Round dryer

Abstract

A round dryer for drying workpieces has a helically revolving workpiece passage in a work container and is provided with a heating device. The work container is closed at its upper side.

Claims

1. A round dryer for drying workpieces, said round dryer comprising: a work container having an upper side, the work container being closed at its upper side and in which work container the workpieces pass through a helical workpiece passage in a conveying direction; a closed heating air circuit with a heating device that sucks air out of the work container, heats and dehumidifies the work container, with the heating device configured to return the heated and dehumidified air having a maximum temperature of 75° C. into the work container; and a closed circulating air circuit with at least one circulating air blower, a circulating air suction that is provided in the region of a container base and a circulating air supply that is provided at a peripheral wall of the work container.

2. The apparatus in accordance with claim 1, wherein the work container has a thermal insulation.

3. The apparatus in accordance with claim 1, wherein an outer side of the work container reaches a maximum temperature of 40° C. in operation.

4. The apparatus in accordance with claim 1, wherein at least one hot air supply is provided at a base of the work container.

5. The apparatus in accordance with claim 4, wherein two diametrically oppositely disposed hot air supplies are provided at the base of the work container.

6. The apparatus in accordance with claim 1, wherein at least one hot air outlet is provided at the upper side of the work container.

7. The apparatus in accordance with claim 6, wherein at least two diametrically oppositely disposed hot air outlets are provided at the upper side of the work container.

8. The apparatus in accordance with claim 4, wherein at least one hot air outlet is provided at the upper side of the work container and the hot air supply and the hot air outlet are arranged offset from one another in a plan view.

9. The apparatus in accordance with claim 1, wherein a conveying direction and a flow direction of the hot air extend transversely to one another.

10. The apparatus in accordance with claim 1, wherein the circulating air blower generates an air flow that extends in counter-flow to the conveying direction.

11. The apparatus in accordance with claim 1, wherein the circulating air supply is configured to blow circulating air at least approximately tangentially into the workpiece passage.

12. The apparatus in accordance with claim 1, wherein a base of the workpiece passage is at least partly permeable to air.

13. The apparatus in accordance with claim 12, wherein the base of the workpiece passage has wire mesh.

14. The apparatus in accordance with claim 1, wherein a base of the workpiece passage is coated with plastic.

15. The apparatus in accordance with claim 1, wherein the workpiece passage has a pre-drying zone in which a blow-off device is provided.

16. The apparatus in accordance with claim 1, wherein the workpiece passage has a step section.

Description

(1) The present invention will be described in the following purely by way of example with reference to an advantageous embodiment and to the enclosed drawings. There are shown:

(2) FIG. 1: a perspective view of a round dryer with a heating device;

(3) FIG. 2: a plan view of the arrangement of FIG. 1; and

(4) FIG. 3: a side view of the arrangement of FIG. 1.

(5) The Figures show a round dryer 10 for drying workpieces that has a generally cylindrical work container 12 in which a helically revolving workpiece passage (not shown) is provided. Workpieces to be dried are introduced through a workpiece inlet 14, provided at the outer wall of the work container, into the work container 12 or at the start of its workpiece passage. Due to the vibration of the resiliently supported work container 12 with the aid of at least one unbalance motor, the workpieces then reach a workpiece outlet 16 at the lower side of the outer wall of the work container 12. In the embodiment shown, the workpiece passage itself is formed from a wire mesh that is coated with polyurethane and that helically revolves around the inner periphery of the work container via approximately two and a half revolutions over a distance of approximately 9.5 m. However, it is understood that the length and the width of the workpiece passage and its coating are variable. A workpiece supply can also take place through the upper side or a cover of the work container.

(6) As the Figures illustrate, the work container 12 is completely closed at its upper side, which is achieved in the embodiment shown by a cover 18 that is screwed to the container wall in a thermally sealing manner. Alternatively, the cover can also be formed in one piece with the container wall.

(7) Furthermore, the round dryer 10 shown in the Figures has a heating device 20 in which heated and dehumidified air having a maximum temperature of 70° C. is provided. This dehumidified air is guided from the heating device 20 via two air hoses 22 and 23 provided with a thermal insulation and via thermally insulated pipes to a respective hot air supply at the base 13 (FIG. 3) of the work container 12. In this respect, the two hot air supplies are arranged diametrically oppositely disposed at the base 13 of the work container 12.

(8) After the introduction into the work container 12, the supplied, heated, and dehumidified air flows in a vertical direction through said work container 12 from the bottom to the top, which is facilitated by the air-permeable design of the workpiece passage. For the suction of the hot air that has flowed through the work container 12, two diametrically oppositely disposed hot air outlets 24 and 26 are provided at the upper side 15 of the work container 12 and are in turn connected to the heating device 20 via air hoses 28 and 29 provided with a thermal insulation and via thermally insulated pipes, whereby a closed air circuit is provided. For a good flowing through within the work container 12, the hot air supplies and the hot air outlets are arranged offset from one another, viewed in a plan view, and are in particular distributed uniformly over the periphery.

(9) To increase the air input into the work container 12, an optional circulating air blower 30 is provided in the embodiment shown that sucks in air from the base 13 (FIG. 3) of the work container 12 via an air hose 31 and blows it into the work container 12 in counter-flow to the conveying direction of the workpieces. For this purpose, a circulating air supply 32, by which the circulating air can be blown at least approximately tangentially into the workpiece passage, is provided at the peripheral wall of the work container 12. The circulating air supply 32 is located approximately at the center of the work container, i.e. at half the height, so that warm hot air, which has been sucked in from the base of the work container, is introduced into the upper region of the work container in counter-flow. A second closed air circuit is thus provided by the circulating air blower 30.

(10) The reference numeral 36 designates an electric switch cabinet. In this switch cabinet, a control for the round dryer can be provided by which, among other things, the rotational speed of the unbalance motors can be controlled, the amplitude of the vibration of the work container can be measured, and the preparation of the air guided through the work container can be regulated. The temperature of the workpieces in the workpiece passage can be measured contactlessly and a monitoring device can be provided that outputs a signal if no more workpieces are located in the workpiece passage. It can hereby be avoided that different batches are accidentally mixed. Furthermore, a separation device that prevents hot air from escaping from the work container 12 can be provided in the region of the workpiece inlet 14 and/or in the region of the workpiece outlet 16. Such a separation device can, for example, comprise a curtain or individual flaps composed of plastic or rubber or the like.