Device for applying viscous material to workpieces

Abstract

A device for applying viscous material to workpieces includes a rotary lance in a holder apparatus and rotatable about a longitudinally-extending rotation axis, the lance having at least one material outlet. A needle valve associated with each material outlet has a longitudinally-extending valve needle used to close each material outlet on a valve seat. Each valve needle has an associated cylinder with a plunger chamber in which a plunger is movable by pressure applied by a fluid, the valve needle being permanently connected to the plunger. A tappet is connected to each plunger, the tappet, at its upper end facing away from the at least one valve seat, being sealingly guided out of the associated plunger chamber. The rotary lance has a measuring element which can be acted upon by the tappet and moved longitudinally; and the holder apparatus has a sensor for determining the measuring element position.

Claims

1. An apparatus for applying a viscous material to workpieces, comprising: a holding device; a rotary lance arranged to rotate in the holding device about an axis of rotation that runs in a longitudinal direction, wherein the rotary lance comprises at least one material outlet, a needle valve assigned to the at least one material outlet, the needle valve comprising a valve needle extending in the longitudinal direction and configured to close off the at least one material outlet at a valve seat, a cylinder assigned to the valve needle, the cylinder comprising a piston chamber, a piston connected to the valve needle and movable by applying pressure in the piston chamber using a fluid, and a tappet connected with the piston and passed through out of the piston chamber at an end face of the piston chamber that faces away from the valve seat so as to seal off the piston chamber; and a measuring element configured to be displaced in the longitudinal direction by applying a force using the tappet; wherein the holding device has a sensor for determining a position of the measuring element.

2. The apparatus according to claim 1, wherein the rotary lance has a plurality of cylinders, a plurality of material outlets, and a plurality of needle valves, each needle valve of the plurality of needle valves being assigned to a respective material outlet of the plurality of material outlets and comprising a respective valve needle extending in the longitudinal direction and configured to close off the respective material outlet assigned to the needle valve at a respective valve seat, a respective cylinder assigned to the respective valve needle comprising a respective piston chamber, a respective piston connected to the respective valve needle and movable by applying pressure in the respective piston chamber using a fluid, and a respective tappet connected with the respective piston and passed through out of the respective piston chamber at an end face of the respective piston chamber that faces away from the respective valve seat so as to seal off the respective piston chamber.

3. The apparatus according to claim 2, wherein the plurality of cylinders are arranged at equal distances from one another and at equal distances from the axis of rotation.

4. The apparatus according to claim 1, wherein the measuring element has a permanent magnet and wherein the sensor is a magnetic sensor.

5. The apparatus according to claim 4, wherein the permanent magnet has the form of an axially poled circular ring that has a ring thickness and rotates about the axis of rotation, and wherein the axially poled circular ring has a radius at least 5 times as great as the ring thickness, measured in a radial direction.

6. The apparatus according to claim 5, wherein the radius is at least 8 times as great as the ring thickness, measured in the radial direction.

7. The apparatus according to claim 4, wherein the measuring element has a holding plate, wherein the force is applied to the holding plate using the tappet, and wherein the permanent magnet is fastened to the holding plate.

8. The apparatus according to claim 1, wherein the rotary lance has a housing composed of non-ferromagnetic material, in which the cylinder and the measuring element are accommodated.

9. The apparatus according to claim 8, wherein the measuring element is configured to receive a reset force applied to a first end of the measuring element in the direction of the cylinder, wherein the measuring element is moved against the reset force when the valve needle is lifted off the valve seat.

10. The apparatus according to claim 9, wherein the reset force is applied by at least one pressure spring that is arranged between the measuring element and a housing ceiling of the housing.

11. The apparatus according to claim 10, wherein at least one further pressure spring is assigned to the at least one spring and applies against a second end of the measuring element a further reset force less than and opposite to the reset force.

12. The apparatus according to claim 10, wherein the measuring element is guided by at least one guiding pin that extends in the longitudinal direction through the measuring element.

13. The apparatus according to claim 12, wherein the at least one guiding pin is arranged centered through the at least one pressure spring, and wherein the at least one pressure spring is configured as a helical spring.

14. The apparatus according to claim 1, wherein the tappet is connected off-center with the piston and is arranged closer to the axis of rotation than a longitudinal center axis of the piston.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the invention will be explained in greater detail using an exemplary embodiment shown schematically in the drawing. The figures show:

(2) FIG. 1 shows a perspective view of an apparatus for applying viscous material;

(3) FIG. 2a, 2b show a part of the apparatus according to FIG. 1 in section, in a side view and in a perspective view;

(4) FIG. 3 shows a front view of the apparatus shown in FIG. 1; and

(5) FIG. 4 shows a sectional view of the apparatus shown in FIG. 3 along the line B-B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) The apparatus 10 shown in the drawing serves for applying viscous material to workpieces, in the present exemplary embodiment for applying varnish. However, other uses are also conceivable, such as, for example, the application of adhesives, sealants, insulation material or heat-conducting paste. The application apparatus 10 has a holding device 12, which is intended to be mounted on a robot arm. A rotary lance 14 is mounted in the holding device 12, which lance can rotate about an axis of rotation with reference to the holding device 12, which axis extends in a longitudinal direction 16. At its lower end, the rotary lance 14 has three material outlets 18, from which viscous material can exit to be applied to a workpiece, from a housing 20 of the rotary lance 14 that is produced from aluminum, and at which outlets an application nozzle is generally mounted, in each instance. Three needle valves 22 are accommodated in the housing 20, wherein each needle valve 22 is assigned to one of the material outlets 18. The valve needles 24 of the needle valves 22 each close off one of the material outlets 18 at a valve seat 23, or release the material outlet 18 by means of lifting off from the valve seat 23. Each of the needle valves has a dual-action pneumatic cylinder 26 assigned to it, in the piston chamber 28 of which a piston 30 can be displaced back and forth in the longitudinal direction 16, with which piston the valve needle 24 in question, which also extends in the longitudinal direction 16, is firmly connected. A movement of the piston 30 by means of applying compressed air thereby results in a movement of the valve needle 24 and in opening or closing of the material outlet 18 in question at the valve seat 23. A closing spring 32, arranged in the piston chamber 28 and configured as a helical spring, presses the corresponding piston 30 downward and the valve needle 24 onto the related valve seat 23, so that the material outlets 18 are always closed when the compressed air is not in effect.

(7) The apparatus 10 is controlled in such a manner that only one material outlet 18 is always open at a time. In order to monitor whether one of the material outlets 18 is open or whether all the material outlets 18 are closed, the holding device 12 has a magnetic sensor 34 that is fixed in place. This sensor detects the position of a measuring element 36 that can move in the housing 20 of the rotary lance 14. The measuring element 36 has a holding plate 38 that can be displaced back and forth in the housing 20, in the longitudinal direction 16, and a ring-shaped permanent magnet 40 that is firmly connected with the holding plate 38. The holding plate 38 is guided on a central guiding pin 42 as well as on three outer guiding pins 44, wherein each of the guiding pins 42, 44 extends through an opening in the holding plate 38. A pressure spring 48, 50 supported at the top on a housing ceiling 46 and at the bottom on the holding plate 38 is arranged around each of the guiding pins 42, 44, which spring presses the measuring element 36 downward. In this regard, this involves a central pressure spring 48 arranged around the central guiding pin 42 and three outer pressure springs 50, each arranged around one of the outer guiding pins 44. A tappet 52 is firmly connected with each of the pistons 30, which tappet is passed out from the top of the piston chamber 28 in question, which top faces away from the valve seats 23 and faces the measuring element, and the tappet lies against the holding plate 38. If one of the material outlets 18 is opened by means of raising the piston 30 in question, the tappet 52 connected with this piston 30 presses the measuring element 46 upward, so that the magnetic sensor 34 can detect the movement of the permanent magnet 40. The magnetic sensor 34 then generates a valve open signal. If the material outlet 18 is closed again by means of lowering the piston 30 in question, the pressure springs 48, 50 bring about lowering of the measuring element 36, which is detected by the magnetic sensor 34, which generates a valves closed signal.

(8) The cylinders 26 are arranged next to one another in the sense that their cross-sections, which are made perpendicular to the longitudinal direction 16, do not overlap. Impacting of the measuring element 36 by means of the tappets 52 therefore cannot take place centrally, in other words in the center of the holding plate 38. In order to prevent tilting of the measuring element 36 in the housing 20, the tappets 52 are arranged off-center on the piston 30 and offset as far as possible in the direction toward the center of the holding plate 38 or in the direction of the center longitudinal axis of the rotary lance 14. Furthermore, a further, weaker pressure spring 48, 50 lies opposite each of the pressure springs 48, 50, the former pressing against the holding plate 38 from below. In this regard, the pressure springs 48, 50 and the further pressure springs 48, 50 are dimensioned in such a manner that each pair, consisting of one of the pressure springs 48, 50 and the opposite further pressure spring 48, 50, exerts a force on the holding plate 38, in total, that is directed downward, in other words in the direction toward the cylinders 26.

(9) In the exemplary embodiment shown, the rotary lance 14 has three needle valves 22. It is obviously understood that the rotary lance 14 can be equipped with one, two or more than three needle valves 32.

(10) In summary, the following should be stated:

(11) The invention relates to an apparatus 10 for applying viscous material to workpieces, having a rotary lance 14 arranged to rotate about an axis of rotation that runs in a longitudinal direction 16, in a holding device 12, which lance has at least one material outlet 18, wherein a needle valve 22 is assigned to each material outlet 18, by means of the valve needle 24 of which, extending in the longitudinal direction 16, the corresponding material outlet 18 can be closed off at a valve seat 23, and wherein a cylinder 26 is assigned to each valve needle 24, in the piston chamber 28 of which cylinder a piston 30 can be moved by means of a fluid, by applying pressure, with which piston the valve needle 24 is firmly connected. According to the invention, it is provided that a tappet 52 is connected with each piston 30, which tappet is passed out of the piston chamber 28 in question, in a sealed-off manner, on the top that faces away from the at least one valve seat 23, that the rotary lance 14 has a measuring element 36 that can be impacted by means of the tappets 52 and displaced in the longitudinal direction 16, and that the holding device 12 has a sensor 34 for determining the position of the measuring element 36.