Paint mixing apparatus

Abstract

 A paint mixing apparatus comprises input means (14) for inputting a desired paint composition and formulation means (12) for formulating the desired paint composition from a set of paint components. Further input means (14) are provided for inputting a limiting value of a paint property and control means (10) monitoring a cumulative value of the paint property for the paint components used by the formulation means (12) in order to suspend operation of the formulation means (12) if the cumulative value of the paint property exceeds the limiting value. The paint property for which a limiting value is input may be, among other things, the cost of the paint or the solvent content of the paint to allow improved control of costs or environmental pollution.

Description

Technical field

[0001] The invention relates to apparatus for mixing formulations of paint or other materials and for calculating their cost and content of pollutants. It has particular application in circumstances where successive mixtures are required to have different volumes and compositions, for example in vehicle repair body shops.

Background of the invention

[0002] Paint weighing machines are well known, which include a weighing device, a computer and a memory for storing details of formulations of a large number of paint components. An operator enters details such as colour, quality and volume of paint required for a particular paint job and the computer of the weighing machine calculates a suitable formulation from the paint components available. The operator is instructed to add appropriate amounts of the paint components, measured using the weighing device, in order to create the desired formulation. In some weighing machines, the addition of too much of one paint component by the operator can be compensated by revising the formulation. An example of this type of weighing machine is MIXIT, sold by Akzo Coatings plc.

[0003] Although the weighing machine controls the formulation of the paint mixed by the operator, it is left to the judgement of the operator to mix a suitable quantity of paint for the job that needs to be done. Naturally, it is desirable to use the minimum amount of paint in order to reduce the cost of the job, to avoid waste and to minimize air pollution by volatile organic compounds (VOC). However, the operator is likely to overestimate the amount of paint needed rather than risk having to mix a second batch and there is generally no system for recording whether the amount of paint mixed is appropriate.

[0004] In many contexts, the paint job may be subject to an overall cost limitation. This is particularly true in the context of a vehicle repair body shop, where estimated costs for the vehicle repair and for the various jobs involved in the repair have typically been agreed between an insurance assessor and the managers of the body shop. It would be desirable to constrain the cost of the paint to keep within the estimate. It would also be desirable to record the cost of the paint in order to compare it with the estimated value. That might allow future estimates to be improved or it might allow particularly efficient operators to be identified.

[0005] A further constraint on the paint used in a paint job is an environmental one. Paints and similar materials contain solvents and other volatile organic compounds that can degrade the environment. Increasingly, the use and emission of such pollutants is being regulated. Vehicle body shops are required to account for the quantities that they use and may be fined if the quantities are excessive, in accordance with the policy of "polluter pays". The environmental agencies also need a technique for implementing the principle of using the "best available technique not exceeding excessive cost". Thus it would be desirable to record the amounts of solvents in the paints mixed by the weighing machine in each individual job and to constrain the total not to exceed a prescribed limit. At present, monitoring of these figures done retrospectively in relation to the materials purchased, not the materials used.

Summary of the invention

[0006] The invention provides paint mixing apparatus comprising: input means for inputting a desired paint composition; and formulation means for formulating the desired paint composition from a set of paint components; CHARACTERIZED BY input means for inputting a limiting value of a paint property; and control means for monitoring a cumulative value of the paint property for the paint components used by the formulation means and for suspending operation of the formulation means if the cumulative value of the paint property exceeds the limiting value.

[0007] The paint property for which a limiting value is input may be, among other things, the cost of the paint or the content of volatile organic compounds in the paint.

[0008] The invention thus allows the physical control of the weighing machine, dependent on a limiting value of the paint property determined in advance. Thus the manager of the operation can ensure that a paint job remains within the limiting value in order to meet targets such as cost or pollution control and the manager does not have to rely on the good judgement of the weighing machine operator. Unlike the prior art, which could only react to the value of the paint property after the paint had been used, the present invention allows a paint property such as cost or pollutant emissions of each individual paint job to be quantitatively controlled in advance.

[0009] The paint mixing apparatus preferably further comprises override means, by which an operator can allow operation of the weighing machine to continue after operation has been suspended by the control means. In most cases, the fact that the weighing machine operator has exceeded the paint property limit will not mean that the job should be entirely abandoned; merely that the repair shop manager will need to be informed and to give approval for the job to continue. Thus there is an opportunity to investigate and perhaps to correct the reason for exceeding the estimated value.

[0010] Preferably the paint mixing apparatus further includes means for recording the limiting value and the final cumulative value of the paint property. This allows the performance of both the estimator and the weighing machine operator to be assessed, as well as allowing for closer control over the usage of paint and compliance with environmental audit regulations.

[0011] The apparatus may further comprise a printer for printing a record after the paint has been mixed. Preferably the printer is also connected to the formulation means for printing a label for the paint that has been mixed. This allows the printer that is generally provided with commercially available weighing machines to be used additionally for the printing of a job record card or an entry on a job record card, which facilitates integration of the paint mixing apparatus of the present invention with an established paper-based job recording system.

[0012] Where the control means is a computer for managing vehicle repair jobs, the apparatus may further include input means for inputting a job reference to identify the repair job for which the paint is to be mixed. This further allows the task of paint mixing to be integrated with other tasks involved in the vehicle repair job using a common reference, and it avoids unnecessary duplication of data entry in connection with different tasks.

[0013] Although this specification generally refers to the composition being mixed as "paint", it should be understood that the invention includes apparatus for mixing similar materials such as varnish or lacquer and indeed any mixture in which the composition may be varied.

The Drawings

[0014] 

Figure 1 is a schematic diagram showing the relationship between the elements of paint mixing apparatus in accordance with a preferred embodiment of the invention.

Figure 2 is a flowchart illustrating operation of the control computer of Figure 1.

Figure 3 is a flowchart illustrating operation of the weighing machine of Figure 1.

[0015] The invention is described and illustrated in the drawings in the context of a paint mixing apparatus for use in a vehicle body repair shop, although it has other applications as previously discussed.

[0016] As shown in Figure 1, the paint mixing apparatus comprises a control computer 10 and a weighing machine 12. The control computer 10 preferably forms part of a general repair shop management system performing other tasks beside controlling the paint mixing apparatus. Some of those tasks are described below. The control computer 10 includes a memory (not shown) for storing records of different repair jobs, among other things. Connected to the control computer 10 are input means 14, such as a keyboard or a mouse, for receiving information from the user; a display 16 for presenting information to the user; a general printer 15 and a label printer 22.

[0017] Also connected to the control computer 10 is a weighing machine 12. The weighing machine 12 may contain a dedicated computer, with a memory (not shown) for storing details of the properties of a large number of paint components. Alternatively the weighing machine 12 may be controlled by the control computer 10. The connection between the control computer 10 and the weighing machine 12 may be direct or across a local network, as is well known. The weighing machine 12 will generally be a commercially available machine interfaced with the control computer 10 of the vehicle body repair shop but the invention could also be put into effect in an integrated system where the functions of the weighing machine computer 12 were carried out by the control computer 10.

[0018] The weighing machine 12 includes a display 18 for prompting the machine operator to add suitable proportions of the paint components in order to formulate a paint having the desired composition. The weighing machine 12 also includes a weighing device 20, upon which the paint is mixed, to allow feedback of the quantities of paint components added to the mixture by the operator. Preferably, the weighing machine 12 is able to adjust the formulation to accommodate errors in the amount of paint component added by the operator, while retaining the desired overall properties of the formulated paint.

[0019] Figure 2 illustrates a sequence of steps for operating the control computer 10 in Figure 1 to mix a set of paints for a desired paint structure, while keeping within a predetermined cost limit. In the first step 30, a user inputs to the control computer 10 a reference for the vehicle repair job in question. This reference is common to all tasks carried out as part of the vehicle repair job and allows the costs and organization of the entire job to be coordinated. For example, the make of vehicle will generally already be stored in the memory of the control computer 10 and can be retrieved using the job reference to avoid re-entering that data. Any necessary further details of the job can be input in step 31.

[0020] In the next step 32, the user inputs the paint structure for the paint job in question. The paint structure includes details of the vehicle component to be painted and both qualitative and quantitative details of all paints that will be needed to complete the paint job. The vehicle component may require several layers of different paints, such as primer, body coat, pearl coat and lacquer. At least some of these details may be obtainable from a database of vehicle component parts, accessed through the job reference, without being individually input again.

[0021] The next step 34 is for the user to input an upper limit for the cost of each paint to be used in the paint structure. These maximum limits will be determined in advance by the managers of the vehicle repair shop, typically after discussion of the overall cost of the paint job with an insurance assessor who will be responsible for paying for the repair. Where the cost per litre of each paint is known, the maximum costs can be converted immediately into maximum volumes for sending to the weighing machine 12. Alternatively, the conversion from cost to volume could be effected within the weighing machine 12. The weighing machine 12 in practice measures quantities of paint by weight using the weighing device 20, so the cost values may instead be converted directly to weight values. It will be understood that the unit in which the quantities are expressed is not essential to the performance of the invention.

[0022] In step 36, the user inputs an agreed time for the work spent on the paint job. Again, the agreed time will be determined by the managers of the vehicle repair shop after discussion with the insurance assessor. The agreed time corresponds to the amount the assessor is willing to pay for the labour involved in the paint job element of the vehicle repair. The user may optionally input a further time, the allowed time, which is a duration shorter than the agreed time. The operator carrying out the paint job will be encouraged to complete the job within the allowed time, which gives a margin of error if the job should over-run.

[0023] This completes the input of information relating to the paint job. Other information, relating to other aspects of the repair, may conveniently be input to the control computer 10 at the same time and may be used to coordinate the various tasks of the repair process and the costing of them. However, the details of such tasks are not relevant to the present invention and they will not be discussed further here. When all the details have been input, they are stored in the database at step 50.

[0024] The system is now ready for paint to be mixed in step 54, which operation is carried out in association with the weighing machine 12 and described below with reference to Figure 3. In step 52, before or after mixing of the paint in step 54, the control computer instructs the label printer 22 to print identification labels for the paint cans.

[0025] When it is determined in step 54 that all the paints necessary for the desired paint structure have been formulated, the paint mixing stage of the process is at an end. Step 56 shows that after use of the respective paints to create the desired paint structure on the vehicle component, the actual time taken for the paint job is input and is recorded by the control computer 10. That allows a true costing of the paint job to be carried out, in addition to statistical analysis comparing the allowed times with the actual times for each job and perhaps for different operators. Similar recordal of allowed and actual times may be carried out for other tasks in the vehicle repair job. On the basis of these results, management reports may be generated in step 58, using the printer 15.

[0026] The printer 15 may also be used to print a record concerning the paint formulation for a repair job record card. Alternatively, the progress of the repair job may be recorded and monitored purely electronically, through the control computer 10.

[0027] The process of mixing paint will now be described with reference to Figure 3. In step 37, the job reference is input to the weighing machine 12, either using built-in input means (not shown) or via the input means 14 connected to the control computer 10. Using the job reference, the weighing machine 12 retrieves from the database the paint details for the appropriate job in step 38. In step 39, the machine determines the formula of paint components required to formulate the input paint structure.

[0028] In step 40 the weighing machine 12 determines whether the retrieved paint formula can be formulated within the constraint fixed by the input cost limit. If in step 40 it is determined that the cost of the paint formula will exceed the cost limit, operation of the weighing machine is suspended and the process passes to step 41. A manual override signal may be given, e.g. by a supervisor with a password, to allow operation of the machine 12 to continue at step 42. If no such override signal is given, the formulation process is ended by physically disabling operation of the weighing machine 12.

[0029] In step 42 the weighing machine 12 prompts the operator of the machine on the display 18 to add a specified amount of the first paint component to the formulation. Feedback from the weighing device 20 informs the weighing machine computer how much of the paint component has been added.

[0030] In step 43 the weighing machine 12 determines whether there are further paint components to be added to the formulation. If so, the operator of the weighing machine is prompted in step 44 to add an appropriate amount of the next paint component and the process returns to step 43. Optionally, an additional step (not illustrated) between steps 43 and 44 may determine from the input of the weighing device 20 whether the operator of the weighing machine has added the correct amount of the previous paint component. If necessary the formula may be revised to take account of errors by the operator. This in turn may require re-evaluation of whether the cost limit is likely to be exceeded in a step analogous to step 40, with the possibility of physically halting the paint mixing process if the new formulation exceeds the specified limit.

[0031] If in step 43 it is determined that no further paint components are required, the paint mixing is at an end and the vehicle can be painted in accordance with the input paint structure at step 45.

[0032] On completion of the paint job, any waste paint remaining will need to be recycled. Optionally, the waste paint can be weighed at step 46 using the weighing machine 12 so that the amount of waste paint can be related to the job reference.

[0033] Finally, the process passes to step 47, in which the total cost of the paint is recorded in the database for subsequent retrieval. If the waste paint for recycling has been weighed, that information is also sent to the database. As previously explained, the cost of the paint and the volume of the paint are equivalent and, where the conversion factor is known, either may be used. Generally, a commercial paint weighing machine will measure paint by volume and the conversion to cost values will occur in the control computer 10.

[0034] It will be appreciated by the skilled reader that the apparatus allows the managers of the repair shop to exercise control over the cost of paint used, instead of merely reacting after a cost limit has been exceeded. In addition, the facility for recording the actual cost of paint used and the actual time spent allows the managers to carry out statistical analysis to identify the source of any inefficiency and perhaps target the training of estimators or machine operators appropriately.

[0035] Recordal of the waste paint left over after completion of each paint job allows the efficiency of the operators and the accuracy of the estimating algorithms to be assessed. It also assists in planning for recycling or disposal of the waste paint and in accounting for the pollutants handled.

[0036] It will readily be understood how the embodiment of the invention described here can be adapted for controlling the use of solvents or other environmental pollutants. Instead of inputting a maximum cost for each paint used, the user inputs a maximum amount of solvent to be used. By knowing the solvent content of each of the paint components, the maximum amount is converted to a maximum volume (or weight) for each paint. The test at step 40 then becomes a determination of whether the specified pollutant limits are likely to be exceeded, in which case operation of the weighing machine is physically disabled. Indeed, several limits could be input, for both cost and one or more pollutants, and the weighing machine could be disabled if any of the limits were to be exceeded.

[0037] In this case, the invention allows for the first time the control of a paint weighing machine to comply with environmental regulations against excessive use of polluting chemicals. The physical result is that less of each polluting chemical is used and less is wasted, avoiding problems and costs associated with disposal of waste. In addition, the recording facilities provide a means for proving the levels of chemicals actually used, thus allowing enforcement of a "polluter pays" policy or implementation of the "best available technique not exceeding excessive cost" principle.

[0038] Another change that could readily be made to the invention as herein described would be for the weighing machine to be controlled in response to a global limit on the paint property for the whole paint structure. That global limit could be either instead of or in addition to the limits for individual paints. In this way, an overestimate for one paint could be compensated by an underestimate for another.

Claims

1. Paint mixing apparatus comprising:

input means (14) for inputting a desired paint composition; and

formulation means (12) for formulating the desired paint composition from a set of paint components;
CHARACTERIZED BY

input means (14) for inputting a limiting value of a paint property; and

control means (10) for monitoring a cumulative value of the paint property for the paint components used by the formulation means (12) and for suspending operation of the formulation means (12) if the cumulative value of the paint property exceeds the limiting value.

2. Paint mixing apparatus according to claim 1, further comprising override means, by which an operator can allow operation of the weighing machine (12) to continue after operation has been suspended by the control means (10).

3. Apparatus according to claim 1 or claim 2, including means for recording the limiting value and the final cumulative value of the paint property.

4. Apparatus according to any preceding claim, further comprising a printer (15) for printing a record after the paint has been mixed.

5. Apparatus according to any preceding claim, further comprising a printer (22) for printing a label for the paint that has been mixed.

6. Apparatus according to any preceding claim, further comprising input means for inputting a paint structure that consists of one or more paints to be formulated by the formulation means (12).

7. Apparatus according to any preceding claim, wherein the control means (10) is a computer for managing vehicle repair jobs, the apparatus further including input means (14) for inputting a job reference to identify the repair job for which the paint is to be mixed.

8. Apparatus according to any preceding claim, wherein the paint property is the cost of the paint.

9. Apparatus according to any preceding claim, wherein the paint property is the solvent content of the paint.

Drawing