GB2437412A

GB2437412A - Position and angle sensing in a welded plastic cleaning machine

Info

Publication number: GB2437412A
Application number: GB0707605A
Authority: GB
Inventors: Michael John Ritchie; David Parsons
Original assignee: GTI KOMBIMATEC MACHINES Ltd; KOMBIMATEC MACHINES Ltd
Current assignee: GTI KOMBIMATEC MACHINES Ltd; KOMBIMATEC MACHINES Ltd
Priority date: 2006-04-21
Filing date: 2007-04-19
Publication date: 2007-10-24
Also published as: GB0607833D0; GB0707605D0

Abstract

An apparatus and method are provided for comparing a position of a joint in a cleaning machine with an ideal position, such that the position of the joint can be adjusted if required. In preferred embodiments a welded joint 16 in a PVC window frame 12 is deburred by a cleaning machine comprising two sensors, the first sensor determining the position of the join and the second sensor 22 determining the angle of the joint from which welding beads should be removed. The second sensor may comprise a pin 20 that is pushed into the inside of the joint so that, from the position at which the pin is stopped by the joint, the angle of the joint is determined. A processing means may calculate a modified optimal position for the joint taking into account the relative angle of the joint. In this way, the machine can accept window frames with joining angles other than 90 degrees. Fences 14 guide the frame and may be adjustable over a range of angles.

Description

POSITION SENSING APPARATUS

This invention relates to apparatus for sensing whether a joint is in a predefined position.

The invention is applicable to use within machines that clean excess plastic from welded joints in UPVC frames.

During the process of welding frame joints in extruded PVC window and door profiles, a flash or sprue is developed and this requires cleaning off. Machines have been used to clean the flash from the PVC frame. However, these machines require the frame to be correctly positioned on loading into the machine. This is in order that the joint is correctly aligned with the cutting tools in order that optimal cleaning occurs. The correct positioning of the joint occurs when the joint is located on the centre line of the cutting machine and the length of the joint is aligned parallel with the centre line of the cutting machine.

Traditionally, frames are loaded onto a machine and located against fences which project from the surface of a table part of the cleaning machine. However, often a frame's joints are not the desired angle, for example 900, resulting in the fences not accurately aligning the joint with the cutting tools even when frame is correctly inserted.

Therefore, a way of improving the way that frames are aligned when placed into the cleaning frame is required.

According to a first aspect of the invention there is provided Apparatus for measuring the position of a joint between two members in a cleaning machine, the apparatus comprising a first sensor adapted to detect the position of the joint within the machine and a first

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processing means adapted to compare the position of the joint relative to the optimal position for the joint such that the position of the joint can be altered until the joint is in the optimal position.

Preferably, the apparatus includes a pin adapted to fit into the inside of the joint a second sensor connected to the pin and adapted to detect the position of the pin in relation to a specified position and a second processing means adapted to compare the position of the pin to the specified position to determine the angle between the two members such that the second processing means having determined the angle of the joint recalculates the optimal position of the joint.

Preferably, the second sensor is connected to the pin by a pneumatic cylinder, hydraulic cylinder or spring.

The optimal position of the joint may be determined using a table relating the angle of the joint to the optimal position of the joint or alternatively using an equation that relates the angle of the joint to the optimal position of the joint The apparatus may include two or more fences, the fences adapted to be either side of one or both of the members and configured such that the joint can be held in a desired position.

Preferably, the fences are actuated by a pneumatic cylinder, a hydraulic cylinder, or electrical motor and can rotate about a point such that they can accommodate joints of different angles.

Preferably, if the joint is not in the optimal position there is output to a user interface so that a user is able to manually manipulate the joint until they are in the optimal position.

In accordance with a second aspect of the present invention there is provided a method of determining the position of a joint between two members in a cleaning machine, the method comprising the steps of: detecting the position of the joint and comparing the position of the joint relative to the optimal position for the joint such that the position of the joint can be altered until the joint is in the optimal position.

Preferably, the method further includes the steps of detecting the position of a pin in relation to a specified position, the pin being placed on the inside of the joint and comparing the position of the pin to the specified position to determine the angle between the two members.

According to a second aspect of the present invention there is provided a method of determining the position of a joint between two members in a cleaning machine, the method comprising the steps of detecting the position of the joint and comparing the position of the joint relative to the optimal position for the joint such that the position of the joint can be altered until the joint is in the optimal position.

Figure 1 is a plan view of a cleaning machine; Figure 2 is an enlarged view of the positioning apparatus; Figure 3a is a further plan view of apparatus to determine the angle of a joint; Figure 3b is a further plan view of apparatus to determine the angle of a joint when the angle of the joint is 87 ; Figure 3c is a further plan view of apparatus to determine the angle of a joint when the angle of the joint is 93 ; and Figure 4 illustrates a method for aligning a joint in a cleaning machine.

With reference to Figure 1, a cleaning machine 10 is provided with a table 11 onto which a frame 12 to be cleaned may be placed by a user 13. The table 11 is shown in more detail in Figure 2 and is provided with a number of projections 14, referred to as fences. There are preferably four fences 14, two on the outside of the frame 12 and two on the inside of the frame 12 along the sides of the frame 12 adjacent to the joint 16 to be cleaned.

The fences 14 are able to rotate in order to accommodate frames 12 with joints 16 of angles that are not the desired angle, such as 90 . Preferably, the fences 14 are able to rotate sufficiently to enable a frame 12 with a joint 16 with an angle deviating a specified amount from the desired angle, for example the fences may accommodate joints 3 from the optimum angle. The fences 14 are further adapted to be locked in position such that when the joint 16 is in the desired position it is held firmly in that position to ensure optimal cleaning of the joint 16. The fences may be locked in position by any suitable means, for example, an electrical motor or by a pneumatic or hydraulic cylinder.

The cleaning machine is provided with one or more cutting tools (not shown) which are fixed to a moveable tool carrier (not shown). In a default configuration the cutting tools are positioned such that they are in the correct position to optimally clean a joint having the desired angle.

The first sensors 18 may be configured to measure the alignment of the tool carrier relative to the actual tool centre line in both a perpendicular and a parallel direction. Alternatively, the first sensors 18 may be configured to measure the alignment of the tool carrier with reference to the frame's alignment directly. The measurement of the carrier alignment will be discussed below with reference to a pneumatic cylinder; however, it will be readily understandable that any other suitable sensing means may be used. Examples of suitable sensing means are: lasers,, imaging sensors, photoelectric sensors and capacitive or inductive sensors.

The sensor(s) 18 is provided with a cylindrical rod that will contact the tool carrier, the cylindrical rod being retractable into and extendable from the body of the pneumatic cylinder.

The sensor records the extent of displacement of the cylindrical rod, and therefore the position of the tool carrier by any suitable means. The sensor(s) 18 then transmits the recorded alignment of the tool carrier to a first processing means 18 that compares the actual position of the tool carrier to the optimal position of the tool carrier in relation to the joint 16. As stated above, the optimal position of the tool carrier in relation to the joint 16 is when the tool carrier is in the correct position to optimally clean a joint having the desired angle.

The first processing means (not shown) may then transmit the difference between the actual position of the joint 16 and the optimal position of the joint, or any other suitable information such as how the joint should be repositioned with reference to the frame 12, to a user interface so that the user 13 can then manually adjust the position of the joint.

The cleaning machine is also provided with a locating pin 20 which is preferably retractable such that the frame can be inserted into the position shown in Figure 2.The locating pin 20 is connectable to a second processing means (not shown).

Preferably, the locating pin 20 is moveably connectable to a device 22 such that the distance between the locating pin 20 and the device 22 alters according to the position of the locating pin 20. Even more preferably the device 22 is a pneumatic cylinder with the locating pin 20 connected, for example, to a cylindrical rod which is retractable into and extendable from the body of the pneumatic cylinder. The device may also be a hydraulic cylinder, a spring or any other suitable means. The device is provided with a sensor (not shown) for measuring the extent of displacement of the locating pin 20 relative to that the rod extends into the cylinder by any suitable means.

Once the sensor has measured the displacement of the locating pin 20 the displacement of the locating pin is transmitted to a second processing means which may or may not be integral with the device 22. The second processing means then calculates the angle of the joint according to the amount of displacement of the locating pin 20 as shown in Figures 3a to 3c.

Preferably a neutral distance is defined as the distance between the locating pin 20 and a point on the device 22 or some other predetermined point, as shown in Figure 3a. When the distance between the locating pin 20 and the point is X, the second processing means is configured to determine that the angle of the joint 16 is desired angle. Preferably the first processing means is configured such that the default position of the cutting tools is the optimal position for cleaning a joint with the desired angle. Hence when the angle of the joint is the desired angle no recalculation of the optimal position is required and cleaning of the joint can commence.

The joint shown in Figure 3b has an angle that is less than the desired angle, in this instance 87 . This means that the pin contacts the two sides of the frame 12 that meet at joint 16 at a distance greater than X, for example, X-n. The sensor detects the displacement of X+n and transmits this distance to the second processing means which converts the distance of X-n to the angle of the joint, i.e. 87 .

The second processing means may be provided memory in which is stored a table that links the amount of displacement of the locating pin from the distance X or another predefined point directly to the corresponding joint angle. This would mean that, for example, a displacement from X of n is related in the table to the angle of the joint 16 being 30 smaller than the desired angle of 90 . Alternatively, the processing means may use an equation to calculate the joint angle from the displacement of the locating pin. The second processing means may calculate the angle of the joint using any other suitable means.

In Figure 3c, the angle of the joint is greater than the desired angle, for example 93 .

Therefore, the locating pin will contact the two sides that meet at the joint 16 at a distance that is greater than X. The processing means then converts this distance to the angle of the joint using any of the methods discussed above.

Once the second processing means has calculated the angle of the joint it transmits this value to the first processing means. The first processing means then recalculates the optimal position of the joint according to the angle of the joint detected by the second sensor and processing means. This may be done by the first processing means consulting a table that links the angle of the joint directly to the optimal position of the joint. Alternatively, the processing means may use an equation to calculate the optimal position of the joint from the angle of the joint. Any other suitable means may be used to calculate the amended optimal position of the joint.

Optionally, the second processing means or a third processing means may calculate the optimal alignment of the joint for the angle of the joint and transmit the optimal alignment of the joint to the first processing means.

A method for using the machine will now be described with reference to Figure 4. When a user wishes to clean a joint in a frame, the joint being where two sides of the frame meet, the user first places the frame onto the table with the joint aligned with the cutting tools of the machine as shown in Step 26. The frame is placed with the inside corner of the joint in contact with the locating pin and the two sides positioned between the fences as illustrated in Figures 1 and 2. Once the frame has been piaced onto the table in the correct position the fences will become fixed in position as shown in Step 28.

The fences becoming fixed in position causes the sensor connected to the first processing means to be activated. The sensor then measures the alignment of the tool carrier and transmits the alignment to the first processing means as shown in Steps 30 and 32 respectively. The first processing means then determines whether the tool carrier is optimally positioned as shown in Step 34 and, if the joint is not in the default optimal position, then causes the joint to be manoeuvred until it is in the optimal position using any of the methods described with reference to Figure 2 as shown in Step 36. The optimal position of the joint advantageously occurs when the frame is aUgned so that the frame is central to and parallel with the tool centre line.

Once the joint is in the optimal position the fences become fixed in position in order to hold the members in the position that will result in optimal cleaning of the joint. The second sensor is then activated and measures the displacement of the locating pin as described above and shown in Step 38. The sensor then transmits the displacement of the locating pin to the second processing means. From the displacement of the locating pin the second processing means determines the position which the tooling should be in to clean the joint (step 42). The tooling is then moved to this position; the positioning procedure is completed (step 44) and cleaning can commence.

Rather than moving the tooling to the optimum position as described above with reference to Steps 38 to 44 in alternative embodiment the orientation of the joint is adjusted. In this embodiment the location of the joint is determined as described above and, once the fences are fixed the second sensor transmits a signal indicating the displacement of a locating pin to second processing means. The second processing means, in response to the signal from the second sensor, recalculates the optimal position of the frame. The recalculated optimal position is then compared to the original optimal position in step 36 and, if the optimal position is unchanged, the positioning process is completed and cleaning can proceed.

However, if the optimal alignment has altered then the position of the frame is altered and the process recommences at step 30 as described previously with reference to the earlier embodiment until the optimal alignment remains unchanged.

Alternatively, the cleaning may begin after the frame has been manoeuvred into the recalculated optimal position.

In both of the embodiments described above the second sensor may measure the angle of the joint rather than displacement of a locating pin to which the sensor is attached. In this instance the second sensor then transmits the angle measurement to the second processing means and the second processor uses the angle of the joint to calculate the position of the tooling or recalculate the optimal position of the frame.

Alternatively, the second processor may, on receiving a signal transmitting a displacement, calculate the angle of the joint. The angle of the joint can then be used to calculate the position of the tooling or recalculate the optimal position of the frame.

The sensing apparatus described herein may be configured such that it can measure the optimal position of an object in one or more planes.

Claims

CLAIMS

1. Apparatus for measuring the position of a joint between two members in a cleaning machine, the apparatus comprising: (i) a first sensor adapted to detect the position of the joint within the machine; and (ii) a first processing means adapted to compare the position of the joint relative to the optimal position for the joint; such that the position of the joint can be altered until the joint is in the optimal position.

2. Apparatus as claimed in Claim 1 further comprising: (iii) a pin adapted to fit into the inside of the joint (iv) a second sensor connected to the pin and adapted to detect the position of the pin in relation to a specified position; and (v) a second processing means adapted to compare the position of the pin to the specified position to determine the angle between the two members such that the second processing means having determined the angle of the joint recalculates the optimal position of the joint.

3. Apparatus according to Claim 2 wherein the second sensor is connected to the pin by a pneumatic cylinder, hydraulic cylinder or spring.

4. Apparatus according to claims 2 wherein the optimal position of the joint is determined using a table relating the angle of the joint to the optimal position of the joint.

5. Apparatus according to claims 2 wherein the optimal position of the joint is determined using an equation that relates the angle of the joint to the optimal position of the joint.

6. Apparatus according to any preceding claim wherein the apparatus further comprises two or more fences, the fences adapted to be either side of one or both of the members and configured such that the joint can be held in a desired position.

7. Apparatus according to Claim 6 wherein the fences are actuated by a pneumatic cylinder, a hydraulic cylinder, or electrical motor.

8. Apparatus according to Claim 6 or Claim 7 wherein the fences can rotate about a point such that they can accommodate joints of different angles.

9. Apparatus according to any preceding claim wherein if the joint not in the optimal position this is output to a user interface so that a user is able to manually manipulate the joint is in the optimal position.

10. Apparatus according to any preceding claim wherein the cutting tools are connected to a plate and, if the cutting tools are not in the optimal position, the plate adjusts its position until the cutting tools are in the optimal position. /

ii. A method of determining the position of a joint between two members in a cleaning machine, the method comprising the steps of: (i) detecting the position of the joint; and (ii) comparing the position of the joint relative to the optimal position for the joint; such that the position of the joint can be altered until the joint is in the optimal position.

12. The method as claimed in Claim 12 further comprising the steps of: (iii) detecting the position of a pin in relation to a specified position, the pin being placed on the inside of the joint; and (iv) comparing the position of the pin to the specified position to determine the angle between the two members.

13. Apparatus substantially as herein described with reference to and as shown in any combination of the accompanying drawings.

14. A method substantially as herein described with reference to and as shown in any combination of the accompanying drawings.