DEVICE AND METHOD FOR COOLING WORKPIECES

Abstract

The invention relates to a device for cooling workpieces. The device has at least one nozzle which is configured to blow a fluid onto a workpiece. At least one surface temperature sensor is able to be arranged on the workpiece. In order to cool the workpiece, it is blown with a fluid by means of the at least one nozzle, the temperature of said fluid being lower than the surface temperature of the workpiece. In the process, the surface temperature is monitored by means of the at least one surface temperature sensor.

Claims

1. Device for cooling workpieces having at least one nozzle which is configured to blow a fluid onto a workpiece, and at least one surface temperature sensor which is able to be arranged on the workpiece.

2. Device according to claim 1, characterized in that the device is arranged in an air-conditioned room.

3. Device according to claim 2, characterized in that the nozzle is configured to take air as fluid from the room.

4. Device according to claim 2, characterized in that the nozzle is configured to take air as fluid from a cold-air source of the room.

5. Device according to claim 2, characterized in that the room is an air-conditioning tunnel, which connects a production facility for the workpiece to an analysis system for the workpiece.

6. Device according to claim 5, characterized in that the analysis system is a measuring unit.

7. Device according to claim 1, characterized in that the at least one surface temperature sensor is a surface contact temperature sensor.

8. Device according to claim 7, characterized in that the device has at least one movable arm which is configured to move the surface contact temperature sensor up to the workpiece.

9. Device according to claim 7, characterized in that the device has at least one data line which is configured to be connected to the surface contact temperature sensor which is arranged on the workpiece.

10. Method for cooling workpieces, in which a workpiece is blown with a fluid by means of at least one nozzle, the temperature of said fluid being lower than the surface temperature of the workpiece, and wherein the surface temperature is monitored by means of at least one surface temperature sensor.

11. Method according to claim 10, characterized in that the device is arranged in an air-conditioned room, wherein air is taken as fluid from the room.

12. Method according to claim 11, characterized in that the blowing of the workpiece is continued for a predeterminable period of time after the surface temperature thereof has reached the ambient temperature thereof.

13. Method according to claim 10, characterized in that the device is arranged in an air-conditioned room, wherein air is taken as fluid from a cold-air source of the room.

14. Method according to claim 13, characterized in that the blowing of the workpiece is continued until the surface temperature thereof has dropped below the ambient temperature thereof.

15. Method according to claim 10, characterized in that the workpiece is cooled in an air-conditioning tunnel and is subsequently transported onwards into an analysis system and analysed in the analysis system.

16. Method according to claim 15, characterized in that, during the analysis, at least one surface temperature sensor is used, which was also used for monitoring the surface temperature during the cooling of the workpiece.

17. Method according to claim 10, characterized in that the at least one nozzle and the at least one surface temperature sensor are parts of a device for cooling workpieces.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Exemplary embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

[0020] FIG. 1 shows a schematic side view of a device according to a first exemplary embodiment of the invention.

[0021] FIG. 2 shows a schematic side view of a device according to a second exemplary embodiment of the invention.

[0022] FIG. 3 shows a schematic side view of a device according to a third exemplary embodiment of the invention.

[0023] FIG. 4 shows a schematic side view of a device according to a fourth exemplary embodiment of the invention.

[0024] FIG. 5 shows a chart of cooling times of workpieces in a conventional cooling operation and according to various exemplary embodiments of the method according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] A device for cooling workpieces according to a first exemplary embodiment of the invention is illustrated in FIG. 1. A production facility 1, which is embodied as a machining centre, has a passage into an air-conditioned room 2 which is in the form of an air-conditioning tunnel. Via a ceiling inlet 21, air cooled to 17° C. by a cold-air source 22 is passed into the air-conditioned room 2 in order to lower the internal temperature thereof to a predetermined value of 20° C. The air-conditioned room 2 is connected to a likewise air-conditioned analysis system 3 which in the present case contains a coordinate measuring machine. The device 4 is arranged in the air-conditioned room 2. A conveyor belt 11 can transport workpieces 5 from the production facility 1, through the air-conditioned room 2 and into the analysis system 3. In this case, the workpieces 5 are at a temperature in the range of 55° C. to 60° C. when they leave the production facility 1. Before they are transported onwards into the analysis system 3, they are cooled to 20° C. in the air-conditioned room 2.

[0026] The device 4 has two nozzles 411, 412. Air is drawn in from the air-conditioned room 2 through an intake opening 421. A workpiece 5 is blown with this air at a temperature of 20° C. by means of the nozzles 411, 412. A surface temperature sensor 43, which is embodied as a contact temperature sensor, is already fastened to the surface of the workpiece 5 in the production facility 1. It is connected to the device 4 by means of a data line 44 in the air-conditioned room 2. The nozzles 411, 412 blow the workpiece 5 with air until the surface temperature sensor 43 measures a surface temperature of 20° C. for a predetermined period of time. This predetermined period of time was calculated empirically for the workpiece 5. Then, the data line 44 is removed and the workpiece is transported onwards into the analysis system 3 for measurement. During measurement, the surface temperature of the workpiece is again determined by means of the surface temperature sensor 43, which to this end is connected to the coordinate measuring machine. If deviations from the desired dimensions are determined in the process, a machine tool in the production facility can be adapted in order to avoid the deviations when the next workpieces are produced.

[0027] A device 4 for cooling workpieces according to a second exemplary embodiment of the invention is illustrated in FIG. 2. It differs from the device 4 according to the first exemplary embodiment in that it has a connection line 422 to the cold-air source 22. The nozzles 411, 412 can be supplied with air either by means of the intake opening 421 or by means of the connection line 422. The cooling operation differs from the cooling operation in the first exemplary embodiment in that the surface of the workpiece 5 is first of all cooled to a temperature of 17° C. with air from the connection line 422. Subsequently, the workpiece is blown again with air at a temperature of 20° C. from the intake opening 421, until the surface of the workpiece 5 has reached a temperature of 20° C. Then, blowing is interrupted without further delay, the data line 44 is removed and the workpiece is transported onwards into the analysis system 3 for measurement.

[0028] A device 4 for cooling workpieces according to a third exemplary embodiment of the invention is illustrated in FIG. 3. It differs from the device 4 according to the first exemplary embodiment in that it has two surface temperature sensors 431, 432. These are not already attached to the workpiece 5 in the production facility 1. They also do not remain on the workpiece 5 after the air-conditioned room 2 has been left. Rather, each surface temperature sensor 431, 432 is arranged at the end of an arm 441, 442. By means of the arms 441, 442, the surface temperature sensors 431, 432 are moved up to different positions on the surface of the workpiece 5 before blowing is started. After blowing is finished, they are removed from the workpiece 5 again by means of the arms 441, 442.

[0029] As illustrated in FIG. 4, in a fourth exemplary embodiment of the invention, a connection line 422 between the device 4 and the cold-air source 22 can also be provided when the surface temperature sensors 431, 432 of the third exemplary embodiment are used.

[0030] FIG. 5 illustrates a bar chart showing how long it takes for an aluminium cylinder head leaving the production facility 1 as workpiece 5 at a temperature of 60° C. to be cooled to a temperature of 20° C. given different volumetric flow rates of the blowing. In a comparative example, in which blowing is omitted, the cooling lasts for a period t of 7 hours and 58 minutes. Illustrated alongside is how blowing with air at a temperature of 20° C. and a volumetric flow rate of 500 m.sup.3/h, 700 m.sup.3/h and 1000 m.sup.3/h by means of a device according to the first or the third exemplary embodiment shortens the cooling time. In this case, a volumetric flow rate of 500 m.sup.3/h corresponds to a blowing speed of 0.3 m/sec, a volumetric flow rate of 700 m.sup.3/h corresponds to a blowing speed of 0.5 m/sec and a volumetric flow rate of 1000 m.sup.3/h corresponds to a blowing speed of 1.0 m/sec. How long it takes until the surface temperature of 20° C. is reached for the first time is specified in each case. Further blowing over the empirically calculated predetermined period is not contained in the specified period t. Further shortening of the cooling time can be achieved in that, by means of a device according to the second or fourth exemplary embodiment, first of all blowing with air at a temperature of 17° C. and then further blowing with air at a temperature of 20° C. takes place. This is illustrated by hatched bars in FIG. 5. How long it takes until the surface temperature of 20° C. is reached for the first time is specified in each case here, too. Further blowing with air at a temperature of 20° C. is not contained in the specified period t. It can be seen that, by means of the devices according to the first or third exemplary embodiment, the cooling time can be shortened considerably. Even more pronounced shortening of the cooling time takes place by means of a device according to the second or fourth exemplary embodiment, in that the workpiece 5 is first of all cooled to below the desired target temperature in order subsequently to be warmed up thereto.