Device for applying a viscous material

Abstract

The invention relates to a device (10) for applying a viscous material to workpieces, comprising an application tube (16) having a material inlet opening (18) at a first end (20) and a material outlet opening (24) at a second end (26), defining an application channel (14), and being flexible at least over part of its length, and comprising a housing (12) for receiving the application tube (16), wherein the application tube (16) is connected to the housing (12) in an initial region (30) extending from the material inlet opening (18) and is arranged at a distance from the housing (12) in an end region (32) extending towards the material outlet opening (24), and wherein a bearing section (48) of the end region (32) is mounted near the material outlet opening (24) in a motor-driven eccentric (50) rotatable about a longitudinal central axis (46).and with an adjustment mechanism (100) for adjusting the distance of the bearing section (48) to the longitudinal center axis (46) between a minimum first distance and a maximum second distance.

Description

[0001] The invention relates to a device for applying a viscous material to workpieces according to the preamble of claim 1.

[0002] Such a device is known, for example, from EP 3 204 166 B1. In this device, which is used, for example, for applying viscous materials such as adhesives, sealants, insulating materials, or thermal pastes to workpieces such as car body components, an application tube, from whose material outlet the viscous material is applied to the workpiece, is mounted near its end in an eccentric. During the application process, the eccentric is rotated about its longitudinal axis, forcing a circular motion on the eccentrically mounted application tube at its tip, which contains the material outlet. This circular motion, often occurring at several thousand revolutions per minute, exerts centrifugal forces on the viscous material, resulting in a spiral movement of the material jet.This results in a circular material application and a width of the applied material strand that is significantly larger than the diameter of the material outlet opening. For this purpose, the application tube must be elastically flexible over at least part of its length. The known device also features an adjustment mechanism for changing the distance of the bearing section of the application tube, mounted in the eccentric, to the longitudinal center axis between a minimum distance (which can be zero) and a maximum distance, thus allowing the width of the applied material strand to be varied. If the eccentricity is zero, the width of the material strand is approximately equal to or slightly larger than the diameter of the material outlet opening, while at maximum eccentricity, the width of the material strand can be significantly increased. By adjusting the eccentricity, the width of the material strand can be varied between these two extremes.

[0003] According to DE 10 2004 062 063 A1, an electromagnet can be used to adjust the eccentricity. However, this method is complex and limits the choice of material for the application tube. For this reason, it has been proposed to use pneumatic cylinders to adjust the eccentricity, but these require a large installation space.

[0004] Another device for applying a viscous material to workpieces, the application tube of which can be set into an adjustable circular motion at its tip by means of an adjustable eccentric, is known from KR 10 2 017 596 B1.

[0005] The invention is therefore based on the objective of further developing a device of the type mentioned at the outset in such a way that it has a simpler structure.

[0006] This problem is solved according to the invention by a device having the features of claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

[0007] The invention is based on the idea of ​​arranging the first and second stop surfaces, which limit the displacement of the second piston, on a single component, the stop element, thus reducing the device's overall size. The design of the pneumatic cylinder with the first and second pistons, as well as the three pressure chambers defined by the two pistons, allows for the setting of minimum and maximum eccentricity, as well as an intermediate position with medium eccentricity. It is preferred that the stop element be formed in one piece and that it be fixed to the housing. Preferably, the first and second stop surfaces face away from each other.

[0008] Advantageously, the first stop surface is arranged in the second pressure chamber. This measure also contributes to a shorter device design. Furthermore, it is preferred that the second stop surface, to limit the displacement of the second piston, interacts with a counter surface that can be fixed in different positions relative to the second piston. In this way, the intermediate position with a medium eccentricity can be varied, allowing the medium eccentricity to be larger or smaller. For this purpose, a piston rod with the counter surface is advantageously screwed into the second piston. By adjusting the screw connection, the piston rod can be positioned in different positions relative to the second piston. It is also preferred that the stop element be a sleeve in which the piston rod is slidably guided.This measure allows the intermediate position with the medium eccentricity to be reliably set.

[0009] Advantageously, the first piston is displaceable away from the second piston up to a third stop surface and towards the second piston up to its stop. It is preferred that the third stop surface is located in the first pressure chamber, allowing for a compact device design. Advantageously, the third stop surface is movable relative to the housing in a longitudinal direction parallel to the longitudinal center axis and can be fixed in different positions. This allows the minimum eccentricity to be set and varied from zero.

[0010] Advantageously, the second piston for the second pressure chamber has a larger piston area than the first piston for the first pressure chamber. If both the second and first pressure chambers are then pressurized with compressed air at the same pressure, a greater force acts on the second piston than on the first piston, and the second piston pushes the first piston towards the connecting element as soon as it comes into contact with it.

[0011] It is preferred that the eccentric has an outer body rotatable about the longitudinal center axis by means of the motor drive and an inner body fixedly mounted in the outer body, in which the bearing section is mounted. The eccentricity is then expediently changed by the fact that the inner body is displaceable relative to the longitudinal center axis by means of the connecting element, thus adjusting the distance of the bearing section from the longitudinal center axis. For this purpose, it is preferred that the eccentric has a guide track for guiding the inner body within the outer body, which has at least one guide rib engaging in a guide groove, wherein the at least one guide groove and the at least one guide rib are inclined relative to the longitudinal center axis. It is preferred that the at least one guide rib is arranged on the outer body and the at least one guide groove on the inner body.To reduce friction, it is advantageous to mount the bearing section in the inner body by means of a rotary bearing.

[0012] The invention will now be explained in more detail with reference to an exemplary embodiment shown schematically in the drawing. The drawing shows... Fig. 1 a device for applying a viscous material in longitudinal section without an adjustment mechanism; Fig. 2 an adjustment mechanism for the device according to Fig. 1 in longitudinal section and Fig. 3 the eccentric of the device according to Fig. 1.

[0013] The device 10 shown in the drawing is used to apply a viscous material, for example an adhesive, to a workpiece. It has a housing 12 in which an application tube 16 is received, the tube surrounding an application channel 14 for the viscous material. The application tube 16 is multi-sectioned and extends from a first end 20, which has a material inlet opening 18, to a second end 26, which is formed by an application nozzle 22 with a material outlet opening 24. The viscous material is fed to the material inlet opening 18 via a material feed port 28 in the housing 12. The application tube 16 has a starting section 30 extending from the first end 20, which is connected to the housing 12, and an end section 32 extending to the second end 26, which is spaced apart from the housing 12 and is surrounded by an annular gap 34 over most of its length.The initial section 30 is partially formed by a first pipe section 36, to which a projection 38 is attached. In the other direction, an elastically flexible steel pipe 40 extends from the first pipe section 36, carrying the application nozzle 22 at its end. In the section belonging to the initial section 30, the steel pipe 40 is held in a guide sleeve 42, which is rotationally fixed within the housing 12. In a transition section 44 located between the initial section 30 and the end section 32, the distance between the guide sleeve 42 and the steel pipe 40 increases continuously until the annular gap 34 reaches its full width. The initial section 30 also defines a longitudinal center axis 46 running centrally through it.

[0014] The application tube 16 has a bearing section 48 in its end region 32, which is mounted in an eccentric 50 rotatably arranged about the longitudinal center axis 46 in the housing 12 and which is driven by a motor. The eccentric 50 has an outer body 52 in which an inner body 54 is received off-center, in which the bearing section 48 is in turn mounted by means of a rotary bearing 56 designed as a ball bearing.

[0015] The bearing section 48 can be moved between a minimally eccentric position and a maximally eccentric position, whereby the steel tube 40 is bent. In the minimally eccentric position, the bearing section 48 can have an eccentricity of zero, so that the longitudinal center axis 46 also forms the center axis of the end region 32. The greater the resulting eccentricity of the bearing section 48, determined by the outer body 52 and the inner body 54, the more the center axis of the end region 32 is bent. The greatest deviation from the longitudinal center axis 46 is located at the material outlet opening 24.Rotation of the eccentric 50 about the longitudinal central axis 46 by applying an electric motor 64 at a typical speed of several thousand revolutions per minute causes the material outlet opening 24 to move in a circular path, depending on the set eccentricity of the bearing section 48. This causes the viscous material exiting the opening to be swirled due to centrifugal forces and distributed over a significantly wider area than would be the case without rotation of the eccentric 50 or with an eccentricity of zero for the bearing section 48. The circular movement of the viscous material, and thus the application width, is greater the larger the resulting eccentricity of the bearing section 48.

[0016] To reliably introduce the viscous material into the application channel 14 via the material supply connection 28, the application tube 16 is provided with a circumferential annular groove 72 in the area of ​​the material supply connection 28, which extends a certain distance in the axial direction. The annular groove 72 opens into a transverse bore 74, which leads to the material inlet opening 18.

[0017] In Fig. Figure 2 shows an adjustment mechanism 100, which serves to move the inner body 54 relative to the outer body 52 in order to adjust the eccentricity of the bearing section 48. The adjustment mechanism 100 has a pneumatic cylinder 102 in which a first piston 104 and a second piston 106 are each slidably mounted. The first piston 104 is rigidly connected to the extension 38 by means of a connecting element 108 in the form of a rod extending from the pneumatic cylinder 102, so that a movement of the first piston 104 is transmitted to the extension 38 and thus to the application tube 16 and the inner body 54. On the side of the first piston 104 facing the connecting element 108 there is a first pressure chamber 110, while on the side of the second piston 106 facing away from the first piston 104 there is a second pressure chamber 112 and between the first piston 104 and the second piston 106 there is a third pressure chamber 114.The three pressure chambers 110, 112, and 114 can be pressurized with compressed air. The pneumatic cylinder 102 is rigidly connected to the housing 12. On the side of the pneumatic cylinder 102 facing away from the connecting element 108, a stop element 116 in the form of a sleeve is rigidly connected to it and thus also rigidly to the housing 12. The housing 12 has a first stop surface 118 located in the second pressure chamber 112 and a second stop surface 120 facing away from it. The first stop surface 118 limits the movement of the second piston 106 away from the first piston 104. A piston rod 122 is screwed into the second piston 106, which is led centrally through the stop element 116 out of the second pressure chamber 112 and has an annular counter surface 124 which faces the second stop surface 120 and comes into contact with the second stop surface 120 to limit the movement of the second piston 106 towards the first piston 104.On the side of the pneumatic cylinder 102 facing the connecting element 108, a further stop element 126 is arranged, which is also sleeve-shaped and extends through the connecting element 108. This further stop element 126 has a third stop surface 128, which is located in the first pressure chamber 110 and limits the movement of the first piston 104 away from the second piston 106. Furthermore, the first piston 104 is movable towards the second piston 106 until it comes into contact with it.

[0018] As in Fig. As shown in Figure 3, the inner body 54 is movable by means of the connecting element 108 to change the eccentricity of the bearing section 48 relative to the outer body 52. ​​For this purpose, a guide track 130 is provided, which has two diametrically opposed guide grooves 132 on the inner body 54 and two guide ribs 134 on the outer body 52, each engaging in one of the guide grooves 132. The guide grooves 132 and the guide ribs 134 are each inclined relative to the longitudinal center axis 46, so that when the inner body 54 is actuated via the connecting element 108 and the application tube 16, it is moved relative to the outer body 52 not only in the axial direction but also in the radial direction, thereby changing the eccentricity.

[0019] By pressurizing the pressure chambers 110, 112, and 114 with compressed air, three eccentricities of the bearing section 48 can be adjusted: a minimum eccentricity, a maximum eccentricity, and a medium eccentricity. The minimum eccentricity is set by introducing compressed air into the third pressure chamber 114, whereby the first piston 104 is pressed against the third stop surface 128 and the second piston 106 against the first stop surface 118. The minimum eccentricity is typically zero, meaning that the longitudinal center axis of the application tube 16 coincides with the longitudinal center axis 46 in the bearing section 48. However, the further stop element 126 is movable in a longitudinal direction parallel to the longitudinal center axis 46 with respect to the housing 12 and the pneumatic cylinder 102 and can be fixed in different positions, so that the third stop surface 128 can project further into the first pressure chamber 110 than in Fig.Figure 2 illustrates this. In this case, the minimum eccentricity is greater than zero. The maximum eccentricity is set by introducing compressed air into the first pressure chamber 110. The first piston 104 then moves towards the second piston 106 until it either comes into contact with it, preventing further movement of the first piston 104, or until the inner body 54 within the outer body 52 is blocked in the longitudinal direction by reaching an end position. The mean eccentricity is set by pressurizing both the first pressure chamber 110 and the second pressure chamber 112 with compressed air.The piston surface of the second piston 106 facing the second pressure chamber 112 is larger than the piston surface of the first piston 104 facing the first pressure chamber 110. Therefore, at the same pressure in the first pressure chamber 110 and the second pressure chamber 112, a greater force acts on the second piston 106 than on the first piston 104. The movement of the second piston 106 towards the first piston 104 is limited by the contact of the counter surface 124 with the second stop surface 120, thus determining the position of the second piston 106. The first piston 104 then moves towards the second piston 106 until it comes into contact with it. By rotating the piston rod 122 relative to the second piston 106, the position of the counter surface 124 relative to the second stop surface 120 is changed, and thus the mean eccentricity is altered.

[0020] The following clauses describe preferred embodiments of the invention which may define the invention as an alternative to the claims: 1. Device for applying a viscous material to workpieces, comprising an application tube (16) having a material inlet opening (18) at a first end (20) and a material outlet opening (24) at a second end (26), defining an application channel (14), and being flexible at least over part of its length, comprising a housing (12) receiving the application tube (16), wherein the application tube (16) is connected to the housing (12) in an initial region (30) extending from the material inlet opening (18) and is arranged at a distance from the housing (12) in an end region (32) extending towards the material outlet opening (24), and wherein a bearing section (48) of the end region (32) is mounted near the material outlet opening (24) in a motor-driven eccentric (50) rotatable about a longitudinal central axis (46).and with an adjusting mechanism (100) for adjusting the distance of the bearing section (48) to the longitudinal center axis (46) between a minimum first distance and a maximum second distance, characterized in that the adjusting mechanism (100) has a pneumatic cylinder (102) in which a first piston (104) connected to the eccentric (50) by means of a connecting element (108) and a second piston (106) are slidably received on the side of the first piston (104) facing away from the connecting element (108), and which has three pressure chambers (110, 112, 114) that can be pressurized with compressed air, wherein a first pressure chamber (110) is on the side of the first piston (104) facing the connecting element (108), a second pressure chamber (112) is on the side of the second piston (106) facing away from the first piston (104), and a third pressure chamber (114) is located between the is arranged between the first and second pistons (104, 106). 2. Device according to clause 1, characterized in that the adjusting mechanism (100) has a first and a second stop surface (118, 120), wherein the first stop surface (118) limits a displacement of the second piston (106) away from the first piston (104) and the second stop surface (120) limits a displacement of the second piston (106) towards the first piston (104). 3. Device according to clause 2, characterized in that the first and the second stop surfaces (118, 120) are facing away from each other. 4. Device according to clause 2 or 3, characterized in that the first stop surface (118) is arranged in the second pressure chamber (112). 5. Device according to one of clauses 2 to 4, characterized in that the second stop surface (120) to limit the displacement of the second piston (106) interacts with a counter surface (124) which can be fixed in different positions with respect to the second piston (106). 6. Device according to clause 5, characterized in that a piston rod (122) having the counter surface (124) is screwed into the second piston (106). 7. Device according to clause 6, characterized in that the second stop surface (120) is arranged on a sleeve in which the piston rod (122) is slidably guided. 8. Device according to one of clauses 2 to 7, characterized by a stop element (116) on which the first and the second stop surfaces (118, 120) are arranged. 9. Device according to clause 8, characterized in that the stop element (116) is formed in one piece. 10. Device according to clause 8 or 9, characterized in that the stop element (116) is fixedly mounted to the housing. 11. Device according to one of the preceding clauses, characterized in that the first piston (104) is displaceable away from the second piston (106) to a third stop surface (128) and towards the second piston (106) until it reaches a stop thereon. 12. Device according to clause 11, characterized in that the third stop surface (128) is arranged in the first pressure chamber (110). 13. Device according to clause 11 or 12, characterized in that the third stop surface (128) is movable relative to the housing (12) in a longitudinal direction parallel to the longitudinal center axis (46) and can be fixed in different positions. 14. Device according to one of the preceding clauses, characterized in that the second piston (106) to the second pressure chamber (112) has a larger piston area than the first piston (104) to the first pressure chamber (110). 15. Device according to one of the preceding clauses, characterized in that the eccentric (50) has an outer body (52) rotatable about the longitudinal central axis (46) by means of the motor drive and an inner body (54) fixedly mounted in the outer body (52), in which the bearing section (48) is mounted. 16. Device according to clause 15, characterized in that the inner body (54) is displaceable obliquely to the longitudinal center axis (46) by means of the connecting element (108) with respect to the outer body (52) in order to adjust the distance of the bearing section (48) to the longitudinal center axis (46). 17. Device according to clause 16, characterized in that the eccentric (50) has a guide track (130) for guiding the inner body (54) in the outer body (52), which has at least one guide rib (134) engaging in a guide groove (132), wherein the at least one guide groove (132) and the at least one guide rib (134) are inclined relative to the longitudinal center axis (46). 18. Device according to one of clauses 15 to 17, characterized in that the bearing section (48) is mounted in the inner body (54) by means of its rotary bearing (56).

Claims

[1] Device for applying a viscous material to workpieces, comprising an application tube (16) having a material inlet opening (18) at a first end (20) and a material outlet opening (24) at a second end (26), defining an application channel (14), and being flexible at least over part of its length, comprising a housing (12) receiving the application tube (16), wherein the application tube (16) is connected to the housing (12) in an initial region (30) extending from the material inlet opening (18) and is arranged at a distance from the housing (12) in an end region (32) extending towards the material outlet opening (24), and wherein a bearing section (48) of the end region (32) is mounted near the material outlet opening (24) in a motor-driven eccentric (50) rotatable about a longitudinal central axis (46),and with an adjustment mechanism (100) for adjusting the distance of the bearing section (48) to the longitudinal center axis (46) between a minimum first distance and a maximum second distance, , characterized by, that the adjusting mechanism (100) comprises a pneumatic cylinder (102) in which a first piston (104) connected to the eccentric (50) by means of a connecting element (108) and a second piston (106) are slidably received on the side of the first piston (104) facing away from the connecting element (108), and which has three pressure chambers (110, 112, 114) that can be pressurized with compressed air, wherein a first pressure chamber (110) is arranged on the side of the first piston (104) facing the connecting element (108), a second pressure chamber (112) is arranged on the side of the second piston (106) facing away from the first piston (104), and a third pressure chamber (114) is arranged between the first and the second pistons (104, 106), and that the adjusting mechanism (100) comprises a stop element (116) with a first and a second stop surface (118, 120) shows,wherein the first stop surface (118) limits a displacement of the second piston (106) away from the first piston (104) and the second stop surface (120) limits a displacement of the second piston (106) towards the first piston (104). [2] Device according to claim 1, characterized by , that the stop element (116) is formed in one piece. [3] Device according to claim 1 or 2, characterized by , that the stop element (116) is fixedly mounted to the housing. [4] Device according to any one of the preceding claims, characterized by , that the first and second stop surfaces (118, 120) are facing away from each other. [5] Device according to any of the preceding claims, characterized by , that the first stop surface (118) is arranged in the second pressure chamber (112). [6] Device according to one of the preceding claims, characterized by, that the second stop surface (120) to limit the displacement of the second piston (106) interacts with a counter surface (124) which can be fixed in different positions with respect to the second piston (106). [7] Device according to claim 6, characterized by , that a piston rod (122) having the counter surface (124) is screwed into the second piston (106). [8] Device according to claim 7, characterized by , that the stop element (116) is a sleeve in which the piston rod (122) is slidably guided. [9] Device according to any of the preceding claims, characterized by , that the first piston (104) is movable away from the second piston (106) to a third stop surface (128) and towards the second piston (106) until it reaches the stop on the latter. [10] Device according to claim 9, characterized by , that the third stop surface (128) is arranged in the first pressure chamber (110). [11] Device according to claim 9 or 10, characterized by , that the third stop surface (128) is movable relative to the housing (12) in a longitudinal direction parallel to the longitudinal center axis (46) and can be fixed in different positions. [12] Device according to any of the preceding claims, characterized by , that the second piston (106) to the second pressure chamber (112) has a larger piston area than the first piston (104) to the first pressure chamber (110). [13] Device according to any of the preceding claims, characterized by , that the eccentric (50) has an outer body (52) rotatable about the longitudinal central axis (46) by means of the motor drive and an inner body (54) fixedly mounted in the outer body (52), in which the bearing section (48) is mounted. [14] Device according to claim 13, characterized by, that the inner body (54) is displaceable obliquely to the longitudinal center axis (46) by means of the connecting element (108) with respect to the outer body (52) in order to adjust the distance of the bearing section (48) to the longitudinal center axis (46). [15] Device according to claim 14, characterized by , that the eccentric (50) has a guide track (130) for guiding the inner body (54) in the outer body (52), which has at least one guide rib (134) engaging in a guide groove (132), wherein the at least one guide groove (132) and the at least one guide rib (134) are inclined relative to the longitudinal center axis (46). [16] Device according to any one of claims 13 to 15, characterized by , that the bearing section (48) is supported in the inner body (54) by means of its rotary bearing (56).

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