible to both minimize stress on the bands and couplings and to minimize demands on amplifier current. The

accelerations cannot be made smaller without

increasing the maximum velocity to levels that could require more voltage than the amplifier 310 can provide.

The second move, illustrated between lines 405 and 410, draws the carton grippers 170 down from the

fill nozzle. It begins slightly after filling begins. The second move draws the carton grippers 170 down from the fill nozzle at velocities

sufficient to keep the fill nozzle close to the

liquid level. For hygiene reasons, the carton grippers 170 are prevented from rising to levels

that immerse the outside of the nozzle in the

liquid. To minimize splashing and foam, the carton

grippers 170 move down slow enough to keep the

liquid level close to the bottom of the nozzle. The second move ends when the top sealing areas of the

cartons are in the plane of the top sealer jaws of, for example, an ultrasonic top sealer.

The third move, shown between lines 410 and 415 drives the carton grippers 170 up a length

sufficient to keep the top sealing surfaces of the carton in the same plane as the jaws of the top

sealer during jaw closure. Without this upward move of the carton grippers 170, the top sealing surfaces of the carton may slide under the sealer jaws during their closure. The third move begins when the

sealer jaws make contact with the top sealing surfaces of the carton.

The accelerations of the third move have been limited to .5g since larger accelerations may cause

the liquid to weigh more with respect to the carton.

This may cause carton bulging that, in turn, may allow an excess amount of air to be trapped in the

carton during sealing. Bulging cartons are

undesirable because they are difficult to handle

without damage and, further, because the bulging

implies an internal pressure that can abet carton

leaks, bulging also implies that there is extra

oxygen in the carton that can oxidize the container

contents. Further, food spray may result. Such

food sprays are undesirable for hygiene reasons.

The fourth move, shown between lines 415 and

420, draws the carton grippers down to their home

position sometime before the upper band moves. The

retraction move begins after the sealing jaws have

released the carton tops.

Each move of the lifter profile is principally

a 40%, 20%, 40% trapezoidal velocity profile.

However, during the time of any acceleration (or

deceleration) 20% of the time is spent ramping up to

constant acceleration. The ramping of accelerations

was done to limit jerking of the mechanism and

thereby prevent undue stress on its components.

FIG. 12 illustrates a block diagram of a

control system for use with the pre-folder mechanism

180 shown in FIG. 7. In this embodiment, servomotor

350 is connected to drive the upper drive mechanism

190 under control of servo amplifier 310 while

servomotor 430 is connected to drive the lower drive

mechanism 195 under control of servo amplifier 320.

The control system 260 is an all other respects

similar to the one illustrated in FIG. 8.

The upper and lower mechanisms 190 and 195

connected to servomotors 350 and 430 move in

accordance with a desired motion profile that is

stored in the PAM 290 which directs the servo

amplifier 310 and 320 to drive servomotors 350 and

430. The PAM software executes this motion profile

through its control of the servo amplifiers 350 and

430.

In an alternative design to the control system

260 of FIG. 12, a single servomotor may be used to

drive both the upper and lower drive mechanisms 190

and 195 with gearing disposed between the drive

shaft 500 and the drive shaft 510 to effect the

relative degree of cooperative movement.

The pre-folder mechanism 180 includes both a

top and bottom belt driven linear transport that may

each move in accordance with its own motion profile

stored in the PAM 290. The acceleration, velocity,

and position profiles for the lower pre-folder

mechanism 195 are set forth in FIGs. 13 - 15 as

applied, for example, to the packaging machine of

the aforementioned '546 application.

The lower pre-folder motion profile may include

three moves. The servomotor 430 is first driven to

lift the upwardly directed folder arms 225 to the

bottoms of the cartons in the lower conveyor band in

the time illustrated between lines 520 and 525 of

each of FIGs. 13 - 15. The second move, shown

between lines 525 and 530, drives the folder arms

225 up through the level of the lower conveyor band

to the level of the upper conveyor band so that the

bottom sealing areas of the cartons are in the same

plane as the jaws of the horn and anvil of an

ultrasonic bottom sealer. The third move, shown

between lines 530 and 535 returns the upwardly

directed folder arms 225 to their home position.

The third move begins when the jaws of the bottom

sealer make contact with the bottom sealing areas of

the carton.

Each move of the lower pre-folder drive profile

is a l/3rd, l/3rd, l/3rd trapezoidal velocity

profile. However, during the time of any

acceleration (or deceleration) 20% of the time is

spent ramping up to constant acceleration and 20% of

the time is spent ramping down to zero acceleration

thereby to limit jerking motions.

The motion profile for the upper belt driven

linear transport mechanism of the upper pre-folder

are illustrated in FIGs. 16 - 18. This profile may

include four moves. The first servomotor move,

shown between lines 550 and 555 of each of FIGs. 16

- 18 drives the downwardly directed folder arms 215

down through the level of the upper conveyor band

into the level of the lower conveyor band at the

level of the tops of the cartons in the lower

conveyor band. Since the upwardly directed folder

arms 225 arrive at the carton bottoms at

approximately the same time, the bottom lift forks

and the pre-folder forks secure the cartons.

The second move, shown between lines 555 and

560, draws the folder arms 215 back up to the level

of the upper conveyor band. This second move is

executed at the same time as the second move of the

bottom pre-folder described above so that the

cartons remain secure in the grips of both sets of

folder arms 215 and 225 as they are transported

between the conveyors. The third move, shown

between lines 560 and 656, drives the folder arms 215 down a length sufficient to keep the bottom

sealing surfaces of the carton in the same plane as the bottom sealer jaws during jaw closure. Without this downward move of the folder arms, the bottom

sealing surfaces of the carton may slide over the

sealer jaws during their closure. The third move begins when the sealer jaws have made contact with

the bottom sealing surfaces of the carton.

The fourth move, shown between lines 565 and 570 draws the folder arms 215 clear of the carton

tops and returns them to their home position

sometime before the upper conveyor band indexes the cartons from the pre-folder station. The retraction

move begins after the sealer jaws have firmly gripped the carton bottoms.

Each move of the upper pre-folder motion

profile is basically a l/3rd, l/3rd, l/3rd trapezoidal velocity profile. During the time of

any acceleration (or deceleration) 20% of the time

is spent ramping up to constant acceleration and 20%

of the time is spent ramping down to zero