WO2006128391A1 - Method and device for optimizing the operating speed - Google Patents

Abstract

In a conventional method, the data required for calculating the optimal operating speed is determined in tests and is summed up in standard tables that are used for reducing the production costs. The aim of the invention is to improve said method such that the method yields more accurate results. Said aim is achieved by the fact that the operating speed is modified in systematic steps until the optimal operating speed has been determined with the desired accuracy. The inventive method and device do away with the inaccuracy generally associated with the use of standards. The invention can be applied in all production processes in which there is a correlation between the operating speed and the downtime of the tool and/or the service life of the machine.

Description

 METHOD AND DEVICE FOR OPTIMIZING WORKING SPEED

The invention relates to a method for optimizing the working speed, in particular during production, and to a device for carrying out this method.

The method can be used in all manufacturing processes in which a dependency exists between the working speed and the service life of at least one of the components of the production device. These production processes are essentially named in DIN 8589, Issue 3.81.

As the working speed increases, the machining time decreases. The cost of time required for machining a workpiece is reduced. At the same time, however, the load on the tool and the machine increases. It shortens the life of the tool and the life of the machine or individual parts of the machine. The proportion of the cost of the tool and the machine attributable to a workpiece increases.

By reversing the cost of machining time and the tool and machine costs as the operating speed changes, there is an optimal work rate that results in the lowest overall machining cost.

Conventionally, at least in the field of machining, the constants for formulas are determined by means of which the optimum working speed can be calculated (see VDI Guideline 3321, Issue 3.94, page 3, point 2.3). The test results are ordered according to process, workpiece and tool properties in O

Benchmark tables used to reduce production costs. This approach is inaccurate because the formulas used only approximate reality. Furthermore, the circumstances of the individual case are disregarded, since the conditions under which guideline values are determined are only exactly available in individual cases during production.

The invention has for its object to improve a generic method for optimizing the operating speed so that the process leads to a more accurate result, resulting in a significant cost savings. Another object of the invention is to provide a device for carrying out this method.

These objects are achieved by the characterizing features of claims 1, 3, 7 and 9. Advantageous developments of the method and the apparatus for carrying out this method are characterized in the subclaims.

The core idea of the invention is that it is possible to improve the accuracy with which the optimum operating speed is determined by preferably systematically changing the operating speed based on operating speed-dependent characteristic numbers.

The efficiency of the process increases considerably if it is carried out completely or partially automatically. Through automation, the process can be simplified and accelerated in such a way that it can be carried out economically during ongoing production on a regular basis whenever a production process operates under changed conditions, whereby all conditions of the individual case are taken into account. It is no longer necessary to work with reference values.

The optimal working speed depends on a large number of factors that are not covered by guideline values. which were determined in representative manufacturing processes. For example, in machining, the amount, flow direction and composition of the coolant, changing cutting data, frequent cuts, cut breaks, a forged, rolled or cast skin, the workpiece geometry dependent on the thermal conductivity of the workpiece, in terms of analysis, the strength and the structure of different material supplies and the state and stability of the workpiece, workpiece clamping, machine and tool clamping system existing system influence the optimal working speed in a no longer negligible order of magnitude.

In the initially described variant of the method according to claim 1, the operating speed is adjusted in such a way that the optimum operating speed can be determined by comparing the characteristic numbers, based on the operating speed-dependent characteristic numbers.

In the process, the key figures that result when working at different speeds are determined. Furthermore, the key figures are assigned to the working speeds.

A key figure is preferably assigned to a working speed by calculating the key figure with at least one of these working speed directly or any indirectly dependent size and / or working speed itself and none, one or more other sizes. The key figure can be calculated exactly or iteratively. The key figure can also be assigned explicitly or implicitly. It is also possible to assign a single code, calculated for example as a mean value, to several operating speeds.

In order to determine the optimum working speed as the working speed, which has been assigned the smallest or the largest index, depending on the nature of the key figures, the working speeds are assigned Key figures compared.

The change in operating speed, the determination of key figures and the comparison of the key figures is done until the optimum working speed is found in the desired accuracy.

In this case, according to the invention, the operating speed is changed in such a way that the optimum operating speed can be found as a function of the previously assigned characteristic numbers. Furthermore, according to the invention, the operating speed is preferably changed systematically in order to minimize the number of times the operating speed has to be changed.

For this purpose, if necessary, the working speed is changed only in the direction leading to the optimum working speed. This is the direction in which the associated measures have so far approached an at least relative minimum or maximum.

When the optimum operating speed is limited, the range at the optimum operating speed will go through with a decreasing increment of the working speed until the optimum operating speed is sufficiently accurately determined.

In an advantageous embodiment of the method working speeds are selected according to the claim 2 in the limitation of the optimal operating speed, which are in the middle or near the middle between the working speeds, which were previously associated with key figures. This approach leads, on the fastest formal path, to the limitation of the optimal working speed.

The method can be based on any key figures, preferably costs, which change with the working speed. The term cost is synonymous with all the costs that are affected by the speed of work, such as machining, manufacturing, production, manufacturing, or cost. The method may be based on other amounts instead of costs that are part of the costs or that include the costs or that approximate the costs or that are related to the costs, such as the raw or the selling price ,

Among other things, the optimal working speed can also be described as the cheapest, most cost-effective, most effective, time-optimal or cost-optimal working speed.

Alternatively, the variant of the method can be selected according to claim 3, in which the optimum operating speed is determined by a change in the operating speed, which is based on a ratio that is equal to the value of the previously determined optimal operating speed.

It is at least as often worked at different speeds, as necessary, so that all sizes can be determined, which are required to determine the ratio.

When enough data is collected, the measure can be calculated and, preferably, assigned to the operating speeds on which the data on which the measure was calculated depends. The measure may also be explicitly or implicitly assigned to one or a portion of or all of the operating speeds underlying its determination. The measure can be calculated exactly or iteratively.

Now work is done with at least one speed which is equal to the previously determined characteristic number or which is close to the previously determined characteristic number. In order to more accurately determine the optimum operating speed as the operating speed, which is equal to the characteristic number, the characteristic value is again determined according to the invention, taking into account the data determined by the production with the operating speed / s oriented on the characteristic number.

In order to continue the more precise determination of the characteristic number or at least to produce the more accurately determined optimum working speed, according to the invention at least one further speed is used, which is equal to the again determined characteristic number or which is close to the again determined characteristic number.

The change of the working speed oriented to the key figure, the updating of the data required for the determination of the key figure and the renewal of the key figure occur until the key figure is found in the desired accuracy.

The metric is typically more accurate when constrained by the operating speeds at which it was determined.

Therefore, in an advantageous embodiment of the method according to claim 4, the operating speed is changed such that the probability increases that a key figure, which is not limited by the selected for their determination working speeds, is limited by the future selected for their more accurate determination of working speeds.

For the same reason, in an advantageous embodiment of the method according to claim 5, the operating speed is changed such that the probability increases that an index, which is already limited by the selected for their determination work speeds, by the future selected for their more accurate determination of working speeds remains limited. The metric is typically more accurate when all working speeds are close to where it was determined.

If different speeds with which work has hitherto been carried out are available for the determination of the characteristic number, for the abovementioned reason, in an advantageous development of the method according to claim 6, the more precise determination of the characteristic number is based on those working speeds which close to the previously determined indicator.

The method can be accelerated by carrying out with the aid of several production facilities, wherein the same manufacturing process takes place on each production facility and manufactures each production facility at a different operating speed.

If the operating speed of the production device, on which the method is performed, is controllable via a program-controlled electronic control device, the method can be completely or partially automated with little effort by means of this already existing control device, resulting in a further cost savings.

If there is no possibility for automation, then the method can be carried out at least computer-aided by a computer performing the calculations, requesting the data required for this purpose by a person and requesting a person to carry out the operations necessary for carrying out the method. This relieves the person responsible for the procedure, as it does not have to deal with the details of the execution and the physical background of the procedure.

The device for carrying out the method according to claim 7 or 9 consists of at least one production device whose working speed over at least one preferably program-controlled electronic control device is controllable. The control device may consist of individual devices which are connected and which act together.

The device according to claim 7 or 9, the codes are supplied for further processing, which have resulted in speeds with which the manufacturing device has worked. If the device is capable of performing calculations, the device may also be provided with the data required to calculate the codes. The key figures are then calculated by the device itself. In the best case, the device controls the determination of the data required to calculate the key figures.

The device according to claim 7 has a program which according to the invention is capable of controlling the change in the operating speed of the production device in dependence on characteristic numbers such that the optimum operating speed can be determined by comparing characteristic numbers.

In an advantageous embodiment of the device according to claim 7, the device according to claim 8 has a program that is able to change the operating speed of the manufacturing device such that the optimal working speed is limited in the fastest formal way by the change Working speeds are chosen to be working speeds that are in the middle or near the middle between the working speeds to which a metric has been assigned.

According to the invention, the program possessed by the device according to claim 9 is able to control the operating speed of the production device in such a way that the production device operates at a speed which is equal to or close to a characteristic number that by changing the operating speed, the index can be determined more accurately. In an advantageous embodiment of the device according to claim 9, the device according to claim 10 has a program that is able to control the change in the operating speed of the manufacturing device such that a not limited by the selected working speeds for their determination of operating characteristics by the future their more precise determination of selected working speeds is likely to be limited.

The device according to claim 11 has in an advantageous embodiment of the device according to claim 9 or 10 via a program that is able to change the speed of the manufacturing facility such that a limited by the selected working speeds for their determination by the future for their more accurate determination of selected working speeds is likely to be limited.

In an advantageous embodiment of the device according to claim 9, 10 or 11, the device according to claim 12 has a program which is able to control the change in the operating speed of the manufacturing device such that the more accurate determination of the index are based on those operating speeds, which are close to the previously determined indicator.

The program of the device according to claim 7, 8, 9, 10, 11 or 12 may consist of several complementary and / or cooperative programs.

In the following, the invention will be explained in detail by means of concrete examples, which do not claim to be universal and which are based on the cutting production.

It optimizes the component of the working speed with which a particular tool works. If the workpiece is machined with additional tools, the production be optimized by the process is also performed for the components of the working speed with which the other tools work.

As the characteristic needed to control the process, the processing costs are used.

Preferably, at the beginning of the process, the quantities which are needed in the course of the process and remain unchanged are collected. These are the machine costs per hour and the tool costs per tool life. To calculate the machine costs per hour and the tool costs per tool life, the VDI guideline 3321, Issue 3.94, S. 11, T. 8, S. 4, Ziff. 3.1.1 serve as orientation.

The processing time is determined, which results when the machine manufactures with a starting value for the working speed. From the beginning of production with a new tool, the amount of stock that the tool can process at the starting value of the working speed can be determined.

After the machining time and the stall quantity have been determined, the costs that result when manufacturing with the starting value of the operating speed can be calculated.

The costs (K = M x t + W / m) can be calculated with the machine costs per hour (M), the machining time per workpiece (t), the tool costs per tool life (W) and the tool life (m). (See VDI Guideline 3321, Issue 3.94, page 4, point 3.1.2)

If the working time and the stall quantity and thus the quantities required for the calculation of the costs are known for a working speed, then a new speed can be used, which differs from the previously selected working speeds. While the machine is producing at a new operating speed, it is possible to determine the machining time and the amount of stall that results at this current operating speed.

After the processing time and the stall quantity have been determined, the costs resulting from the production at the current operating speed are calculated in the manner described above.

To determine the optimal working speed, the costs calculated for the individual working speeds are compared with each other.

The change of the working speed, the calculation of the costs and the comparison of the costs is repeated until the optimum working speed is found in the desired accuracy.

In particular, in order to minimize the number of times the operating speed has to be changed, the operating speed is changed in targeted steps, as described below.

The first two working speeds, which start the search for the optimum working speed, generally have to be freely chosen.

If it is assumed that the optimum working speed is between the first two working speeds, it is expedient for the third speed to be set to a value which is preferably in the middle between the first two working speeds.

If the costs that resulted at the first and second operating speeds are higher than the costs that have arisen at the third operating speed, then the optimum operating speed is through the first two Working speeds already limited. In this case, changes in working speed resulting in the optimum working speed are not required. Then, the optimum operating speed, more precise changes in the operating speed are necessary, as described later.

On the other hand, if the costs that resulted at the first and second operating speeds are below and above the costs that have arisen at the third operating speed, then the optimum operating speed is outside the range limited by the first two operating speeds , In this case, changes in the working speed leading to the optimum working speed are required, as described first.

If it is assumed that the optimum operating speed lies next to the first two working speeds, it is expedient for the third speed to be set to a value that results when, starting from the operating speed at which the lowest costs have hitherto arisen, the Working speed is changed in the direction in which the costs have fallen so far.

If the costs that have arisen at such a selected third operating speed have also fallen, then in the case of the initially following changes in working speed, the operating speed is also changed in the direction in which the costs have fallen so far.

The change in the working speed in this direction leading to the optimum working speed is maintained until the costs rise again.

In this case, the optimal working speed is limited by the three last selected working speeds. At a skilful choice of speeds, with When the search for the optimal working speed has begun, this situation can already occur after working at three speeds.

Now, the range between the last three selected working speeds can be traversed with a smaller increment of working speed until the optimum working speed is more accurately limited.

Preferably, operating speeds are chosen that are midway or near the middle between two of the previously selected operating speeds, as this is the fastest formal approach for limiting the optimum operating speed.

If the optimum operating speed is narrowed down in this way, it is possible to proceed again as described above in order to limit the optimum operating speed even more precisely.

In doing so, the range bounded by the two working speeds, between which the working speed, at which the lowest costs have hitherto arisen, is traversed with less than the previous steps of the working speed.

This approach, which limits the optimum working speed, can be continued until the optimum operating speed has been determined with sufficient accuracy.

Alternatively to the determination of the optimum operating speed according to the variant of the method according to claim 1, as described in the above example, the variant of the method according to claim 3 can be selected, as explained below with reference to a further example.

For example, when turning, drilling or milling, the relationship between the cutting speed (V) and the service life of the tool (T) with a factor (c) and an exponent (e) by a guideline equation in exponential form (V = cx T ^A (l / e)).

The optimum cutting speed (Vo = cx ((- e - 1) x W / M) ^Λ (l / e)) can be calculated by the factor and the exponent for the standard equation, the tool cost per tool life (W) and the machine cost per hour Calculate (M). (See VDI Guideline 3321, Issue 3.94, p. 8)

For the optimal cutting speed to be calculated, the factor and the exponent must be known.

In order to be able to calculate the factor and the exponent, two different cutting speeds are used and the tool life is determined for each of these cutting speeds.

After determining the associated service lives for two cutting speeds, the factor and exponent for the benchmark equation can be calculated.

If the factor and the exponent are known, the optimal cutting speed can be calculated.

The chosen guideline equation (V = cx T ^A (1 / e)) only approximates reality. Therefore, the optimum cutting speed can be determined inaccurately. This is particularly the case when the cutting speeds chosen to determine the optimum cutting speed are far apart or are far away from the optimum cutting speed calculated on their basis.

In order to more accurately determine the optimum cutting speed, at least one new cutting speed is produced which is equal to the previously calculated optimum cutting speed or which is close to the previously calculated optimum cutting speed. When manufacturing at the new cutting speed, the tool life with which the tool operates at this cutting speed is determined.

Based on the new cutting speed and one of the cutting speeds selected up to now and the service lives determined at these two cutting speeds, the factor and the exponent for the standard value equation are recalculated.

With the newly calculated factor and exponent a new improved value for the optimal cutting speed is calculated.

Manufacturing with a cutting speed oriented at the previously determined optimum cutting speed, updating the data required to calculate the optimum cutting speed and thereby recalculating the optimum cutting speed is repeated until the optimum cutting speed is found in the desired accuracy.

In this case, the algorithm with which the optimum cutting speed is calculated can be changed in comparison with the previously used algorithm. An algorithm can be chosen that takes into account the data obtained at more than two of the previously selected cutting speeds. Furthermore, based on the previous measurement results, an algorithm can be chosen that describes the reality in more detail.

In the same way, the optimum feed rate can be determined. In addition to the cutting speed as an additional component of the working speed, the feed rate influences the service life of the tool.

In the following, the invention will be described with reference to an embodiment. Game and associated figures explained in more detail. Show

Fig. 1 shows the relationship between cutting speed and

2, the determination according to the invention of the optimum working speed in a schematic representation,

3 shows the determination according to the invention of the optimum operating speed on a concrete example.

The cost of machining time and the tooling costs are reversed as the cutting speed changes. As the cutting speed increases, the machining time is reduced and the costs are reduced. At the same time the load of the tool increases and the tool costs increase. Therefore, in terms of the total machining cost, which is composed of the tool cost and the cost of machining time, there is an optimum cutting speed. This relationship is shown in FIG.

In the following it is described how in the course of a series of experiments during the production of a series of workpieces for a particular tool, this optimum cutting speed can be determined, which leads to the lowest machining costs. The procedure for determining the optimum operating speed according to the invention is shown schematically in FIG.

For a production process to be optimized, the processing costs must first be calculated for the previously or any selected setting of the machine. Then, with an otherwise constant machine setting, the cutting speed can be changed in directed steps as long as the respective stall quantity resulting therefrom is determined, and thus the machining costs can be recalculated until the most cost-effective cutting speed is found. First of all, the machine sets the greatest cutting depth that is possible for the workpiece geometry to be produced and that allows the stability of the system consisting of workpiece, workpiece clamping, machine, tool clamping and tool. The workpiece is then machined with the least number of cuts and unnecessary return, infeed, start-up and overflow paths are avoided.

The maximum feed rate is set, with which the required surface quality of the workpiece can still be achieved and the largest wear mark width is selected, which allows the dimensional accuracy and surface quality of the workpiece. In addition, the cutting speed or speed is set, which is probably optimal or leads to the lowest processing costs. The more accurately the optimum speed is estimated, the lower the number of measurements needed to optimize the manufacturing process.

With these settings, a 1st measurement is carried out by determining the amount of stall that results at the set speed. For this purpose, the machine is stopped at appropriate time intervals to measure the wear mark width or other criterion selected for the end of tool life. When the desired wear mark width has been set on the tool, the required tool life is equal to the number of tools processed so far with the tool.

Subsequently, the processing costs for the current settings are calculated from the determined data. This calculation may include the machine costs per hour or / and the number of workpieces to be machined.

For example, tool life and procurement costs per tool can be taken into account when calculating tool costs.

Then, with a new tool, a 2nd measurement of Stall quantity carried out by further workpieces are processed. The second measurement is for the purpose of determining the direction in which the speed must be changed so that the processing costs decrease. For this purpose, a speed is set in the second measurement, which differs from the speed of the 1st measurement, and the stall amount, which results from the changed speed measured.

After completion of the second measurement, the processing costs are determined in an analogous manner, which result for the set at the 2nd measurement speed.

Based on the results of the 1st and 2nd measurement, a third measurement is performed to approach the optimum speed or, in the best case, to limit the optimum speed. The speed set in this measurement depends on the results obtained in the first two measurements, i. the speed is changed in the direction in which the machining costs have fallen in the previous two measurements.

If in the 2nd measurement, a speed was set which is greater than the speed of the 1st measurement, and the processing costs in the 2nd measurement are lower than the processing costs of the 1st measurement, a speed is selected in the 3rd measurement, which is greater than the speed of the 2nd measurement. In contrast, in the 3rd measurement, a speed is selected which is smaller than the speed of the 1st measurement, when in the 2nd measurement, a speed was set, which is greater than the speed of the 1st measurement, and the processing costs at the 2nd Measurement is higher than the processing cost of the 1st measurement.

If the speed was not increased from the 1st to the 2nd measurement, but was reduced, the speed is selected in an analogous manner for the 3rd measurement. In this case, in the 3rd measurement, the speed is increased from the speed of the 1st measurement when the machining cost has increased in the 2nd measurement compared to the machining cost of the 1st measurement. If at the second measurement, the processing costs have fallen compared to the processing costs of the first measurement, the speed is reduced compared to the speed of the 2nd measurement in the 3rd measurement.

After the end of the 3rd measurement, as previously explained, the processing costs will be recalculated. If the machining costs for the 3rd measurement are greater than the machining costs for the 1st or the 2nd measurement, no further measurements are necessary, which lead to the desired optimum speed, since the optimum speed is already limited and between the speeds which were set in the 1st, 2nd and 3rd measurement.

If the machining costs for the 3rd measurement are lower than the machining costs for the 1st and 2nd measurements, then the optimum rotational speed is outside the range that lies between the rotational speeds, that in the 1st, 2nd and 3rd measurement were set. In this case, it is necessary that further measurements be taken in the manner described above, which lead to the optimum speed. The speed is changed from measurement to measurement in the direction selected during the 3rd measurement. This is the direction in which the processing costs fell from the 2nd to the 3rd measurement.

When the speed has been increased from the 2nd to the 3rd measurement, the speed is increased; it is reduced if it was reduced in the third measurement compared to the second measurement.

These measurements leading to the optimum speed are made until the processing costs rise again. Then the cost-optimal speed is in the range between the speeds that were set last and before last.

In order to get closer to the optimal speed, further measurements can be made by changing the speed with smaller speed steps. Become half as big Steps selected as in the previous measurements, so previously taken measurements can be exploited. These experiments are continued until the difference between the lowest machining costs and the next higher machining costs is within the desired tolerance.

The method described for determining the optimum processing speed or speed is more accurate than a numerical calculation using the standard value equation, since the approximate equation only approximately describes the reality. However, the results obtained apply only to the wear mark width, the engagement ratio, the depth of cut and the feed rate at which they were determined. For workpieces whose processing requires different cutting data, they do not apply.

In Fig. 3, the inventive method is illustrated by a concrete numerical example. In the example, a plate is planed on a machining center. The calculations in the example are based on the following data.

The plate consists of the tempered steel (42CrMo4) with the number 1.7225 according to DIN 17007. It has a length of 200 mm and a width of 60 mm. Their surface is covered with a millet skin. The cutting zone has a hardness of 220 HB.

The tool is a face milling cutter for rough milling with positive square indexable inserts. It has the nominal diameter of 80 mm and is equipped with 5 indexable inserts. The setting angle is 75 ». The net price for the main body without indexable inserts is 287, - EUR.

The indexable inserts (SPKN 1504 EDR according to DIN 4987 / ISO 1832) have an edge length of 15.875 mm, which allows a maximum cutting depth of 12 mm. The inserts are made of coated carbide (HC-P25 according to DIN ISO 513). The net price for an indexable insert is 7.76 EUR. The rapid traverse speed of the machining center is 15 m / min for all axes. The machine is equipped with a tool change system. The time for an automatic tool change is approx. 4 sec. The machine costs are 60, - EUR per hour.

Since the workpiece is pre-milled and no special requirements are placed on its dimensional accuracy and surface quality, a feed per edge of 0.3 mm and a large wear mark width of 0.5 mm can be selected.

For the engagement ratio, the value of 0.75 results with the width of the workpiece (60 mm) and the diameter of the milling cutter (80 mm).

The milling path (L = 213.5 mm) can be determined by the length of the workpiece

(1 = 200 mm), the diameter of the tool (d = 80 mm) and the

Width of the workpiece (b = 60 mm) can be calculated. The return travel of 513.5 mm is greater than the feed path (300 mm) by the milling length (213.5 mm).

At the price of 7.76 EUR for an indexable insert, one of the 4 cutting edges of the plate costs 1.94 EUR. After the end of the service life, a change of the 5 active cutting edges of the milling cutter costs 9.70 EUR.

The procurement costs of EUR 296.70 for the ready-to-use face milling cutter consisted of the basic body price (EUR 287) and the cost (EUR 9.70) of the first cutting equipment.

The operating costs for the tool such as the costs for administration, storage, transport, restoring, maintenance, repair and spare parts (screws, liners, clamping pieces, wrenches) are neglected in this example.

At the time required for the replacement of a cutting edge is, can be assumed from 45 sec, so that there are 225 sec for the entire plate rotation or change process at the 5 cutting edges of the milling cutter.

Since the workpiece is preprocessed and there are no special requirements for its dimensional accuracy, no time required for a face run control of the tool and a dimensional control of the workpiece after the Schneidausch must be considered.

Furthermore, it is assumed in this example that, in the context of a first measurement to optimize the above-described manufacturing process for the speed of 550 revolutions per minute results in a stall quantity of 179 pieces. With a total quantity of 100,000, this results in processing costs per piece amounting to 45,862, - EUR.

Number of blades: 5

Feed per cutting edge: 0.3 Wear mark width: 0.5

Engagement ratio: 0.75 Depth of cut: 12 Diameter: 80 Speed: 550

Workpiece: plate Material: tempered steel Substance number: 1.7225 Short name: 42 CrMo 4 Hardness: 220 HB

Quantity: 100000 Machine cost per hour: 60

Tool change time per workpiece: 4 Feed path per workpiece: 300 Feed speed: 15 Start-up distance per workpiece: 1.5 Drilling, milling or turning path per workpiece: 213.5 Overflow path per workpiece: 1.5

Return travel per workpiece: 513.5 Return speed: 15

Stand Quantity: 179

Tool: Face milling cutter for indexable inserts (SPKN1504EDR) Acquisition cost per tool: 296.7 Costs per resharpening or cutting edge change: 9.7 Regrinding / cutting edge change per tool: 10000 downtime per tool change: 225

Now, in this example, the speed previously set on the machine is increased by 80 revolutions per minute and it is assumed that with a second measurement for the speed of 630 revolutions per minute, the stall quantity is 149 pieces.

This results in the second measurement processing costs per piece of 44,046, - EUR.

Since the speed has been increased from the 1st to the 2nd measurement and the machining costs have dropped, the speed must be further increased in the 3rd measurement, so that the following measurements of the optimum speed come closer.

As part of the third measurement, the speed of 710 revolutions per minute results in a tool life of 127 pieces and a processing cost of 43,031, - EUR.

As long as the processing costs continue to fall as the speed increases, the speed from measurement to measurement is subsequently increased by the constant amount of 80 revolutions per minute.

At the 4th measurement the speed of 790 revolutions per minute results in a tool life of 110 pieces and the machining costs of 42.613, - EUR.

For the 5th measurement, the stall quantity of 96 pieces and the processing costs of 42,720, - EUR result for the speed of 870 revolutions per minute.

Since the machining costs have increased in the 5th measurement compared to the 4th measurements, the optimum speed lies between the speeds set in the 3rd and 5th measurements or between 710 and 870 rpm.

Now, the range between the speed of the 3rd measurement and the speed of the 5th measurement is passed through with steps that are 40 revolutions per minute and thus half as large as the steps with which the speed has been changed so far. In this case, either starting from the third measurement, the speed can be increased or, starting from the fifth measurement, the speed can be reduced, as will be described below.

For the 6th measurement, the speed of 830 revolutions per minute results in a tool life of 104 pieces and a processing cost of 42,439, - EUR.

Due to the speed step of 40 revolutions per minute, the next measurement would have to be made at a speed of 790 revolutions per minute. At this speed, the 4th measurement was previously made. This resulted in processing costs amounting to 42.613, - EUR and are greater than the processing costs of the 6th measurement.

The processing costs have fallen from the 5th to the 6th measurement. The 4th measurement resulted in higher processing costs than in the 6th measurement. For this reason, the optimum speed lies between the speeds set in the 4th and 5th measurements or between 790 and 870 revolutions per minute

Minute.

Therefore, below is the step size of the speed of 40 Reduced to 20 revolutions per minute and go through the range between the speed of the 4th measurement and the speed of the 5th measurement with this step size.

At the 7th measurement, the speed of 810 revolutions per minute results in a tool life of 107 pieces and a processing cost of 42.505, - EUR.

The next speed in the sequence is 830 revolutions per minute. The machining costs, which amount to 42.439, - EUR and are lower than the machining costs that resulted from the 7th measurement, were already determined for this speed at the 6th measurement.

Therefore, the speed is further increased to 850 rpm at the 8th measurement, resulting in a tool life of 100 pieces and a machining cost of 42,549.00 EUR.

The processing costs for the 7th and 8th measurement are higher than the processing costs for the 6 measurement. The area in which the optimum speed is located is further limited by this measurement result. It lies between the speeds of the 7th and 8th measurement or within 810 and 850 revolutions per minute.

The processing costs, which were determined in the 7th measurement, are only about 0.16% higher than the processing costs of the 6th measurement. Further measurements can no longer be expected to bring about any improvement that would have any practical significance. The measurements for determining the optimum speed can be terminated.

The optimum speed is now the speed at which the lowest machining costs were determined within the scope of the previous measurements. This is the speed set at the 6th measurement. It is 830 revolutions per minute.

In the example considered, only 8 measurements made during on-going manufacturing were easy to measure Quantity required to reduce the processing costs irα compared to the speed set at the beginning of the measurements by approx. EUR 3,400.

Claims

Method for optimizing the working speed and device for carrying out the method patent claims 1. A method for optimizing the working speed, characterized in that at least twice at least one speed was worked with, a number not equal to the value of this speed, preferably the value of the processing costs is assigned by preferably thereby a speed is assigned a number in that the number is calculated with at least one of this speed directly or any indirectly dependent size and / or this speed itself and none, one or more other sizes, and that - is operated with at least one further speed which is less than or greater than two If the larger of the two speeds has been assigned a number smaller than the number, that is, the smaller of the two Geschwin If the smallest of the two speeds has been assigned a number, the system will search for the speed that will be assigned the smallest number, or work with at least one other speed that is less than two speeds is less than the number assigned to the larger of the two speeds and looking for the speed to which the smallest number will be assigned or operating at least one more speed greater than two speeds, if the major In addition, when the two speeds have been assigned a number greater than the number assigned to the smaller of the two speeds, and when searching for the speed to which the largest number will be assigned, or operating at least one more speed , which is less than two speeds, if the smaller of the two speeds has been assigned a number greater than the number assigned to the larger of the two speeds, and if the speed associated with the largest number is searched for or working with at least one other speed between two speeds to which numbers have been assigned, or operating at least one further speed between two speeds to which two numbers have been assigned, both greater or less which are both smaller than the number that egg was assigned to a speed that lies between the two speeds. A method according to claim 1, characterized in that for the further speed or for at least one of the further speeds a speed is chosen which is equal to a central speed or which is close to a central speed or which is closer to a central speed, when it is at a different speed to which a number has been assigned, where at a central speed is a speed that is midway between two speeds to which a number has been assigned. 3. A method for optimizing the working speed, in which - at least two speeds worked, a number, preferably the value of the optimum speed is assigned by preferably by a speed is assigned to a number by the number with at least one of this speed directly or any indirectly dependent size and / or this speed itself and none, one or more other sizes is calculated, and in which - worked with at least one additional speed equal to the number or close to the Number or closer to the number than the speed which is farthest from the number and which belongs to the speeds to which the number has been assigned, characterized in that at least two speeds worked with and among which additional speed or at least one of the additional speeds is assigned a further number, preferably by a speed is assigned to a number by the number of at least one directly or indirectly dependent on this speed size and / or this speed itself and no it is calculated, one or more other quantities, and that - is operated with at least one further speed, which is equal to the further number or which is close to the other number or which is closer to the other number than the speed, the furthest is removed from the further number and belongs to the speeds to which the further number has been assigned. 4. The method according to claim 3, characterized in that for the further speed or at least one of the further speeds, a speed is selected which is greater than the further number, when all speeds to which the further number has been assigned smaller than the further number or, for the further speed or at least one of the further speeds, a speed is chosen which is smaller than the further number, if all the speeds to which the further number has been assigned are greater than the further number. 5. The method according to claim 3, characterized in that for the further speed or at least one of the further speeds a speed is selected which is greater than the further number, if the further number between see two speeds is, which assigned the further number and the larger of these two speeds is further than the smaller of these two speeds from the further number, or that for the further speed or at least one of the further speeds a speed is chosen which is smaller than the further number, if the other Number is between two speeds to which the further number has been assigned, and the smaller of these two speeds is further than the larger of these two speeds from the other number away. A method according to any one of claims 3 to 5, characterized in that the further number is associated with the speed (s) closest to the additional speed (s), and / or that the further number of / is assigned to the speed (s) closest to the number assigned to the additional speed (s). 7. An apparatus for carrying out a method for optimizing the working speed, in particular according to claim 1, with at least one production device, comprising - at least one control device which is capable of changing the operating speed of the production device, and having at least one program, characterized that the program is capable of: - assigning a number not equal to the value of this speed, preferably the value of the processing costs, at least twice at least one speed at which the production facility has worked, and that the program in the It is able to set at least one further working speed at the production device which is less than or greater than two speeds, to which numbers have been assigned, and / or that the program is able to set at least one further working speed at the production device, which is in the search If the larger of the two speeds has been assigned a number that is less than the number assigned to the smaller of the two speeds, and / or that is assigned by the speed to which the smallest number will be assigned Program is able to set at least one further working speed at the manufacturing facility, which is less than two speeds in the search for the speed to which the smallest number will be assigned, when the smaller of the two speeds is assigned a number which is smaller than the number that was has been assigned to the larger of the two speeds, and / or that the program is capable of: - setting at least one further operating speed at the production facility which is greater than two speeds in the search for the speed to which the largest number will be assigned if the greater one of the two speeds has been assigned a number greater than the number assigned to the smaller of the two speeds and / or the program is capable of adjusting at least one further operating speed at the manufacturing facility is less than two speeds when the smaller of the two speeds has been assigned a number greater than the number assigned to the larger of the two speeds; and / or that the program is capable of at least one more ar to set the working speed at the production facility between two speeds to which numbers have been assigned, and / or that the program is capable of carrying out at least one further working speed on the production line. setting device that is between two speeds to which two numbers have been assigned, both larger or both smaller than the number assigned to a speed that lies between the two speeds. A device as claimed in claim 7, characterized in that the program is capable of setting, for the further speed or for at least one of the further speeds, a speed at the production device which is equal to a central speed or which is close to a central speed or which is closer to a central speed than it is at another speed to which a number has been assigned, where a central speed is to be understood to mean a speed midway between two speeds to which a number has been assigned , 9. An apparatus for carrying out a method for optimizing the working speed, in particular according to claim 3, with at least one production device, with at least one control device which is able to change the operating speed of the manufacturing device, and with at least one program, characterized in that the program is capable of assigning a number, preferably the value of the optimum speed, to at least two speeds with which the production equipment has worked Program is able to set at least one additional operating speed at the manufacturing facility which is equal to the number close to the number or closer to the number than the speed furthest from the number and the belongs to the velocities to which the number has been assigned and that the program is capable of having at least two speeds at which the has worked and under which the additional speed or at least one of the additional speeds is included to assign a further number, and that the program is able to - set at least one further operating speed at the manufacturing facility, which is equal to the other number or is close to the further number or closer to the further number than the speed which is farthest from the further number and belongs to the speeds to which the further number has been assigned. 10. The device according to claim 9, characterized in that the program is able - for the further speed or at least one of the further speeds to set a speed at the production device which is greater than the further number, if all the speeds to which the has been assigned an additional number, are smaller than the further number, and / or that the program is able to set a speed at the manufacturing facility for the further speed or at least one of the further speeds which is smaller than the further number, if all Speeds to which the additional number was assigned are greater than the additional number. 11. The device according to claim 9 or 10, characterized in that the program is able to set for the further speed or at least one of the further speeds, a speed at the manufacturing facility, which is greater than the further number, if the additional number between is two speeds to which the further number has been assigned, and the greater of these two speeds is further away than the smaller of these two speeds from the further number, and / or that the program is capable of further speed or at least one of the other speeds, a speed at the production setting device which is smaller than the further number, if the further number is between two speeds to which the further number has been assigned, and the smaller of these two speeds is further away from the further number than the larger of these two speeds. Device according to any one of Claims 9 to 11, characterized in that the program is capable of assigning the further number of speeds / speeds closest to the additional speed (s), and / or that the program is able to allocate the further number of the speed (s) closest to the number assigned to the additional speed (s).