Device for conveying viscous material

Abstract

A device (12) for conveying viscous material to an applicator (14) with a conveying cylinder (16) in which a double-acting conveying piston (18) can be moved to and fro, wherein the conveying cylinder (16) has a first and a second chamber (20, 22) which are separated from one another by the conveying piston (18), wherein each of the chambers (20, 22) has a material inlet (24, 26) and a material outlet (38, 40), with a conveying device (30) which is connected to the material inlets (24, 26) for the pressurized introduction of viscous material into the chambers (20, 22) of the conveying cylinder (16), and with a valve device (44) for closing and opening the material inlets (24, 26) and the material outlets (38, 40). It is provided according to the invention that, in a first switching position, the valve device (44) opens the material inlet (24) of the first chamber (20) and the material outlet (40) of the second chamber (22) and closes the material inlet (26) of the second chamber (22) and the material outlet (38) of the first chamber (20) and, in a second switching position, releases the material inlet (26) of the second chamber (22) and the material outlet (38) of the first chamber (20) and closes the material inlet (24) of the first chamber (20) and the material outlet (40) of the second chamber (22).

Description

[0001] Device for conveying viscous material

[0002] The invention relates to a device for conveying viscous material to an applicator according to the preamble of claim 1 and to a control device according to the preamble of claim 10, which is preferably used with the device.

[0003] Such devices are typically used in industrial manufacturing, particularly in the automotive industry, where workpieces are coated with viscous materials, such as adhesives, sealants, insulation materials, TIM materials, or thermal paste. They are used to convey the viscous material to an applicator, which then doses the viscous material and applies it to the respective workpiece. Such devices are often large and very heavy, yet continuous conveyance of the viscous material is often inadequate. Furthermore, conventional devices of the type mentioned above often do not allow for active pressure control.

[0004] It is therefore an object of the invention to further develop a device and an applicator of the type mentioned at the outset in such a way that the above-mentioned disadvantages are at least partially largely avoided.

[0005] This object is achieved according to the invention by a device having the features of claim 1 and by a control device having the features of claim 10 and claim 16, respectively. Advantageous developments of the invention are the subject of the dependent claims.

[0006] The conveying device according to the invention is based on the idea of ​​displacing the material in the other chamber by pressurizing the filling of one chamber of the conveying cylinder and conveying it to the applicator through the material outlets leading directly or indirectly to the applicator. As soon as the latter chamber is emptied, the principle is reversed, and the emptied chamber is pressurized and filled with the viscous material, displacing the material from the former chamber and conveying it to the applicator. This method enables almost continuous conveying while minimizing downtime.

[0007] It is preferred that the valve device comprises a valve housing and a slide that can be moved back and forth within the valve housing, wherein the valve housing and the slide define a closable and openable passageway for each of the material inlet openings and for each of the material outlet openings. In the first switching position of the valve device, the slide opens the passageways of the material inlet of the first chamber and the material outlet of the second chamber and closes the passageways of the material inlet of the second chamber and the material outlet of the first chamber. In the second switching position of the valve device, the slide opens the passageways of the material inlet of the second chamber and the material outlet of the first chamber and closes the passageways of the material inlet of the first chamber and the material outlet of the second chamber.With the slide, only one movable component needs to be provided and moved during operation, so that the device can be built smaller and lighter than conventional devices. Controlling the valve device is also simpler than with conventional devices of the type mentioned above, since in principle only the slide needs to be moved back and forth between its positions defining the two switching positions of the valve device. The slide is preferably cylindrical in shape, in particular in the shape of a circular cylinder, i.e. it has a circular cross-section which promotes smooth displacement. Furthermore, it is preferred that the valve device has a sleeve inserted into the valve housing, into which sleeve the slide is precisely inserted.The precise insertion of the slide into the sleeve results in a satisfactory seal, so that additional sealing elements between the slide and the sleeve can be dispensed with if necessary. Such sealing elements, in particular elastomeric sealing rings, are expediently inserted between the sleeve and the housing and seal the passageways against one another. Since the sleeve is immovably housed in the valve housing, the sealing rings are not subject to movement-related wear. The valve housing is also expediently made of several parts, with several housing sections placed axially next to one another and preferably firmly connected. This measure facilitates assembly, in particular the insertion of the sealing rings between the valve housing and the sleeve when assembling the valve device.

[0008] A displacement sensor is advantageously provided for detecting the position of the delivery piston in the delivery cylinder. The displacement sensor can be a mechanical sensor that measures the movement of a piston rod protruding from the delivery cylinder. However, it is preferred that the displacement sensor has a permanent magnetic element firmly connected to the delivery piston and a magnetostrictive element firmly connected to the delivery cylinder. An evaluation unit is provided that evaluates the magnetostriction induced by the permanent magnetic element in the magnetostrictive element. With this design, no piston rod needs to be led out of the delivery cylinder under complex sealing, and the position of the delivery piston in the delivery cylinder can be measured with high accuracy.The measurement of the position of the feed piston in the feed cylinder is advantageously used to control the valve device and / or a feed pump of the feed device in order to dose the viscous material before it is fed to the applicator. For this purpose, a control unit is expediently provided, which receives position data from the displacement sensor and, depending on the position data, controls the valve device and / or the feed pump in order to achieve the most continuous material flow possible. In particular, the displacement sensor can detect when one of the chambers is almost completely empty, so that the control unit can control the valve device to move it into a different switching position by moving the slide.

[0009] It can further be provided that the valve device at least partially opens both material outlets and / or both material inlets in at least one intermediate position. In particular, one of the material outlets is then already opened while the other material outlet is not yet completely closed, thus further minimizing downtime.

[0010] The control device according to the invention, as defined in claim 10, is based on the idea of ​​enabling the control valve to open and close precisely and with high temporal resolution by providing an actuator to actuate the closing element. Since conventional actuators can often apply either a large force but only a small stroke, or a small force but a large stroke, a force transmission element is provided, which is connected to the closing element at a connection point and is acted upon by the actuator at a loading point.

[0011] According to an advantageous embodiment, the force transmission element is a lever that is mounted in or on the housing so that it can pivot about a pivot axis. The actuator can be a piezo actuator, which can apply a large force but only a small stroke. In order to increase the stroke of the closing element, the application point is then closer to the pivot axis than the connection point, whereby the distance of the connection point is preferably at least five times and more preferably at least eight times as great as the distance of the application point from the pivot axis. The lever can be single-armed or double-armed. In the latter case, the connection point is arranged at or near the free end of the longer lever arm, while the application point is arranged on the shorter lever arm.If the lever is single-armed, the connection point is located at or near the free end of the lever arm, while the application point is located on the same lever arm near the pivot axis.

[0012] According to another possible design, the actuator has a voice coil, which can generate a large stroke but only a small force. To increase the force acting on the locking element, the connection point is then located closer to the pivot axis than the actuation point, with the distance of the actuation point preferably being at least five times, and more preferably at least eight times, the distance of the connection point from the pivot axis. In this case, the lever can also be single-armed or double-armed, although the double-armed design is preferred.

[0013] According to an advantageous embodiment, the force transmission element is a hydraulic element and the actuator is a piezo actuator. By appropriately sizing the hydraulic element at the connection point and at the application point, the large force applied by the piezo actuator can be converted into a sufficient stroke on the closing element.

[0014] Alternatively or in addition to this measure according to the invention, a pressure sensor for measuring the pressure of the viscous material can be arranged in the material line of the control device. The pressure sensor is expediently arranged downstream of the valve seat and thus measures the pressure of the viscous material flowing out of the control valve. Based on this pressure measurement, the pressure of the viscous material can be adjusted to a target value. For this purpose, the pressure sensor is preferably connected to a control unit that adjusts the pressure of the viscous material at the pressure sensor to the target value by controlling the actuator depending on the pressure measured by the pressure sensor.

[0015] The control device according to the invention preferably forms, with the device according to the invention for conveying viscous material and an applicator having a nozzle with at least one outlet opening for the viscous material, a device for applying viscous material to workpieces, in which the material outlets of the device for conveying viscous material are connected on the inlet side to the material line of the control device, and in which the material line is connected on the outlet side to the applicator. According to a preferred method, this device is operated such that the control unit for controlling the actuator regulates the pressure of the viscous material at the pressure sensor to a desired value depending on the pressure measured by the pressure sensor.In addition or as an alternative to the above-mentioned method step, the control unit controls the valve device and / or the feed pump to achieve a continuous material flow. If a multi-component material is to be applied, a device according to the invention for conveying viscous material and a control device according to the invention are provided for each of the components. The material outlets of the device for conveying viscous material are connected on the inlet side to the material line of the control device, and the material lines are connected on the outlet side to a common applicator, which also has a mixer for mixing the components.

[0016] The invention will be explained in more detail below with reference to an embodiment shown schematically in the drawing.

[0017] Fig. 1 is a schematic representation of a device for applying viscous material;

[0018] Fig. 2a, 2b a schematic representation of a device for conveying viscous material as a component of the device according to Fig. 1 and a part of a valve device in a sectional representation in a first and a second switching position;

[0019] Fig. 3 is a partial view of the device according to Fig. 2a, 2b in section and

[0020] Fig. 4 shows a sectional view of a control device of the device according to Fig. 1. The device 10 shown in the drawing for applying a viscous material to workpieces, referred to as application device 10 for short, comprises a device 12 for conveying the viscous material, referred to as conveying device 12 for short, an applicator 14 to which the conveying device 12 conveys the viscous material and which applies the viscous material to the workpieces, and a control device 15 which controls the material flow from the conveying device 12 to the applicator 14 and / or the material pressure. Unlike the illustration shown in the drawing, the control device 15 and the applicator 14 can also be integrated together into a housing and form a single assembly.

[0021] The application device 10 shown in the drawing is used for applying a single-component viscous material to workpieces. If a multi-component material is to be applied to workpieces, a corresponding application device would be equipped with a number of conveyor devices 12 and control devices 15 corresponding to the number of components, each of which feeds one of the components to a common applicator 14, which then also includes a mixer for mixing the components.

[0022] The conveying device 12 has a conveying cylinder 16 in which a conveying piston 18 can move back and forth. The conveying piston 18 divides the interior of the conveying cylinder 16 into a first chamber 20 and a second chamber 22, which is sealed from the second chamber by the conveying piston 18 and which can each be varied in size due to the mobility of the conveying piston 18. The first chamber 20 has a first material inlet 24, while the second chamber 22 has a second material inlet 26. Both material inlets 24, 26 are connected via a conveying line 28 to a conveying device 30, which has a conveying pump 32 and a pressure regulator 34. The conveying pump 32 provides the energy potential for the application device 10. A first pressure sensor 36 for measuring the pressure of the viscous material is arranged in each of the chambers 20, 22.The first chamber 20 also has a first material outlet 38, while the second chamber 22 has a second material outlet 40, wherein a supply line 42 leads from the material outlets 38, 40 via the control device 15 to the applicator 14.

[0023] By moving the feed piston 18, viscous material can be displaced from the chamber 20, 22, which shrinks as a result of the movement of the feed piston 18, so that this material can be conveyed from the respective material outlet 38, 40 into the supply line 42. Such a movement of the feed piston 18 is achieved in the present case by introducing the viscous material into the other chamber 20, 22 under pressure. For this purpose, a valve device 44 is provided which, in a first switching position (Fig. 2a), opens the first material inlet 24 and blocks the second material inlet 26 and simultaneously closes the first material outlet 38 and opens the second material outlet 40. In a second switching position (Fig. 2b), this principle is reversed, and the valve device 44 releases the second material inlet 26 and the first material outlet 38 and blocks the first material inlet 24 and the second material outlet 40.In this way, pressurized viscous material is always introduced into one of the chambers 20, 22 via the respective material inlet 24, 26, interrupted at most by short dead times, and the viscous material located in the other chamber 20, 22 is conveyed through the associated material outlet 38, 40 into the feed line 42 and thus to the applicator 14.

[0024] Contrary to the schematic representation in Fig. 1, 2a, 2b, the material inlets 24, 26 and the material outlets 38, 40 are not arranged on different sides of the conveyor cylinder 16, but on one side, or the corresponding lines extend to one side, so that the valve device 44 can be designed according to the sectional views in Fig. 2a, 2b, 3. The valve device 44 has a valve housing 46, only shown in Fig. 3, in which a slide 48 is guided so that it can be moved back and forth. As can also be seen from the detailed representation in Fig. 3, a sleeve 50 is inserted between the valve housing 46 and the slide 48, which sleeve is also shown in Fig. 2a, 2b, and which is immovably received in the valve housing 46 and in which the slide 48 is received so that it can be moved with a precise fit.The valve housing 46, the slide 48, and the sleeve 50 define a passage 52 for each of the material inlets 24, 26 and for each of the material outlets 38, 40, which passage can be blocked or opened by appropriately positioning the slide 48 in the valve housing 46 and in the sleeve 50. In the first switching position of the valve device 44 according to Fig. 2a, the passages 52 of the first material inlet 24 and the second material outlet 40 are opened, while the passages 52 of the second material inlet 26 and the first material outlet 38 are closed. In the second switching position of the valve device 44 according to Fig. 2b, however, the passage channels 52 of the second material inlet 26 and the first material outlet 38 are opened, while the passage channels 52 of the first material inlet 24 and the second material outlet 40 are closed.

[0025] While the slide 48 is already sufficiently sealed due to its precise insertion into the sleeve 50, five sealing rings 54 are inserted between the sleeve 50 and the valve housing 46, sealing the passages 52 from each other and from the environment. The valve housing 46 is composed of several housing parts, which are joined together in an axial direction and firmly connected to one another, as not shown in detail in the drawing. The sleeve 50 is a two-part construction with two sleeve parts joined together in the axial direction, while the slide 48 is a single piece with a circular cross-section.

[0026] The delivery device 12 also has a displacement sensor 56 with which the position of the delivery piston 18 relative to the delivery cylinder 16 can be determined. The delivery piston 18 is guided on a piston rod 58 that runs centrally axially through the delivery cylinder 16 and axially penetrates the delivery piston 18. The delivery piston 18 is provided with a permanent magnetic element 60, while the piston rod 58 has a magnetostrictive element 62 in which the permanent magnetic element 60 induces magnetostriction. An evaluation unit 64 is also provided, which evaluates the induced magnetostriction and transmits data to a control unit (not shown in detail). The displacement sensor 56 can, for example, detect when one of the chambers 20, 22 is empty, so that the control unit can control the valve device 44 to move it to a different switching position.In addition, the displacement sensor 56 can measure a speed of the conveying piston 18 in the conveying cylinder 16, so that the control unit can also control the flow of the conveyed material.

[0027] The control device 15 according to the invention (Fig. 4) has a housing 70 through which a material line 72, connected to the supply line 42, extends to the applicator 14. The applicator 14 has a nozzle 74 with an outlet opening 76 for the viscous material. It can also have a closing valve that gives it an on-off function or that is controllable or adjustable. Also arranged in the housing 70 is a control valve 78, the closing element 80 of which, in the form of a valve needle, can close and open the material line 72 at a valve seat 82. Also arranged in the housing 70 is an actuator 84, designed as a piezo actuator in the illustrated embodiment, which acts at an application point 86 on a lever 88 that can pivot about a pivot axis 90 fixed to the housing.The lever 88 is a single-armed lever, and facing away from the application point 86, a return spring 92 designed as a compression spring acts on the lever 88, against whose restoring force the piezo actuator 84 can pivot the lever 88. The application point 86 is arranged very close to the pivot axis 90. Significantly further away from the pivot axis 90, near the free end of the lever 88, there is a connection point 94 at which the lever 88 is connected to the closing element 80. When the piezo actuator 84 applies pressure to the lever 88 against the force of the return spring 92, the closing element 80 is lifted off the valve seat 82, while the return spring 92 pushes the closing element 80 back onto the valve seat 82 by applying pressure to the lever 88 when the force of the piezo actuator 84 is removed.A second pressure sensor 96 is arranged in the material line 72 downstream of the valve seat 82. This second pressure sensor measures the pressure at which the viscous material exits the control valve 78. The measured pressure values ​​are fed to a control device 98, which, depending on the measured pressure values ​​measured by the second pressure sensor 96, regulates the pressure of the viscous material to a predetermined setpoint by controlling the piezo actuator 84 by opening the control valve 78 further or less widely.

[0028] In summary, the invention relates to a device 12 for conveying viscous material to an applicator 14 with a conveying cylinder 16 in which a double-acting conveying piston 18 is movable back and forth, wherein the conveying cylinder 16 has a first and a second chamber 20, 22 which are separated from one another by the conveying piston 18, wherein each of the chambers 20, 22 has a material inlet 24, 26 and a material outlet 38, 40, with a conveying device 30 connected to the material inlets 24, 26 for pressurized introduction of viscous material into the chambers 20, 22 of the conveying cylinder 16 and with a valve device 44 for closing and opening the material inlets 24, 26 and the material outlets 38, 40.According to the invention, it is provided that the valve device 44, in a first switching position, releases the material inlet 24 of the first chamber 20 and the material outlet 40 of the second chamber 22 and closes the material inlet 26 of the second chamber 22 and the material outlet 38 of the first chamber 20, and in a second switching position, releases the material inlet 26 of the second chamber 22 and the material outlet 38 of the first chamber 20 and closes the material inlet 24 of the first chamber 20 and the material outlet 40 of the second chamber 22.

Claims

Claims Device for conveying viscous material to an applicator (14) with a conveying cylinder (16) in which a double-acting conveying piston (18) is movable back and forth, wherein the conveying cylinder (16) has a first and a second chamber (20, 22) which are separated from one another by the conveying piston (18), wherein each of the chambers (20, 22) has a material inlet (24, 26) and a material outlet (38, 40), with a conveying device (30) connected to the material inlets (24, 26) for pressurized introduction of viscous material into the chambers (20, 22) of the conveying cylinder (16) and with a valve device (44) for closing and opening the material inlets (24, 26) and the material outlets (38, 40), characterized,that the valve device (44) in a first switching position releases the material inlet (24) of the first chamber (20) and the material outlet (40) of the second chamber (22) and closes the material inlet (26) of the second chamber (22) and the material outlet (38) of the first chamber (20) and in a second switching position releases the material inlet (26) of the second chamber (22) and the material outlet (38) of the first chamber (20) and closes the material inlet (24) of the first chamber (20) and the material outlet (40) of the second chamber (22). Device according to claim 1, characterized in that the valve device (44) has a valve housing (46) and a slide (48) which is movable back and forth in the valve housing (46), wherein the valve housing (46) and the slide (48) for each of the material inlet openings (24, 26) and for each of the material outlet openings (38, 40) have a closable and freely, define a pass-through channel (52), and that in the first switching position of the valve device (44) the slide (48) opens the pass-through channels (52) of the material inlet (24) of the first chamber (20) and the material outlet (40) of the second chamber (22) and closes the pass-through channels (52) of the material inlet (26) of the second chamber (22) and the material outlet (38) of the first chamber (20) and in the second switching position of the valve device (44) opens the pass-through channels (52) of the material inlet (26) of the second chamber (22) and the material outlet (38) of the first chamber (20) and closes the pass-through channels (52) of the material inlet (24) of the first chamber (20) and the material outlet (40) of the second chamber (22).

3. Device according to claim 2, characterized in that the slide (48) has a cylindrical shape and in particular the shape of a circular cylinder.

4. Device according to claim 2 or 3, characterized in that the valve housing (46) is multi-part with several housing parts attached to one another in the axial direction.

5. Device according to one of claims 2 to 4, characterized in that the valve device (44) has a sleeve (50) inserted into the valve housing (46), into which the slide (48) is inserted with a precise fit.

6. Device according to one of the preceding claims, characterized by a displacement sensor (56) for detecting the position of the delivery piston (18) in the delivery cylinder (16).

7. Device according to claim 6, characterized in that the displacement sensor (56) comprises a permanent magnetic element (60) firmly connected to the feed piston (18), a magnetostrictive element (62) firmly connected to the feed cylinder (16) and an evaluation unit (64) for Evaluation of the magnetostriction induced by the permanent magnetic element (60) in the magnetostrictive element (62).

8. Device according to claim 6 or 7, characterized by a control unit which controls the valve device (44) and / or a feed pump (32) of the feed device (30) in dependence on position data received from the displacement sensor (56).

9. Device according to one of the preceding claims, characterized in that the valve device (44) at least partially releases both material outlets (38, 40) and / or both material inlets (24, 26) in at least one intermediate position.

10. Control device for controlling the flow and / or pressure of a viscous material, comprising a housing (70), a material line (72) running through the housing (70), a control valve (78) arranged in the housing (70) for closing the material line (72) by placing a closing element (80) on a valve seat (82) and for releasing the material line (72) by lifting the closing element (80) off the valve seat (82), and an actuator (84) arranged in the housing (70) for actuating the closing element (80), characterized by a force transmission element which is connected to the closing element (80) at a connection point (94), the actuator (84) acting on the force transmission element at an actuation point (86).

11. Control device according to claim 10, characterized in that the force transmission element is a lever (88) which is mounted in or on the housing (70) so as to be pivotable about a pivot axis (90).

12. Control device according to claim 11, characterized in that the actuator (84) is a piezo actuator and that the application point (86) is closer to the pivot axis (90) than the connection point (94). Control device according to claim 11, characterized in that the actuator (84) has a plunger coil, and that the connection point (94) is closer to the pivot axis (90) than the loading point (86). Control device according to claim 10, characterized in that the force transmission element is a hydraulic element, and that the actuator (84) is a piezoelectric actuator. Control device according to one of claims 10 to 14, characterized in that a pressure sensor (96) for measuring the pressure of the viscous material is arranged in the material line (72).A control device for controlling the flow and / or pressure of a viscous material, comprising a housing (70), a material line (72) extending through the housing (70), a control valve (78) for closing the material line (72) by placing a closing element (80) on a valve seat (82) and for releasing the material line (72) by lifting the closing element (80) from the valve seat (82), and an actuator (84) for actuating the closing element (80). A control device according to claim 15 or 16, characterized in that the pressure sensor (96) is arranged downstream of the valve seat (82).Control device according to one of claims 15 to 17, characterized by a control unit (98) which is connected to the pressure sensor (96) and which, by controlling the actuator (84) as a function of the pressure measured by the pressure sensor (96), regulates the pressure of the viscous material at the pressure sensor (96) to a desired value.

19. Device for applying viscous material to workpieces with a device (12) according to one of claims 1 to 9, with a control device (15) according to one of claims 10 to 18 and with an applicator (14) which has a nozzle (74) having at least one outlet opening (76) for the viscous material.

20. A method for applying viscous material to workpieces using a control device (15) according to claim 18, wherein the control unit (98) regulates the pressure of the viscous material at the pressure sensor (96) to a desired value by controlling the actuator (84) as a function of the pressure measured by the pressure sensor (96).

21. A method for applying viscous material according to claim 20 using a device (10) according to claim 19, wherein the control unit controls the valve device (44) and / or the feed pump (32) to achieve a continuous material flow.

22. A method for conveying viscous material using a device (12) according to claim 8 or 9, wherein the control unit controls the valve device (44) and / or the feed pump (32) to achieve a continuous material flow.

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