Machine tool with temperature control system

Abstract

The invention relates to a machine tool with a temperature control system (2) configured for temperature control of different areas of the machine tool, wherein the temperature control system (2) comprises: a tank (3) filled with a temperature control fluid, a pump (4) for pumping the temperature control fluid from the tank (3), a temperature control circuit (10, 20, 30, 40, 50) for each area of ​​the machine tool to be temperature controlled, each temperature control circuit returning to the tank (3), a branch (111) connected to the pump (4), a cooling source (7) connected to an inlet (70) of the cooling source (7), and a mixing valve (11, 21, 31, 41, 51) arranged in each temperature control circuit (10, 20, 30, 40, 50), each mixing valve having a first inlet (81), which is connected to the branch (111), a second inlet (82) which is connected to the cold source (7) and an outlet (83),which leads to the temperature control circuit, and a control unit (8) which is configured to set a predetermined target temperature for each temperature control circuit by means of the mixing valves (11, 21, 31, 41, 51).

Description

[0001] The present invention relates to a machine tool with a temperature control system for cooling and / or heating areas of the machine tool.

[0002] Due to increasing accuracy requirements, geometric changes in machines caused by fluctuating ambient temperatures at the machine's installation location are becoming increasingly important, especially when the machine tool is not operated in an air-conditioned room or in a room with air conditioning, but this room has fluctuating temperatures despite the air conditioning. In air-conditioned rooms or halls, temperature stability is usually no better than + / -1° Celsius or even + / - 2° Celsius over the course of the day. This leads to significant thermally induced geometric changes in the machine and, as a result, undesirable machining inaccuracies because the machine is exposed to the changing temperature throughout the day.With the new temperature control unit, it is possible to temperature control different areas of the machine in a very efficient way, so that temperature fluctuations at the machine's installation location no longer have any or hardly any effect on the machine's geometry.

[0003] Machine tools with cooling devices are known, for example, from DE 10 2008 009 513 A1, DE 10 2012 014 236 B3 and DD 207 166 A1.

[0004] It is therefore an object of the present invention to provide a machine tool for machining workpieces which, with a simple structure and simple, cost-effective manufacture, has the highest temperature independence during machining in order to meet the highest precision requirements during machining.

[0005] This object is achieved by a machine tool having the features of claim 1. The subclaims show preferred developments of the invention.

[0006] The machine tool according to the invention for machining workpieces with the features of claim 1 has the advantage that, by means of an improved temperature control system, the highest precision requirements in the machining of workpieces are met. This enables ultra-precision machining of workpieces in a reliable manner. The temperature control system according to the invention requires relatively few and simple components and can be easily integrated into a machine tool. This allows the additional costs of the temperature control system according to the invention to be kept low. Furthermore, electrical components in the temperature control system, e.g., Peltier elements or the like, can be dispensed with.

[0007] The temperature control system according to the invention is designed to control the temperature of various areas of the machine tool. The areas of the machine tool can be, for example, a drive, a workpiece table, a machine bed, a Z-column, a hood or housing, a Z-axis with spindle, a work area, or the like. The temperature control system according to the invention can reliably and with the highest precision control the temperature of both components of the machine tool and, for example, air-filled areas such as the work area. Each area is controlled by means of a separate temperature control circuit. The temperature control system comprises a tank, a pump for pumping a temperature control fluid from the tank, and a temperature control circuit for each area to be temperature controlled. Each temperature control circuit leads back to the tank. Furthermore, the temperature control system comprises a branch in a line connected to the pump.The temperature control system further comprises a cold source, wherein the branch is connected to an inlet of the cold source. In each temperature control circuit of the temperature control system, a mixing valve is arranged downstream of the branch and the cold source in the flow direction. Each mixing valve has a first inlet connected to the branch, a second inlet connected to the cold source, and an outlet connected to one of the temperature control circuits. The mixing valve is configured, on the one hand, to mix a mixture of temperature control fluid from the cold source and the tank and, on the other hand, to enable complete shutoff of the connection to the cold source or the tank. The temperature control system further comprises a control unit configured to set a predetermined target temperature in each temperature control circuit by means of the mixing valves.

[0008] The respective target temperature depends on the actual temperature in the respective area of ​​the machine tool. If the actual temperature in the respective area of ​​the machine tool corresponds to the target temperature, the control unit can also completely close the mixing valve, preventing the temperature control of the area of ​​the machine tool that has the correct temperature.

[0009] If the machine tool releases a relatively large amount of heat to the temperature control circuits during operation, the temperature control fluid in the tank will heat up to such an extent that it exceeds the highest target temperature of one of the temperature control circuits. If this happens relatively quickly, a heat source in the temperature control system can be dispensed with.

[0010] Preferably, a heat source is arranged between the branch and the first inlets of the mixing valves. The heat source is configured to heat the temperature control fluid supplied to the inlets of the mixing valves.

[0011] Alternatively or additionally, the heat source can also be located in the tank. In this case, for example, before the machine tool is switched on, the temperature control fluid is heated to such an extent that it exceeds the highest target temperature of one of the temperature control circuits. During machine tool operation, the heat source can then be switched off, as the heated temperature control fluid from the return lines keeps the temperature in the tank sufficiently high.

[0012] Further preferably, at least one temperature control circuit directly controls the temperature of an area of ​​the machine tool. This directly temperature-controlled area is preferably a machine bed or a Z-column of the machine tool. Due to their size, these areas of the machine tool provide sufficient space for the integration of a heat exchanger with, for example, meandering pipe sections for the temperature control circuit.

[0013] Further preferably, a liquid-to-air heat exchanger is arranged in at least one temperature control circuit to temperature-control at least one region of the machine tool using air. The liquid-to-air heat exchanger makes it possible, for example, to temperature-control air-filled regions of the machine tool. The temperature-controlled region of the machine tool is preferably the working region of the machine tool.

[0014] Particularly preferably, the air tempered by the liquid-air heat exchanger is used as sealing air in a predetermined area of ​​the machine tool. This can be, for example, at a Z-axis with a spindle or at a machining location for blowing away chips or the like, or the sealing air can be used near an oil mist extraction area to direct the oil mist in a predetermined direction.

[0015] According to a further preferred embodiment of the invention, the temperature control system comprises a plurality of temperature sensors. The temperature sensors can be arranged directly in sections of the temperature control system and / or in the areas of the machine tool to be temperature-controlled in order to obtain information regarding the current temperature of the areas to be temperature-controlled. Preferably, all temperature sensors are connected to the control unit of the temperature control system. The control unit is configured to set the target temperature of each temperature control circuit based on the temperature values ​​recorded by the temperature sensors.

[0016] More preferably, the heat source is a heating cartridge. The heating cartridge is preferably equipped with an electrical power supply and enables rapid adjustment of the temperature control fluid. The heating cartridge is preferably integrated into the machine tool or a separately installed temperature control device. More preferably, the cooling source is an internal cooling machine in the machine tool or the separately installed temperature control device. Alternatively, the cooling source is an external cooling source. This can, for example, also be a cooling unit installed in the ambient air outside the machine hall in which the machine tool with the temperature control system according to the invention is arranged.

[0017] More preferably, the liquid-to-air heat exchanger is an air temperature control unit or a recirculation unit. Air temperature control units can be designed as simple passive water-to-air heat exchangers, in which air is blown through the heat exchanger through which the temperature control fluid flows, using a fan or the like. Recirculation units can be used, for example, in a hood or housing of the machine tool, particularly if no sealing air function is required or no extraction from the cavity area of ​​the machine tool to be temperature-controlled is necessary. This can save energy.

[0018] Further preferably, the control unit of the temperature control system is configured such that the areas to be temperature-controlled by means of the liquid-air heat exchanger are temperature-controlled first. Only then are the areas to be temperature-controlled by direct temperature control via a temperature control circuit temperature-controlled. This may be necessary because temperature control, for example of a machine bed or other areas of the machine tool that are temperature-controlled directly with the temperature-control fluid, reaches the desired temperature considerably more quickly through heat conduction than when temperature control is carried out using air, for example in a working area of ​​the machine tool. For energy reasons, it is therefore advantageous to give priority to the temperature control of the areas to be temperature-controlled via the liquid-air heat exchanger. The direct temperature control circuits can particularly preferably be shut off using an additional shut-off valve.

[0019] According to a further preferred embodiment of the invention, the control unit is configured to operate the heat source precisely such that the temperature of the temperature control fluid exiting the heat source corresponds exactly to the highest target temperature of a temperature control circuit of the temperature control system. Additionally or alternatively, the control unit is further configured to operate the cold source such that the temperature of the temperature control fluid exiting the cold source corresponds exactly to the lowest target temperature of a temperature control circuit. This clever measure also enables significant energy savings in the temperature control system.

[0020] Further preferably, the control unit of the temperature control system is configured to switch off the heat source when the temperature control fluid supplied to the heat source has a temperature which is greater than or equal to the highest target temperature of one of the temperature control circuits.

[0021] Preferably, the control unit is further configured to shut off the cooling source when the temperature control fluid supplied to the cooling source has a temperature that is less than or equal to the lowest target temperature of one of the temperature control circuits. This measure can also enable energy-efficient operation of the temperature control system.

[0022] Further preferably, the pump is a speed-controlled pump. This allows different flow requirements for the tempering fluid to be met during different operating times of the machine tool. Alternatively, a secondary pump connected in parallel to the pump can be provided to meet different flow requirements for the tempering fluid.

[0023] The temperature control system according to the invention is preferably integrated into the machine tool. However, it is also possible for the temperature control system to be arranged as a separate unit outside a housing of the machine tool, with only lines for the temperature control circuits leading into and out of the machine tool.

[0024] A preferred embodiment of the invention will be described in detail below with reference to the accompanying drawings. In the drawing: Fig. 1 a schematic representation of a machine tool with a tempering system according to a preferred embodiment of the invention, and Fig. 2 a schematic sectional view of the machine tool of Fig. 1 with different temperature control circuits only partially shown.

[0025] The following is based on the Fig. 1 and Fig. 2 a machine tool 1 with a tempering system 2 is described in detail.

[0026] The temperature control system 2 is designed to control the temperature of various areas or components of the machine tool.

[0027] As in Fig. 2, these areas or components can be, for example, a machine bed 100, a Z-column 101, a hood 102, a drive housing 103 or a drive, a Z-axis with spindle 104 or a working area 106.

[0028] Each area of ​​the machine tool 1 is tempered by a separate tempering circuit.

[0029] The temperature control system 2 comprises a tank 3 and a pump 4 (cf. Fig. 1). A secondary pump 44 can be connected in parallel to pump 4, which is the main pump.

[0030] The pump 4 or the auxiliary pump 44 are configured to pump a temperature control fluid from the tank 3. The temperature control fluid 3 can be water or oil or an emulsion or another liquid.

[0031] As particularly in Fig. As shown in Figure 1, a temperature control circuit is provided for each area to be temperature-controlled. A first temperature control circuit 10 is provided for the temperature control of the Z-column 101. A second temperature control circuit 20 is provided for the temperature control of the machine bed 100. A third temperature control circuit 30 is provided for the temperature control of the working area 106. A fourth temperature control circuit 40 is provided for the temperature control of a drive housing 103. A fifth temperature control circuit 50 is provided for the temperature control of grinding oil or a cooling lubricant.

[0032] The temperature control system 2 further comprises a heat source 6 and a cold source 7. As can be seen from Fig. As can be seen in Figure 1, the tank 3 is connected to an inlet 60 of the heat source 6. The tank 3 is also connected to an inlet 70 of the cold source 7. A supply line 110 is divided at a branch 111 so that the tempering fluid supplied by the pump can be supplied to both the heat source 6 and the cold source 7.

[0033] As from Fig. As can be seen in Figure 1, a mixing valve is provided in each temperature control circuit. More specifically, a first mixing valve 11 is provided in the first temperature control circuit 10, a second mixing valve 21 in the second temperature control circuit 20, a third mixing valve 31 in the third temperature control circuit 30, a fourth mixing valve 41 in the fourth temperature control circuit 40, and a fifth mixing valve 51 in the fifth temperature control circuit 50.

[0034] How to continue Fig. As can be seen in Figure 1, starting from an outlet 61 of the heat source, the line for the temperature control circuits is branched in such a way that the outlet 61 of the heat source 6 is connected to a mixing valve 11, 21, 31, 41, 51. In the same way, an outlet 71 of the cold source 7 is also connected by several branches to a mixing valve 11, 21, 31, 41, 51 (cf. Fig. 1).

[0035] Thus, each mixing valve has a first inlet 81 connected to the heat source, a second inlet 82 connected to the cold source and an outlet 83 connected to one of the temperature control circuits 10, 20, 30, 40, 50.

[0036] The temperature control system 2 further comprises a control unit 8, which is shown schematically in Fig. 1. The control unit 8 is configured to set a predetermined target temperature for each of the temperature control circuits 10, 20, 30, 40, 50 by means of the mixing valves 11, 21, 31, 41, 51. Depending on the desired target temperature, an inflow from the heat source 6 and / or the cold source 7 is increased or decreased or completely interrupted. The mixing valves can also be completely shut off, so that neither heated nor cooled temperature control fluid can be supplied to a temperature control circuit. For reasons of clarity, Fig. 1 the connections between the control unit 8 and the respective mixing valves are not shown.

[0037] How to continue Fig. As can be seen in Figure 1, each mixing valve 11, 21, 31, 41, 51 in the respective temperature control circuit 10, 20, 30, 40, 50 is followed by a temperature sensor 9. The temperature sensors 9 detect the temperature in the respective temperature control circuit. The temperature sensors 9 are also connected to the control unit 8, which controls the mixing valves accordingly based on the detected temperatures in the respective temperature control circuits. For reasons of clarity, Fig. 1 also does not show the connections between the temperature sensors 9 and the control unit 8.

[0038] How further from the Fig. 1 and Fig. 2, the first temperature control circuit 10 is designed as a direct temperature control circuit. This means that the first temperature control circuit 10 is introduced directly into the area of ​​the machine tool to be temperature controlled, in this embodiment, the Z-column 101. A heat exchanger 12 is directly integrated into the Z-column 101. This eliminates the need for further heat transfer to another circuit.

[0039] The further temperature control circuits 20, 30, 40, 50 are constructed such that a liquid-air heat exchanger is arranged in each of these temperature control circuits. More precisely, a first liquid-air heat exchanger 22 is arranged in the second temperature control circuit 20. A second liquid-air heat exchanger 32 is arranged in the third temperature control circuit 30. A third liquid-air heat exchanger 42 is arranged in the fourth temperature control circuit 40. A fourth liquid-air heat exchanger 52 is arranged in the fifth temperature control circuit 50 (see FIG. Fig. 2).

[0040] The four liquid-air heat exchangers 22, 32, 42, 52 can now temper areas of the machine tool 1 using air. This is shown schematically in Fig. 2 shown.

[0041] The second liquid-air heat exchanger 32 is used to provide sealing air 107 in the area of ​​the Z-axis with spindle 104. This is shown schematically in Fig. 2. The sealing air can be used, for example, to deflect chips or to redirect oil mist in the working area 106 of the machine tool.

[0042] The reference numeral 105 refers to a bellows which enables axial movements of the Z-axis with spindle 104 and in particular protects the components arranged in the drive housing 103 from contamination.

[0043] Advantageously, the control unit 8 is configured such that temperature control of the machine bed 100 or other areas of the machine tool that are directly temperature controlled by heat conduction only occurs after the areas of the machine tool have been temperature controlled by means of the liquid-air heat exchangers 22, 32, 42, 52. This is due to the fact that, due to heat conduction, temperature adjustment occurs considerably faster with direct temperature control than with temperature control via air, for example in the work area. Therefore, for energy reasons, it is advisable to first supply the liquid-air heat exchangers with the temperature control fluid to prepare the machine tool for operation and thus temperature control the air-temperature-controlled areas of the machine tool.Only at a later point in time can the areas of the machine tool that require direct temperature control be tempered. Therefore, it is possible that, as shown in . Fig. 1, for example, the first temperature control circuit 10 can be completely shut off by means of an additional shut-off valve 108.

[0044] How to continue in Fig. 1, all temperature control circuits 10, 20, 30, 40, 50 lead back to tank 3.

[0045] The number of temperature control circuits is chosen only as an example. There are at least two, but there can be more than the five circuits shown.

[0046] Furthermore, it is also possible for the temperature control system 2 to be operated by the control unit 8 in such a way that, when the temperature of the temperature control fluid in the tank 3 corresponds to the warmest required target temperature in one of the temperature control circuits, the mixing valve for this temperature control circuit is set such that it only allows 100% of the temperature control fluid from the line in which the heat source 6 is located to pass through. The heat source 6 can, of course, be switched off in this case, since no additional heat supply is necessary, as the temperature of the temperature control fluid corresponds exactly to the highest target temperature.

[0047] For machine tools that transfer a relatively large amount of heat to the temperature control fluid, so that the temperature control fluid in tank 3 is maintained at a relatively high temperature, a heat source 6 in the temperature control system 2 can be dispensed with. The temperature control fluid flows from branch 111 directly to the first inlet of the mixing valve 81 of the mixing valves 11, 21, 31, 41, and 51.

[0048] Alternatively or additionally, a heat source 6 can be arranged in the tank 3 in order to heat the tempering fluid to a temperature, e.g. before machining on the machine tool, which corresponds to the warmest required target temperature in one of the tempering circuits.

[0049] The same applies to the cold branch of the temperature control system 2 if the temperature of the temperature control fluid supplied to the cold source 7 from tank 3 corresponds to the coldest temperature in the temperature control system. Accordingly, the cold source 7 can of course also be shut down in such an operating situation. List of reference symbols 1 machine tool 2 Tempering system 3 tanks 4 Pump 6 Heat source 7 Cold source 8 Control unit 9 Temperature sensor 10 first temperature control circuit 11 first mixing valve 12 heat exchangers 20 second temperature control circuit 21 second mixing valve 22 first liquid-air heat exchanger 30 third temperature control circuit 31 third mixing valve 32 second liquid-air heat exchanger 40 fourth temperature control circuit 41 fourth mixing valve 42 third liquid-air heat exchanger 44 Auxiliary pump 50 fifth temperature control circuit 51 fifth mixing valve 52 fourth liquid-air heat exchanger 60 Heat source inlet 61 Heat source outlet 70 Inlet of the cold source 71 Outlet of the cold source 81 first inlet of the mixing valve 82 second inlet of the mixing valve 83 Mixing valve outlet 100 machine bed 101 Z-pillar 102 Hood / Housing 103 Drive housing 104 Z-axis with spindle 105 Bellows 106 Workspace 107 Sealing air 108 Shut-off valve 110 supply line 111 Junction

Claims

[1] Machine tool with a tempering system (2) arranged for tempering different areas of the machine tool, the tempering system (2) comprising: - a tank (3) filled with a tempering fluid, - a pump (4) for pumping the tempering fluid from the tank (3), - a temperature control circuit (10, 20, 30, 40, 50) for each area of ​​the machine tool to be temperature controlled, each temperature control circuit returning to the tank (3), - a branch (111), the branch (111) being connected to the pump (4), - a cold source (7), wherein the branch (111) is connected to an inlet (70) of the cold source (7), - wherein a mixing valve (11, 21, 31, 41, 51) is arranged in each temperature control circuit (10, 20, 30, 40, 50), wherein each mixing valve has a first inlet (81) connected to the branch (111), a second inlet (82) connected to the cold source (7) and an outlet (83) leading to the temperature control circuit, and - a control unit (8) which is designed to set a predetermined target temperature of each temperature control circuit by means of the mixing valves (11, 21, 31, 41, 51). [2] Machine tool according to claim 1, wherein a heat source (6) is arranged between the branch (111) and the first inlets of the mixing valves (81), which heat source is designed to heat the tempering fluid supplied to the inlets of the mixing valves (81). [3] Machine tool according to claim 1 or 2, wherein a heat source (6) is arranged in the tank (3) and is arranged to heat the temperature fluid in the tank (3). [4] Machine tool according to one of the preceding claims, wherein at least one temperature control circuit (10) directly controls the temperature of a region of the machine tool. [5] Machine tool according to one of the preceding claims, wherein at least one temperature control circuit (11, 21, 31, 41, 51) has a liquid-air heat exchanger (22, 32, 42, 52) in order to temperature control a region of the machine tool by means of air. [6] Machine tool according to claim 5, wherein the area of ​​the machine tool to be tempered with air is a working area (106) of the machine tool. [7] Machine tool according to claim 5 or 6, wherein the tempered air from the liquid-air heat exchanger is a sealing air (107) at a region of the machine tool. [8] Machine tool according to one of the preceding claims, further comprising a plurality of temperature sensors (9), wherein the temperature sensors (9) are arranged on the temperature control system (2) and / or on the area of ​​the machine tool to be temperature controlled. [9] Machine tool according to one of the preceding claims, wherein the heat source (6) is a heating cartridge and / or wherein the cold source (7) is an internal cold source of the machine tool or an external cold source. [10] Machine tool according to one of claims 5 to 9, wherein the liquid-air heat exchanger (22, 32, 42, 52) is an air temperature control device or a recirculating air device. [11] Machine tool according to one of claims 5 to 10, wherein the control unit (8) is arranged to firstly temper the areas to be tempered by means of the liquid-air heat exchangers (22, 32, 42, 52) and then subsequently to temper the areas to be tempered directly by a tempering circuit. [12] Machine tool according to one of the preceding claims, - wherein the control unit (8) is configured to operate the heat source (6) such that a temperature of the temperature control fluid emerging from the heat source (6) corresponds exactly to a highest target temperature of one of the temperature control circuits (10, 20, 30, 40, 50), and / or - wherein the control unit (8) is configured to operate the cold source such that a temperature of the tempering fluid emerging from the cold source (7) corresponds exactly to the lowest target temperature of a tempering circuit. [13] Machine tool according to one of the preceding claims, wherein the control unit (8) is arranged to switch off the heat source (6) when the tempering fluid supplied to the heat source (6) from the tank (3) has a temperature which is greater than or equal to the highest target temperature of one of the tempering circuits. [14] Machine tool according to one of the preceding claims, wherein the control unit (8) is arranged to switch off the cold source (7) when the tempering fluid supplied to the cold source (7) from the tank (3) has a temperature which is less than or equal to the lowest target temperature of one of the tempering circuits.

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