EP2155588A1

EP2155588A1 - A movement assembly

Info

Publication number: EP2155588A1
Application number: EP08753854A
Authority: EP
Inventors: Michael Edward Menhinick; Peter Owen Davies; Steve Maxton; Walter Unger; Murray Peter Brooks
Original assignee: Stroba Ltd
Current assignee: Stroba Ltd
Priority date: 2007-04-24
Filing date: 2008-04-24
Publication date: 2010-02-24
Also published as: AU2008241638A1; MX2009011527A; IL201750A0; WO2008130256A1; BRPI0810849A2

Abstract

A movement assembly including a drive axle (21); a number of threaded drive portions (22) operativeIy associated with the axle; two or more work articles (12) positioned in a row aligned with the longitudinal axis of the drive axle; at least one work article having a complimentary thread (18) engaged with an associated drive portion; characterised in that the movement assembly is configured such that rotation of the drive axle causes the threaded drive portions to turn and alter the spacing between the engaged work articles along the row.

Description

A MOVEMENT ASSEMBLY

STATEMENT OF CORRESPONDING APPLICATIONS

This is a cognated application based on New Zealand Patent Application Number 554717 dated 24 March 2007 and New Zealand Patent Application Number 563857 dated 28 November 2007, the entire contents of which are hereby incorporated.

TECHNICAL FIELD

The present invention relates to a movement assembly.

In particular, the movement assembly is used to control the movement of work articles and the relative spacing between these work articles. In a preferred embodiment, the movement assembly is used in article packing apparatus such as a pick and place unit.

BACKGROUND ART

In many applications it is important to control the movement of work articles in automated machinery. This is so that the work articles can be moved to a predetermined position with a high degree of accuracy. As part of this, it is often valuable to control the spacing between two or more work articles.

An example of this is in the packing of items into trays.

Where the items to be packed are consistent or uniform in size, picking and placing these items into trays can be comparatively straight forward as the machine which does this job. does not need to be adjustable for different items or grades of items. However, many items such as eggs or fruit naturally occur in a range of different sizes. Such items will typically be graded and grouped into different sizes. and then each grade will separately be placed in appropriate shaped pockets in egg cartons or in the case of fruit, into trays containing suitable inserts having a number of pockets laid out in a particular pattern. Typically these patterns are rectangular grids and each row contains the same number of pockets as all of the other rows. However, the number and pattern of the pockets will depend on the grade .of the items being run. Larger items require larger pockets and if a standard tray size is used, there will be fewer pockets in the insert of the tray and therefore a lower count. This requirement is particularly evident in case of items stacked horizontally such as kiwifruit.

Accordingly, it is advantageous if a variety of patterns of pockets can be accommodated for by the pick and place unit whereby it is adaptable to change the layout, spacing or other parameters of the work articles so that it can be pack items in the appropriate pockets.

In this application, the work articles are rows of pick up heads utilising the mechanism to grasp and release the article being packed.

There are pick and place units in existence which pick up items from a conveyor belt and place them in a pocket of a standard size. The rows of pockets typically have an X-Y pocket pattern similar to or identical to the pattern and spacing of the item on the conveyor. However this pocket pattern and the pocket size can not be easily varied due to the unit not allowing for precise controlled adjustment to • accommodate a variety of items of different size and shape.

Attempts have been made to provide pick and place units which address these concerns. An example of such a machine is disclosed in United States Patent No. 4,832,180 for a pick up device. This unit uses a head assembly having a plurality of rows of suction type "pick up heads". The spacing of pick up heads along the rows and between the rows, can be controlled by pneumatic rams to move the suction heads from a pick up position to a configuration corresponding to the layout of the container in which the articles are to be placed. The pick up assembly is moved in a rotational manner such that it can pick up articles from a delivery system such as a conveyer belt, and then subsequently place these into packaging.

The packing machine according to this document is particularly limited as it relies on the use of pneumatic rams to control the spacing of the suction cups along the rows, and the spacing of the rows themselves. These pneumatic rams involve considerable engineering and are prone to failure. Overall, they increase the cost of the packing machine in manufacturing and maintenance

In addition, the rotational movement of the head assembly limits applications in which this invention can be utilised. This is because it requires a large area through which it rotates.

Finally, due to the use of pneumatic rams, the ability to vary the spacing- of-the pick ■ up heads is limited.

It will of course be appreciated that the above example of an application of where it is advantageous to control the spacing of work articles is just one of a large number or commercially important applications. This is reflected in the number of patent applications which have been filed for devices to control the position of work articles.

United States Patent No. 4,838,515 for an article positioner and method discloses a device which can accurately control the position within three dimensions of a work tool. The device is fixed so that it can rotate through 360 degrees about a point. In order to control the positioning of the article, this uses three displacement means mounted relative to each other at equal and opposite angles to a reference axis. The movement of the displacement means, in combination with each other allows a user to control the position of a work article in three dimensions. However, this is a complicated machine which requires considerable engineering to manufacture, install and run. It is therefore beyond the reach of many businesses.

Further, this device does not have the ability to control the spacing of adjacent articles along a single axis. This is evidenced by the fact that the patent discusses only the positioning of one work article within three dimensions. Therefore it is not suitable for use in article packing apparatus.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

It is acknowledged that the term 'comprise¹ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term 'comprise' shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term 'comprised' or 'comprising' is used in relation to one or more steps in a method or process.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice. Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF INVENTION

According to a first aspect of the present invention, there is provided a method of controlling the spacing of work articles along a row, including the steps of

positioning a drive axle with respect to the row,

wherein the axle has a number of threaded drive portions operatively associated with the axle,

positioning two or more work articles such that they are substantially aligned with the longitudinal axis of the axle

wherein at least one work article has a complimentary thread engaged with an associated threaded drive portion,

characterised by the step of,

rotating the drive axle to cause the drive portions to turn and alter the spacing between the engaged work articles along the row.

According to a second aspect of the present invention, there is provided a movement assembly, including

a drive axle,

a number of threaded drive portions operatively associated with the axle,

two or more work articles positioned in a row substantially aligned with the longitudinal axis of the drive axle, at least one work article having a complimentary thread engaged with an associated drive portion,

characterised in that

wherein the movement assembly is configured such that rotation of the drive axle causes the drive portions to turn and alter the spacing between the engaged work articles along the row.

In preferred embodiment the movement assembly according to the present invention may be used in article packing units.

However, this should not be seen as limiting and alternatives are envisaged including fluid dispensing apparatus or any applications where it is necessary to control the movement of work articles relative to each other.

Throughout the body of the present specification, reference to the term drive axle should be understood as meaning a body which is capable of rotating.

In a preferred embodiment, the drive axle may be an elongate member made from a material appropriate to the stresses to which it will be subjected.

However, this should not be seen as limiting and other embodiments for the drive axle are envisaged.

In a preferred embodiment, rotation of the drive axle may be controlled by a stepper motor as known to those skilled in the art.

The use of a stepper motor is advantageous as it can accurately control rotation of the drive axle to a range of predetermined orientations. In addition, stepper motors are cost effective to purchase and reliable to run. Therefore the use of these motors reduces the overall cost of the invention to manufacture and operate. However, the foregoing should not be seen as limiting and alternate devices for controlling the rotation of the drive axle are envisaged.

Throughout the body of the present specification, the term threaded drive portion should be understood as referring to a component which has a thread as known by those skilled in the art.

Preferably, the pitch and length of the thread corresponds to the range(s) of distance through which it is intended to displace the work articles. This aspect of the present invention will become clear from the ensuing description.

In an alternate embodiment, the threaded drive portions may each have a pitch and length of variable or different dimensions. Accordingly, as the threaded drive portions rotate they change the spacing of work articles along the row by differing amounts. This aspect of the present invention will become clear from the ensuring description.

However, the foregoing should not be seen as limiting as to the pitch and length of the threads, or the combination of these used on the threaded drive portions.

In a particularly preferred embodiment, the threaded drive portions may be threaded nuts mounted on the drive axle.

However, this should not be seen as a limitation, and alternative embodiments are envisaged. These include embodiments where the threaded drive portions are integral to the body of the drive axle.

Throughout the body of the present specification, reference to the term "operatively associated with the drive axle" should be understood as meaning that as the drive axle is moved it causes a corresponding movement of the threaded drive portions.

Preferably, as the drive axle is rotated, the threaded drive portions also rotate. However, this should not be seen as limiting as other forms of movement are envisaged as within the scope of the present invention.

In a preferred embodiment, the threaded drive portions may be configured to move along the longitudinal axis of the drive axle.

In a particularly preferred embodiment, a threaded drive portion may be coupled to a first work article such that it is able to rotate as controlled by the drive axle. However, the coupling is such that the position of the threaded drive portion and first work article relative to each other along the row stays constant.

In this embodiment, the threaded drive portion also engages the complimentary thread of an adjacent work article along the row. As the threaded drive portion rotates it exerts a force against the second work article with which it is engaged. This causes the second article to move along the row at an amount corresponding to the rotation of the drive axle and the thread of the threaded drive portion.

This arrangement can be repeated along a row with subsequent threaded engagement portions being coupled to work articles while still being able to engage the complimentary thread of the adjacent work article along the row.

It will be appreciated that this arrangement causes movement of the work articles along the row for two reasons. The first is due to the rotation of the threaded drive portion and its interaction with the complimentary thread of the work article.

However as the threaded drive portions are also coupled to a work article-which is itself moving along the row, they also push the work articles with which they are engaged along the row a distance corresponding to how far the work article is moving.

It will be readily appreciated that the affect of having a series of adjacent work articles along a row connected is that the relative spacing of these work articles can be easily varied. This is achieved using the rotation of only one drive axle which causes the rotation of a plurality of threaded drive portions whether directly or indirectly connected.

In addition, the fact that the work articles are pushed along the row by two or more different factors means that a minimal rotation of the drive shaft will produce a significant change in the position of the work articles along the row.

Further, the compounding affect of the thread and the movement of the work or articles is that the relative spacing of the work articles along the row is also changed.

For instance, in an embodiment where the threaded drive portions all have a thread of the same pitch and length, the effective displacement of each subsequent work article along the row is a factor of how many work articles are being moved by the movement assembly.

This aspect of the present invention will become clearer from the ensuing description.

Throughout the body of the present specification, reference to the term "work article" should be understood as referring to a component of the invention which performs a task.

In a preferred embodiment, the work article may be a pick up head configured to engage and lift an object.

In a particularly preferred embodiment, the work article may be a suction pick up head as known to those skilled in the art.

In an alternatively preferred embodiment, the present invention may be used to control the spacing of an array of work articles. In this embodiment, the array is formed from a plurality of rows, each row having at least two work articles substantially aligned with the rows.

For instance, the array may have an XY arrangement where a plurality of work articles are positioned along a drive axle substantially aligned with the X axis.

In this array, a plurality of two or more drive axles may be positioned such that they are substantially parallel to the X axis. These drive axles will be referred to as X axles herein.

Then, another drive axle is positioned along the Y axis so that it is substantially perpendicular to the X axis. This will be referred to as a Y drive axle.

The Y drive axle has as a number of threaded drive portions operatively associated with the axle.

At least one of the X drive axles has a complementary thread engaged within an associated threaded drive portion for the Y drive axle.

Rotation of the Y drive axle exerts a force against the X axles complementary thread. This causes movement of the X axles relative to each in a manner corresponding to the direction of rotation of the Y drive axles.

This operation is substantially the same as that discussed above for the movement assembly controlling the relative spacing of work articles along a row.

It should be easily understood that the movement assembly according to the present invention can be used to control the relative spacing of work articles within a two dimensional array.

In addition, it is possible to control the relevant spacing of work articles within a three dimensional array through simply connecting appropriate drive axles to each other. However, the foregoing should not be seen as limiting, and alternatives are envisaged for the work articles including liquid dispensers or pick up heads other than those using suction to engage and lift an object.

Reference throughout the body of the present specification to the term row should be understood as being an orderly arrangement of objects.

In a preferred embodiment, the row may be a linear arrangement of objects.

However, this should not be seen as limiting and alternatives are envisaged including "Z" rows.

Throughout the body of the present specification, reference to the "work articles having a complimentary thread" should be understood as meaning work article having a thread which corresponds to that of the threaded drive portion with which it is associated.

In this embodiment, the pitch and length of the thread may also be variable so that differing spacings of the work articles can be achieved. The key factor is that the pitch and length of the thread corresponds to the thread of the threaded drive portion with which it is associated.

In a particularly preferred embodiment, one of the work articles may be fixed in position along the row to provide a reference point for movement of the other work articles.

However, this should not be seen as limiting and alternate embodiments are envisaged. These alternatives include those where two or more work articles along a row are fixed to provide more than one reference point for movement of work articles, or embodiments where no work articles are fixed along the row. In a particularly preferred embodiment, each threaded drive portion may be coupled with a first work article such that it is free to rotate. In this embodiment, the thread of the threaded drive portion is associated with the complimentary thread of another work article.

In use, the present invention relates to a method and apparatus for controlling the relative spacing of work articles along a row.

This is achieved using rotation of the drive axle which causes a corresponding rotation of the threaded drive portions which are operatively associated with the axle.

The rotation of the drive axle causes the threaded drive portion to exert a force against the work article which is associated with the drive portion.

Depending on the direction of rotation of the drive axle and the thread, the force exerted against the work article will vary. However, the effect is to move the work article along the longitudinal axis of the drive axle. It should be appreciated that this involves converting the rotational motion of the drive axle into linear motion of the work articles along the longitudinal axis of the axle.

It will be appreciated that the rotation of a single drive axle which causes a corresponding rotation in a plurality of threaded drive portions is able to exert a forces against a plurality of work articles. Therefore, this allows the present invention to vary the spacing of the work articles along the row.

In addition, the pitch and length of the thread may be varied such that rotation of the drive axle causes movement of the work articles along a differing distance.

Initially, the work articles are positioned along a row in a contracted position. In this positioned, the spacing between the work articles is at a minimum. The drive axle is then rotated causing a corresponding rotation in the threaded drive portions which are cooperatively engaged with the drive axle.

The rotation of threaded drive portions exerts a corresponding force against the work articles.

This causes the work articles to move along the row in a direction corresponding to the rotation of the threaded drive portions.

It should be appreciated, that the relative spacing of the work articles along the row is controlled by movement of a single drive axle. This is advantageous as it significantly reduces the engineering required to produce movement assemblies in comparison to pneumatic ram assemblies or scissor assemblies as known in the prior art.

In a preferred embodiment, the present invention may include a guide assembly.

Throughout the body of the present specification, reference to the term "guide assembly" should be understood as meaning a component which provides a reference point for movement of the work articles.

In a particularly preferred embodiment, the guide assembly may correspond to the row along which the relative spacing of the work articles is to be varied.

In this embodiment, the work articles are operatively coupled to the guide assembly allowing the work articles to move along the row as controlled by rotation of the drive axle and the corresponding rotation of the threaded drive portions. However, the coupling ensures that the orientation of the work articles with respect to the guide track does not vary.

Having a guide assembly is important to ensure that the work articles are not caused to rotate to a position such that they can not perform their intended function. For instance, the rotational force exerted against the work article by the threaded drive portion as it rotates with the drive axle could cause the work articles to also rotate. Firstly, this would hinder movement of the work articles along the row and the adjustment of their spacings. In addition, it could alter the orientation of the work articles such that an operative portion e.g. suction head, was not orientated so as to be able to perform its function.

Therefore, the guide track provides a reference point for movement of the work articles along the row while maintaining the orientation with respect to the row.

According to a third aspect of the present invention, there is provided a pick and place unit, characterised as having

a chassis,

at least two head assemblies configured to move relative to the chassis,

each head assembly having a row of work articles,

a movement assembly configured to control the spacing of the work articles.

Preferably, the pick and place unit according to the second aspect of the present invention may be an article packing unit configured to place objects into receptacles.

In a particularly preferred embodiment, the pick and place unit may be configured to pack kiwi fruit into boxes.

However, the foregoing should not be seen as limiting and alternatives are envisaged. These alternatives include the packing of articles other than kiwifruit such as eggs, or packing articles into receptacles other than boxes such as bags or tins. Throughout the body of the present specification, reference to the term "chassis" should be understood as meaning a frame forming the basic structure of the pick and place unit.

Preferably, the shape and configuration of the chassis may be variable depending on the application in which the pick and place unit is used.

Therefore, the foregoing should not be seen as limiting and alternatives are envisaged as long as these facilitate the use of the pick and place unit in article packing applications.

Throughout the body of the present specification reference to the term "head assembly" should be understood as meaning a component of the present invention having a plurality of work articles.

In a preferred embodiment, a head assembly may be configured to move between a pick up position and a packing position

Throughout the body of the present specification reference to the term pick up position should be understood as meaning a position in which the head assembly can engage an article to be placed into a receptacle.

Throughout the body of the present specification reference to the term "packing position" should be understood as meaning a position in which the head assembly can place an article in a receptacle.

In a particularly preferred embodiment the movement of a head assembly between the pick up position and packing position is in a linear manner relative to the chassis. Having a head assembly move in a linear manner relative to the chassis is advantageous as it means that the pick and place unit is more compact than other systems with head assemblies moving in a rotational manner.

However, there should not be seen as limiting and alternative embodiments are envisaged including an embodiment where the head assemblies are configured to move in a rotational manner with respect to the chassis.

Preferably, the head assemblies can move the work articles substantially vertically in both the pick up and packing positions. This aspect of the present invention will become apparent from the ensuing description.

However, the foregoing should not be seen as limiting and alternatives are envisaged including those which do not involve moving the work articles towards the objects or the receptacles.

In a preferred embodiment the present invention may have a plurality of conveyors.

In a particularly preferred embodiment, the present invention may have at least one object conveyor and a tray conveyor.

Throughout the body of the present specification reference to the term article conveyor should be understood as meaning a conveyor configured to present articles to the pick and place unit in a manner such that they can be placed into receptacles.

Throughout the body of the present specification reference to the term- tray conveyor should be understood as meaning a conveyor configured to transfer receptacles to the unit such that the pick and place unit is able to pack articles into the receptacle. In a particularly preferred embodiment the object conveyor may be a singulator as known to those skilled in the art.

Use of a singulator is advantageous as it is capable of transferring objects to the pick and place unit in an orderly arrangement from which they can be placed into a receptacle.

However, the foregoing should not be seen as limiting and alternative embodiments are envisaged. These include the use of two tray conveyors and one singulator or any combination of tray conveyors and other assemblies to transfer objections to the pick and place unit.

In a preferred embodiment, the work articles used with the pick and place unit according to the present invention may be suction pick-up heads as discussed above with reference to the movement assembly according to the second aspect of the present invention.

However, this should not been seen as limiting and alternative embodiments are envisaged including clamping pick-up heads.

In a preferred embodiment, the pick and place unit according to the third aspect of the present invention may utilise the movement assembly according to the first aspect of the present invention.

However, this should not be seen as limiting and alternative embodiments for the movement assembly are envisaged. These include telescoping ram driven assemblies or driven scissor assemblies.

The preferred embodiment of this aspect of the present invention provides a number of advantages. Firstly, a number a head assemblies can easily operate in combination with each other. For instance, one head assembly first picks up an object from a first conveyor and subsequently places this in a receptacle. While the object is being placed in the receptacle, the second head assembly can pick up an object from a second conveyor which it then places in the same receptacle. The head assemblies are therefore complimentary. This makes the packing process quicker and reduces the time which the machine needs to operate. Further, increases the number of articles which can be packed.

In addition, the pick up unit according to the present invention is less prone to wear and tear and can operate for longer periods of time without needing to be serviced or maintained. This again improves the productivity achieved using this invention over those available in the prior art.

In the embodiment where the movement assembly is that according to the second aspect of the present invention, the pick and place unit is more compact and its reliability is improved. Further the unit is cheaper to manufacture requiring less moving parts.

Further aspects of the present invention will become apparent from the ensuing description.

BRIEF DESCRIPTION OF DRAWINGS

Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which:

Figure 1a is a perspective view of Example 1 ;

Figure 1 b is an end view of the present invention as described in Example 1 ;

Figure 2 is a perspective view from the top of the head assemblies described in Example 1 ; Figure 2b is a perspective view from the bottom of the head assemblies described in Example 1 ;

Figure 3a is a perspective view of an X shaft;

Figure 3b is a side view of a pick up head secured to an X shaft;

Figure 3c is a cross section through line A-A of Figure 3b;

Figure 3d is an enlarged view taken from Figure 3c;

Figure 4a is a front elevation view of an X shaft in a retracted position from Example 2;

Figure 4b is a front elevation of an X shaft in an expanded position from Example 2;

Figure 5a is a front elevation of an X shaft in a retracted position from Example 3;

Figure 5b is a front elevation of an X shaft in an expanded position from ^■ Example 3;

Figure 6a is a front elevation view of an X shaft in a retracted position from Example 4; and

Figure 6b is a front elevation of an X shaft in an expanded position from Example 4.

BEST MODES FOR CARRYING OUT THE INVENTION

The present invention relates to a method and apparatus for controlling the relevant spacing of work articles along a row. In addition, another aspect of the present invention relates to a pick and place unit for use in article packing applications.

One significant application of the above inventions is in the use of packing fruit such as kiwifruit into boxes. In this embodiment, the fruit is presented in a uniform array using devices such as singulators known to those skilled in the art.

However, it is necessary to move the fruit from the XY arrangement in which it is presented, into an arrangement with differing spaces between and along the row of fruit. The ensuring descriptions are all provided with reference to this application.

However, it should be appreciated that the present inventions are equally applicable in other situations, for packing articles other than kiwifruit, or in controlling the relative positioning of other work articles such as liquid dispensers.

Example 1

Referring to Figures 1 through to 3c a first example can be seen. In Figures 1a and 1 b, a pick and place unit 5 is seen in combination with a fruit conveyor 6 and tray conveyors 7 and 8 to form a collating and packing system. It can be seen here that the fruit conveyor 6 and tray conveyors 7 and 8 are parallel one another and run parallel to axis marked "Y". The fruit conveyor 6 and tray conveyors 7 and 8 can be aligned in any way but it is advantageous if they are proximate one another so that picking and placing of the items from the conveyor 6 onto the trays on the tray conveyors 7 and 8 is made easier. ■ ■•

It will be seen here that the pick and place unit 5 is located such that it can most effectively access items from above both the tray conveyor 6 and place them in containers on the tray conveyors 7 and 8.

The pick and place unit 5 includes a chassis 9 and a linear guide track assembly 9a. Preferably the linear guide track assembly 9a is formed from linear tracks and a body 16 slidably mounted on the linear tracks. The body 16 of the linear track assembly is attached to head assemblies 10 and 11. Accordingly the result is that heads 10 and 11 are capable of movement relative to the chassis 9.

The linear guide track assembly 9a is actuated to move each of the head assemblies 10 and 11 into alternating contact with the kiwifruit on the fruit. conveyor . 6 and then the trays on the tray conveyors 7 and 8. Two head assemblies are used here as it enables one of the head assemblies to be picking fruit from the fruit conveyor 6 while the other is placing the fruit into the trays on the tray conveyors. Accordingly, the head assemblies will be moved along both the X and Z directions indicated on Figure 1. Movement of the head assemblies in the Z direction in this example is by way of a servo motor 17 (seen in Figure 1b) and movement in the X direction is caused by a linear actuator (not shown).

It will be appreciated by persons skilled in the art that more head assemblies and more fruit conveyors 6 and/or tray conveyors 7 and 8 may be used to increase the rate of processing.

The fruit conveyor 6 is in the form of a singulator which is commonly used in kiwifruit pack houses to collate fruit.

The trays in the tray conveyors will contain inserts containing pockets to receive fruit. The layout of pockets in a tray is referred to as the "count" by those skilled in the art.- Most singulators deliver kiwifruit in rows of six. A standard count is a 36 count which is typically provided in the form of 6 rows of 6. Accordingly many existing pick and place units will only be designed to place 36 kiwifruit into each insert of a tray.

However, here it is possible to accommodate inserts having a variable range of pocket sizes and numbers to provide a smaller or larger count than the standard

36 count delivered by the singulator. However, this example is most likely to be used to provide a 33 or 36 count as they are the most commonly required in the kiwifruit industry.

The head assemblies 10 and 11 can best be seen with reference to figures 2a & 2b. It can be seen here that each head assembly has a plurality of pick up heads 12 organised into rows. Preferably the rows form an X-Y pattern but other patterns may be utilised. The work articles heads are all mounted on drive axles 21 which are shown in Figures 3a and 3b. These drive shafts are substantially aligned with the X-axis (hereinafter referred to as "X 13(a/b)").

The rows are interconnected by a drive axle running substantially perpendicular to the X-axles. The axles interconnecting the rows are hereinafter referred to as "Y axles" 14. The X axles 13 a & b) in this example are also coupled with guide assemblies.

Referring to Figure 2a it can be seen here that head assembly 10 is shown in the expanded position which would generally occur when the fruit is being picked from the fruit conveyor 6 and head assembly 11 is shown in the retracted position which would generally occur when the fruit is being placed into a tray.

Also visible from Figures 2a and 2b is that the rows of work articles on head 11 are offset from one another which corresponds with the offset pockets in the plix trays. This feature can be provided by every second X axle being provided with an offset function. However, in this example every X axle is adapted to perform this offset function so that a wider variety of tray shapes and sizes can be accommodated. Accordingly there are two types of X axles; 13a and 13b which alternate with one another in the X-Y pattern. X axles 13a are adapted to be offset a different amount to different positions to that of X axles 13b.

An X axle can be best seen in Figures 3a/b/c. Referring to Figures 3a to 3c it can be seen that the X-axle have a plurality of pick up heads 12 mounted along the drive shaft 21 and coupled to the linear guide 20. Each X axle is actuated by a stepper motor 26. Actuator 29 which provides the offset function can also be seen here. It will be appreciated that the location of the stepper motor 26 and actuator 29 on X axle 13a may differ slightly from the location of the stepper motor 26 and actuator 29 on X axle 13b merely to enable the rows to be arranged closely together on each head.

Each work article 12 contains means for engaging with the fruit. In this example vacuum cups 23 are used to minimise damage to the fruit. These will be referred to as pick up heads herein. It will be noted that, in this example, the number of pick up heads on each head assembly is 36 which corresponds with the use of a singulator used in the industry which delivers 6 kiwifruit in each row.

Accordingly, the pick up heads 12 in this example are linked such that controlled movement of one pick up head on an X axle 13 will successively cause controlled movement of other pick up heads on that axle. From figure 3c it will be apparent that movement of the pick. up heads 12 relative one another on the axles 13a & B is achieved, in this example, by way of the movement assembly. The drive axles 21 will have a threaded drive portion 22 operatively associated with the drive axle around at least a portion of their outer circumference and the pick up heads 12 have corresponding thread forms 18.

One end of each threaded engagement portion 22 is coupled with a first pick up head and is rotatable relative to the pick up head via bearing 24 and the other end of the thread form 22 is in threaded engagement with the corresponding thread form 18 in the second adjacent pick up head. Each pair of adjacent pick up heads is connected in a similar manner, along the length of the shaft. The first of the pick up heads in a row may be anchored to form a reference point. It will be apparent to those skilled in the art that the result of this arrangement is that by actuating the drive shaft 21 rotational movement of the drive . shaft will translate into linear motion of the pick up heads and that due to the link between the pick up heads, movement of one pick up head along the length of the drive shaft results in movement of the other pick up heads in that row.

Movement of the pick up heads on the shafts is actuated by an electronically controlled actuator adapted to be controlled by an electronic control device. The actuator here is in the form of a stepper motor and the electronic control device will be a suitable microprocessor. It was determined that by using this type of actuator, not only precise controlled movement is provided but also variable degrees of settings for a fully retracted position whereby the pick up heads are spaced as far apart along the shaft as allowable and a fully actuated position whereby the pick up heads are as closely positioned as allowable. The electronic control device controls movement of the heads.

In this example each axle, is individually controlled by a separate stepper motor which allows for more variation/adjustment to be achieved

In use the user will ascertain the grade or size of the fruit. This variable will dictate which insert in the tray will be used. The pick and place machine must then be adjusted to be able to pick the fruit from the singulator whereby the fruit will be presented at one particular spacing and is then able to place the fruit in the pockets of the insert at a different spacing.

This adjustment is easy to do and can be done between runs of different grades of fruit.

Once these variables are selected the stepper motors will adjust the movement accordingly. For a 22 count you could have five rows of 4, 5, 4, 5, 4 heads per row.

For a 27 count you could have five rows of 5, 6, 5, 6, 5 heads per row.

For a 36 count 6 rows of six kiwifruit would be a suitable arrangement.

For a 30 count 5 rows of six kiwifruit or six rows of five kiwifruit per rowcould be ^• used. For a 33 count there could be 6 rows an alternating number of kiwifruit: 5, 6, and 5, 6, 5, 6.

However, as discussed previously, the most likely counts used in the kiwifruit industry will be 33 or most commonly a 36 count.

Example 2

In this example, the invention will be described with reference to Figures 4a and 4b.- In this example the controlled linked movement of the pick up heads relative to one another on each X axle is achieved by way of a combination of variable pitch lead threads which provide controlled movement of the pick up heads along the drive shaft. In such a case, the lead threads have different thread pitches and different thread directions so each pick up head will travel a different distance and/or direction to another. In this example the combination of lead threads are as follows 10mm left hand thread 31 , 6mm left hand thread 32, 2mm left hand thread 33, 2mm right hand thread 34, 6mm right hand thread 35 and 10mm right hand thread 36.

Preferably the datum 30 the pick up heads move towards and away from is substantially around the middle section of the drive shaft.

Here, the pick up heads move away from the datum towards the end region of the drive shaft to spread out when the expanded position is required. Conversely, the pick up heads move towards the datum from the end region of the drive shaft to come closer together when the retracted position is required.

The retracted position is seen in Figure 4a. When the drive shaft 21 is revolved the pick up heads 12 will move apart and keep the same distance between all centres refer distance "d1". In this example d1 may be around 54mm.

One turn of the drive shaft results in lead threads 33 and 34 moving 2mm, lead threads 32 and 35 moving 6mm and lead threads 31 and 36 moving 10mm.

In this example in the expanded position seen in Figure 5b the distance between centres "d2" may be around 76mm.

To allow assembly, the different lead threads may be different diameters (larger in the centre) or the threaded blocks 37 may be split.

Example 3

In this example, the invention will be described with reference to Figures 5a and 5b. In this example, the controlled linked linear movement of the pick up heads 12 relative to one another on each X axle is achieved by way of mounting the pick up heads to linear tracks 40 and linking each pick up head 12 together using a chain of scissor links 41 which are capable of extending and retracting to allow for linear movement of the pick up heads.

Here, one end of the chain 41 is attached to or connected with a linear motor or linear ball screw actuator. The other end of the chain 41 is attached to a fixed body 42 incapable of linear movement along the linear guide shafts. Most preferably this body will be a pick up head that is fixed into position on the linear shaft.

Example 4 This example is best seen with reference to Figures 6a and 6b. In this example it can be seen that this example consists of a series of linear electric motors 50 slidably mounted on a linear motor slider 51 each of which individually powers a pick up head 12 fixed thereto.

Movement of the pick up heads is guided along a linear guide shaft 20. When the linear motors 50 are actuated they move along the slider 51 via an electronic "absolute encoder" which can be programmed for any distance position.. The pick up units 12 will move apart and keep the same distance between centres.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

Claims

WHAT I/WE CLAIM IS:

1. A method of controlling the spacing of work articles along a row, including the steps of

positioning a drive axle with respect to the row,

positioning two or more work articles such that they are substantially aligned with the longitudinal axis of the axle,

wherein at least one work article has a complimentary thread engaged with an associated drive portion,

characterised by the step of,

2. The method as claimed in claim one, wherein the drive axle rotates to a predetermined position.

3. The method as claimed in either claims 1 or 2, wherein the drive axle is rotated by a stepper motor.

4. The method as claimed in any one of claims 1 to 3, wherein the work article is a pick up head.

5. The method as claimed in claim 4, wherein the pick up head is a suction pick up head.

6. The method as claimed in any one of claims 1 to 5, wherein at least one threaded drive portion is coupled to a work article.

7. The method as claimed in claim 6, wherein the coupling is configured to allow the threaded drive portion to rotate relative to the work article.

8. The method as claimed in claim 10, wherein the threaded drive portion engages a complementary thread connected to a second work article.

9. The method as claimed in any one of claims 1 to 8, wherein the method is used to control the spacing of work articles within a two dimensional array.

10. The method as claimed in any one of claims 1 to 8, wherein the method is used to control the spacing of work articles within a three dimensional array.

11. A movement assembly, including:

a drive axle,

a number of threaded drive portions operatively associated with the axle,

two or more work articles positioned in a row substantially aligned with the longitudinal axis of the drive axle,

at least one work article having a complimentary thread engaged with an associated drive portion,

characterised in that

the movement assembly is configured such that rotation of the drive axle causes the threaded drive portions to turn and alter the spacing between the engaged work articles along the row.

12. The movement assembly as claimed in claim 11 , wherein the drive axle rotates to a predetermined position.

13. The movement assembly as claimed in either one of claims 11 or 12, wherein the rotation of the drive axle is controlled by a stepper motor.

14. The movement assembly as claimed in any one of claims 11 to 13, wherein the pitch or length of the threaded drive portions is variable.

15. The movement assembly as claimed in any one of claims 11 to 14, wherein the threaded drive portions have threads with different pitch or length.

16. The movement assembly as claimed in any one of claims 11 to 15, wherein the threaded drive portions are configured to move along the longitudinal axis of the drive axle.

17. The movement assembly as claimed in any one of claims 11 to 16, wherein at least one threaded drive portion is coupled to a work article.

18. The movement assembly as claimed in claim 17, wherein the coupling allows the threaded drive portion to rotate relative to the work article.

19. The movement assembly as claimed in either one of claims 17 or 18, wherein the threaded drive portion engages the complimentary thread of a second work article.

20. A movement assembly as claimed in any one of claims 11 to 19, wherein the movement assembly includes a guide assembly.

21. A movement assembly as claimed in any one of claims 11 to 20, wherein the movement assembly is used to control the spacing of work articles within a two dimensional array.

22. The movement assembly as claimed in any one of claims 11 to 20, wherein the movement assembly is used to control the spacing of work articles within. a three dimensional array.

23. A pick and place unit, characterised as having

a chassis,

at least two head assemblies configured to move relative to the chassis,

each head assembly having a row of work articles,

a movement assembly configured to control the spacing of the work articles.

24. A pick and place unit as claimed in claim 23, wherein the head assemblies are configured to move between a pick up position and a packing position.

25. The unit as claimed in claim 26 wherein the movement between the pick up position and packing position is linear movement.

26. The unit as claimed in any one of claims 23 to 25, wherein the head assembly is configured to move the work articles in a substantially vertical manner.

27. The unit as claimed in any one of claims 23 to 26, wherein the unit has a plurality of conveyors.

28. The pick and place unit as claimed in claim 27, wherein the plurality of conveyors are an article conveyor and a tray conveyor.

29. The unit as claimed in claim 28, wherein the article conveyor is a singlulator.

30. The unit as claimed in any one of claims 23 to 29, wherein the movement assembly is a movement assembly according to any one of claims 11 to 22.

31. A pick and place unit as substantially described herein with reference to the attached drawings and description.

32. A method of controlling the spacing of work articles along a row as substantially described herein with reference to the attached drawings and description.

33. A movement assembly as substantially described herein with reference to the attached drawings and description.