Device and method for automated melting of an insert into a plastic component

Abstract

Device (1) with an insert (2) as a separate component for automated melting of the insert into a plastic component, comprising an adaptation surface for resting over the plastic component with a passage opening (5) for the insert, a gripping means (11) for positioning, aligning and fixing the insert in a specified position and axial alignment directly at the passage opening in the device, a pin (16) with a contact tip directed towards the specified position, a heat source (20) interacting with the pin, a temperature sensor on the contact tip and an axial guide with a linear feed drive (18) for the pin along the axial alignment, on which the pin can be moved between a retracted proximal pin position and an advanced distal pin position.

Description

[0001] The invention relates to a device and a method for the automated melting of an insert into a plastic component according to claims 1 and 9, respectively.

[0002] The invention is located in the field of process technology for the automated insertion of inserts, such as threaded inserts or bushings, as load-bearing elements into plastic components. Such plastic components are manufactured either using conventional manufacturing methods such as injection molding, machining, or forming processes such as deep-drawing or stretch-drawing, or using additive manufacturing processes (e.g., fused filament fabrication (FFF), resin-based stereolithography (SLA), or powder-based laser sintering (SLS). Additively manufactured components are particularly suitable for the production of components with complex geometries that cannot be achieved using conventional manufacturing processes.

[0003] The aforementioned inserts significantly expand the functional range of the components. They are used, in particular, to connect the component to other components, to attach component elements such as panels, or to electrically contact functionally integrated components.

[0004] By automating a process step, the economic efficiency and reliability of a production plant as well as the quality of the manufactured products can be significantly increased.

[0005] Based on this, one object of the invention is to propose a device and a method for an automated melting of the insert into a plastic component, in particular into additively manufactured plastic components.

[0006] The object is achieved with a device and a method for the automated melting of an insert into a plastic component having the features of claims 1 and 9, respectively. These dependent claims reflect advantageous embodiments and refinements of this solution.

[0007] To achieve this objective, a device with an insert as a separate component is proposed for the automated melting of the insert into a plastic component. The device comprises a combination of several sub-elements, a gripper finger, a melting device, and a heat source. The gripper finger comprises the components required for initially fixing the insert in the device and also relative to the plastic component. The melting device comprises all mechanical components required for immediately advancing the insert into the target position in the plastic component after the fixation in the device has been released, i.e. in particular feed devices and the guides required for this. The heat source, in turn, comprises the thermal means, including temperature control, required for melting when the insert is advanced into the target position in the plastic component.The insert is preferably a threaded insert, bushing, or other load-applying element, more preferably with a cylindrical outer contour. The device comprises the following components: . a) An adaptation surface to be placed over the plastic component with a through-opening for the use of: For this purpose, the device has a surface—the adaptation surface—with which it can be placed onto a support surface on the plastic component. The support is preferably flat or its topography is adapted to the support surface. One embodiment provides for a division of the adaptation surface into several, preferably three, partial surfaces (support elements), which preferably span a plane and compensate for any unevenness of the support surfaces. The passage opening is arranged entirely or predominantly in the adaptation surface; through this, the insert is inserted from the device into the plastic component. b) A gripping means for positioning, aligning and fixing the insert in a fixed position and axial alignment directly at the passage opening in the device: These gripping means are components of the aforementioned gripper finger sub-element. Since the alignment and position of the insert are important not only within the device but also relative to the plastic component, the gripper finger sub-element preferably also includes the aforementioned adaptation surface as a mechanical connection to the plastic component. In a preferred embodiment, the gripping means comprise two gripping jaws guided linearly against each other, which in turn are preferably movable in opposite directions synchronously via a common linear feed drive, preferably a pneumatic cylinder, and a respective wedge-thrust gear. The two gripping jaws move toward the insert on both sides and clamp it from two sides.The mechanical coupling of the two gripping jaws ensures that the gripped and secured inserts are centered in the predefined position within the device, advantageously independent of the cross-sectional dimensions, particularly the diameter of the insert. To ensure the alignment of the insert, at least one of the gripping jaws has a grooved alignment guide (alignment means) for the insert, in which the insert is guided along its outer surface. c) A pin with the contact tip directed to the specified position: The pin is used to push the insert from the aforementioned fixed position in the device into the target position in the plastic component after the gripping means have been released. It preferably has a cylindrical or other straight profile and is directed towards the insert in the aforementioned orientation. The insert preferably has a contact surface for the contact tip on the side facing the pin, wherein the contact surface and the contact tip simultaneously guide the insert on the pin in the axial orientation, i.e. the contact surface is at least partially designed as a negative form of the contact tip and thus enables surface contact between the pin and insert. If the contact tip is pushed onto the insert, surface contact is created, suitable for heat transfer between the pin and insert. d) A heat source interacting with the pen: The heat source heats the pin, which then transfers this heat to the insert via the contact tip through a flat solid-state contact, heating the insert to a temperature at least above the softening temperature of the plastic component. Preferably, the heat source and the pin are permanently connected to each other via a solid-state contact, with or without intermediate components acting as a thermal bridge. Alternative designs provide for contactless energy transfer means, for example, via inductive heat transfer. e) A temperature sensor at the contact tip: A temperature sensor, preferably a platinum resistance thermometer (e.g., PT 100), is used. This is used to measure the temperature heated by a heating element. An integrated or external PLC (programmable logic controller) with temperature control (PID controller) is used to maintain a specified target temperature. f) An axial guide with a linear feed drive for the pin along the axial alignment, on which the pin can be moved between a retracted proximal pin position and an advanced distal pin position: The axial guide serves to axially guide the pin and, once the contact tip hits the insert, also guides the pin for further advance. The linear feed drive preferably comprises a motorized linear drive oriented in the axial direction. Another preferred embodiment also provides positive torsion transmission elements as a guide, which impart not only a linear feed but also torsional moments, preferably around the pin's alignment. In this case, a torsion drive is preferably provided in addition to the linear feed drive for axial alignment.

[0008] To solve the problem, a method for the automated melting of an insert into a plastic component is also proposed. It comprises the following process steps: a) Provision of a device and an insert: The device, in its basic form and advantageous embodiments, is described within the scope of this application. As previously mentioned, it comprises an adaptation surface with a through-opening (hole or recess) through which the device can be placed on or above the surface of the plastic component. The through-opening can be positioned directly above the application site for insertion into the plastic component. The insert is then pushed through this through-opening from the device into the plastic component. For this purpose, the device comprises a gripping means for positioning, aligning, and securing the insert in a fixed position and axial alignment directly at the through-opening.Furthermore, the device comprises the previously described pin, which can be tempered by means of a heat source and is preferably heatable, with a contact tip directed towards the aforementioned fixed position, as well as an axial guide with a linear feed drive for the pin along the axial orientation, on which the pin can be moved between a retracted proximal pin position and an advanced distal pin position. b) Gripping and positioning the insert with the gripping means in a fixed position and axial alignment directly at the passage opening in the device: The insert is picked up, aligned, and secured in the device using the aforementioned gripper. For precise and reproducible alignment of the insert in the gripper jaws, these preferably have groove-shaped alignment means (e.g. grooves) in which the insert is also guided in a form-fitting manner (for frictional locking by the clamping itself). A form-fitting connection is created by blocking at least one relative degree of freedom of movement of two components using structural details (e.g. tongue and groove connections). A frictional connection differs from this in that in this case the task of fixing is not performed by structural details, but rather by pressing and thus a self-locking frictional connection (e.g. clamping). The aforementioned fixing of the insert in the gripper is preferably a hybrid of frictional and form-fitting.The fixation is achieved not only by the force-locking clamping, but preferably also by the optional form-locking alignment means. c) Placement of the device over the plastic component: As previously described, the device is positioned with the insert on or above the plastic component. d) Alignment of the insert with the device over a target cavity on the plastic component: This involves positioning the through-hole with the insert over the application site in the plastic component. The application site has a cavity, preferably open toward the through-hole—the target cavity—for later insertion of the insert. e) Heating the pin by means of the heat source until a target temperature at the contact tip is reached which is above the melting temperature of the plastic component, with the contact tip of the pin assuming a retracted proximal pin position. f) Moving the contact tip into axial alignment with the insert using the linear feed drive, with the insert guided on the contact tip. g) Heating the insert and releasing the gripping means from the insert. h) Moving the pin and insert by means of the linear feed drive towards the distal pin position, whereby the insert is pressed into the target cavity in the plastic component and melted: The target temperature in step e) should preferably be set high enough so that, after starting up according to step f), the insert is heated via the contact tip as a result of step g) such that, upon penetrating the plastic component or the target cavity, the plastic material contacted locally heats to a temperature preferably above the melting temperature, but at least above the softening temperature of the plastic (thermoplastic) used. Thus, after releasing the gripper means (step g), the heated insert can be pressed into the plastic component solely by positioning it on the contact tip and guided by the linear feed, and melted into the adjacent molten or softened plastic mass. i) Extending the contact tip from the insert and cooling the insert: Once the insert is pressed into the plastic component, the pin is retracted, preferably by the linear drive, thus breaking the heat-transferring contact between the insert and the contact tip. As a result, the insert cools down in the plastic component, preferably to a temperature at least below the softening temperature of the plastic. j) Removal of the device without inserting it into the plastic component.

[0009] The combination of gripping tool, heating element, and insertion device for use in a single device is advantageous. The invention thus enables fully automated insertion of threaded inserts, in particular, into individual plastic components, without manual tool retooling.

[0010] The invention is explained in more detail using an exemplary embodiment with the following figures and descriptions. All features and their combinations are not limited to this exemplary embodiment and its configuration. Rather, they are to be considered representative of other possible configurations that are not explicitly shown as exemplary embodiments. Fig. 1 a perspective view of an embodiment of a device with insert in a downwardly extended position, Fig. 2a and b side views of the embodiment according to Fig. 1, Fig. 3 a perspective partial sectional view of the embodiment according to Fig. 1 and Fig. 2a and b without linear feed drive, pin and insert, Fig. 4a and b a side view (a) and an exploded view (b) of the pin, the insert, a holder for the pin and a heat source as well as an axial guide with linear feed drive for the pin along the axial alignment according to Fig. 1 and Fig. 2a and b, Fig. 5 a perspective detailed view of the pin with its holder according to Fig. 1 and a heat source and Fig. 6a and b two sectional views of the gripping means for positioning, aligning and fixing the insert in a fixed position (a) as well as the axial guide with linear feed drive for the pin (b) for the Fig. 1 and Fig. 2a and b illustrated embodiment.

[0011] The Fig. 1 and Fig. 2a and b show an embodiment of the device 1 for the automated melting of an insert 2 into a plastic component (not shown). The insert is a separate component and is removed from the device after melting using the aforementioned method and replaced with a new insert.

[0012] The device 1 shown comprises a frame 3 composed of several components with a downwardly facing, preferably flat adaptation surface 4 for resting over the plastic component (not shown) with a through-opening 5 for an insert 2 to be applied into the component. In particular, the components of the frame in the exemplary embodiment comprise a suspension plate 6, a cover plate 7 with the aforementioned through-opening, jaw guide elements 8 arranged on both sides of the through-opening, a front plate 19 and a base plate 9 for receiving a pneumatic cylinder 10.The device further comprises a pin 16 with a heat source 20 interacting with it, with a temperature sensor 21, preferably at the contact tip 17 facing the insert, as well as an axial guide 22 with a linear feed drive 18 for the pin 16 along the axial alignment, on which the pin is movable between a retracted proximal pin position and an advanced distal pin position. The linear feed drive is attached to the base plate 9 in the device, and the axial guide is attached to the suspension plate 6. A guide arm 23 guides and fixes the pin 16 laterally on the linear feed drive above the through-opening 5.

[0013] Fig. 3 shows the device of the same embodiment in a partial sectional view, but without insert and without pin including the pin guide and the linear feed drive.

[0014] The jaw guide elements 8 each have a guide groove for a slidingly guided receptacle of a gripping jaw 11 (with return spring 13) and, vertically thereto, a guide bore for the slidingly guided receptacle of a cylindrical pin 12 (each with sliding fits, see Fig. 3). When installed in the frame, the guide grooves of the two jaw guide elements are preferably aligned with one another, the two guide bores are arranged parallel to one another and preferably orthogonal not only to the jaw guides but also to the adaptation surface 4. A guide groove and a guide bore intersect in each jaw guide element; in the intersection area, an end region of the gripping jaw and one end of the cylindrical pin thus meet, forming a wedge-thrust drive. The end region of the gripping jaw and one end of the cylindrical pin are each designed as two bevels that define a common sliding plane 14, wherein the two angles of these bevels to the respective guide directions preferably correspond in sum to the angle between the guide groove and the guide bore, and thus the two bevels lie flat against one another.This creates a coupling of the lateral movements of the gripping jaw and the cylindrical pin with a force deflection, whereby the angle of the sliding plane determines the transmission ratio of the wedge-thrust gear, i.e., between the movement of the cylindrical pin and the movement of the gripping jaw. In the example, the guide directions of the lateral movements of the gripping jaw and the cylindrical pin are arranged at a 90° angle to each other, whereby the orientation of the sliding plane between them is inclined at an angle of 45° to both guide directions (see . Fig. 6a). Preferably, as shown, the sliding plane 14 is defined by the aforementioned slope, or alternatively, the slope is defined only by the gripping jaw.

[0015] The cylindrical pins 12 are in turn pressed from top to bottom against the gripper jaw-side slope by a pneumatic cylinder 10, with the force being transmitted from the cylinder via a distribution yoke 15 to the two cylindrical pins 12 in the example. Preferably, the guide directions of the cylindrical pins are aligned not only parallel to each other, but also to the effective direction of the cylinder (cylinder axis), with all of them more preferably also being at the same distance from the cylinder axis.

[0016] The particularly in Fig. 3 and Fig. When actuated with the piston 24, cylinder 10, shown in detail in Figure 6a, presses axially via the distributor yoke 15 onto the cylindrical pins 12, which then transfer their force to the gripping jaws via the aforementioned force deflection (in the wedge-thrust gear). The counterforce is generated by the gripped insert 2 (see Figure 6a). Fig. 6a) and / or by the return springs 13 of the gripping jaws 11. Force and counterforce ensure that contact between the gripping jaw and the cylindrical pins on the sliding plane is always maintained with a minimum pressure and does not tear. Preferably, the piston is firmly connected to the distributor yoke, and this to the cylindrical pins, e.g., via threaded connections 25.

[0017] In this example, the gripping means preferably comprise two gripping jaws that are guided linearly against one another and that can be moved synchronously in opposite directions via a common pneumatic cylinder and a wedge-type thrust gear. They serve to position, align, and fix the insert in a defined position and axially align it directly at the through-opening in the device. To guide the insert in the gripping means, a vertical guide groove is preferably provided in the gripping surfaces of each of the gripping jaws that directly engage the insert. They ensure that the preferably rotationally symmetrical insert 2 is aligned and fixed in alignment with a heatable pin with a contact tip that is directed towards the insert in the device and can be moved by means of a linear drive.

[0018] Fig. 4a and b as well as 6b show, in a side view, a perspective exploded view, and a side sectional view, the aforementioned heatable pin 16 with contact tip 17 and linear drive 18 for axial pin movement toward the insert 2. The linear drive transmits the linear movement, guided by the axial guide 22 via the guide arm 23, to the heated pin, which is initially moved with the contact tip from a retracted proximal pin position to the insert. This is followed by docking with the insert, whereby the latter is heated via contact. Furthermore, after releasing the gripping means, the insert is taken along and pressed into the plastic component 29 (preferably into a prefabricated target cavity 30) (advanced distal pin position). The force required for pressing in is applied exclusively by the linear drive.

[0019] Fig.Figure 5 shows the pin 16 with heat source 20 in detail. The heat source comprises a metal block 26 arranged around the pin and pressed flat against the pin, with an inserted heating cartridge 27 and a thermistor 31. When the contact tip 17 moves into the insert, heat is transferred into the insert. The heat loss is detected by a temperature sensor 28 near the contact tip and, along with the temperature signal from the thermistor, is used as a control parameter for the heating cartridge.

[0020] In summary, the solution to the problem involves a combination of various sub-elements: gripper fingers, melting device, and heat source, which, in combination with three process steps: gripping, heating, melting, and pressing, are suitable for applying an insert into a plastic component. The gripping function is realized via a feed device, preferably a pneumatic cylinder. The force flow is split into two force flows via a distributor yoke, one per gripper jaw. A wedge-thrust gear redirects the force flow by 90 degrees for each jaw. The gripper jaws for holding the inserts preferably have a V-groove with an opening angle of 120 degrees to ensure centering of the inserts and to be able to grip inserts of different sizes. Melting is realized via an axial guide with a mounted linear drive (linear motor).The linear motor moves a contact tip, preferably made of copper, which is guided by an axial guide. A reference switch is used to detect the motor's position. The contact tip serves as an additional centering element for the inserts on the pin. Furthermore, this contact tip is connected to a metal block, preferably made of aluminum, to which a heating cartridge and, preferably, a thermistor are attached as a thermal sensor. List of reference symbols: 1 device 2 Use 3 frames 4 Adaptation area 5 Passage opening 6 Suspension plate 7 Cover plate 8 Jaw guide element 9 Base plate 10 pneumatic cylinders 11 gripping jaw 12 cylindrical pin 13 Return spring 14 Sliding plane 15 Distribution yoke 16 heated pen 17 Contact tip 18 Linear drive 19 Front plate 20 Heat source 21 temperature sensors 22 Axial guide 23 Guide arm 24 pistons 25 threaded connections 26 metal block 27 Heating cartridge 28 temperature sensors 29 Component 30 Target cavity 31 Thermistor

Claims

[1] Device (1) with insert (2) as a separate component for an automated melting of the insert into a plastic component (29), comprising a) an adaptation surface (4) for supporting the plastic component with a passage opening (5) for the insert, b) a gripping means (11) for positioning, aligning and fixing the insert in a fixed position and in an axial alignment directly at the passage opening in the device, c) a pin (16) with a contact tip (17) directed towards the specified position, d) a heat source (20) interacting with the pin, e) a temperature sensor (21) at the contact tip and f) an axial guide (22) with a linear feed drive (18) for the pin along the axial alignment, on which the pin is movable between a retracted proximal pin position and an advanced distal pin position. [2] Device (1) according to claim 1, characterized by that the insert (2) has a contact surface for the contact tip (17) on the side facing the pin (16), wherein the contact surface and the contact tip simultaneously form a guide for the insert on the pin in the axial alignment. [3] Device (1) according to claim 2, characterized by that the guide has positive torsion transmission elements and in addition to the linear feed drive, a torsion drive is provided for the axial alignment. [4] Device (1) according to one of the preceding claims, characterized by that the adaptation surface (15) comprises a flat support surface or support elements that span a flat surface. [5] Device (1) according to one of the preceding claims, characterized by that the gripping means (11) comprises two gripping jaws which are guided linearly against one another and which can be moved synchronously in opposite directions via a common pneumatic cylinder (10) and a respective wedge-thrust gear. [6] Device (1) according to claim 5, characterized by that at least one of the gripping jaws has groove-shaped alignment means for the insert. [7] Device (1) according to one of the preceding claims, characterized by that the heat source (20) and the pin (16) are permanently connected via a solid-state contact. [8] Device (1) according to one of the preceding claims, characterized by that the linear feed drive (18) comprises a motorized linear drive oriented in the axial alignment. [9] Method (1) for the automated melting of an insert (2) into a plastic component (29), comprising the following method steps: a) providing a device and an insert according to any one of the preceding claims, b) gripping and positioning the insert with the gripping means (11) in a fixed position and axial alignment directly at the passage opening (5) in the device, c) placing the device over the plastic component (29), d) aligning the insert with the device over a target cavity (30) on the plastic component, e) heating the pin (16) by means of the heat source (20) until a target temperature at the contact tip (17) above the melting temperature of the plastic component is reached, wherein the contact tip of the pin assumes a retracted proximal pin position, f) moving the contact tip into axial alignment with the insert using the linear feed drive (18), whereby the insert is guided on the contact tip, g) heating the insert and releasing the gripping means from the insert, h) Moving the pin and the insert by means of the linear feed drive towards the distal pin position, whereby the insert is pressed into the target cavity in the plastic component and melted, i) Extending the contact tip from the insert and cooling the insert and j) Removal of the device without inserting it into the plastic component.

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