Assembly with an electric component heater

Abstract

An assembly consisting of a cylindrical component (4) and an electrical component heater (1) mounted on the cylindrical component (4), wherein the component heater (1) comprises an electrical heating element (2) and a tubular clamping sleeve (3) made of a spring-elastic material for the heating element (2), and the clamping sleeve has a cylindrical outer and inner circumferential surface (35, 30), and wherein the cylindrical component (4) and the clamping sleeve (3) have complementary connecting means comprising a radially projecting projection (40) and a receiving groove (300) corresponding thereto, which engage in a form-fitting manner when the component heater (1) is mounted on the cylindrical component (4), characterized in that the clamping sleeve (3) has the receiving groove (300) in the region of the inner circumferential surface, and the cylindrical component (4) is formed with a radially outwardly projecting projection (40) corresponding thereto.

Description

[0001] The invention relates to an assembly consisting of a cylindrical component and an electrical component heater applied to the cylindrical component, wherein the component heater comprises an electrical heating element and a tubular clamping sleeve made of a spring-elastic material for the heating element and the clamping sleeve has a cylindrical outer and inner surface and wherein the cylindrical component and the clamping sleeve have complementary connecting means comprising a radially projecting projection and a receiving groove corresponding thereto, which engage in a form-fitting manner when the component heater is applied to the cylindrical component.

[0002] Cylindrical components with an applied electric component heater of the type mentioned above are widely known and are used, for example, as nozzle bodies, particularly hot runner nozzles, in the processing of thermoplastics using the injection molding process. The electric component heater, comprising the heating element and the clamping sleeve, is applied to the cylindrical nozzle body to heat it. The heating element consists, for example, of an electrical resistance heating element including a supply line and, if necessary, a sensor in the form of a sheathed thermocouple including the corresponding signal line.The clamping sleeve, sometimes also called a jacket, is an essentially tubular body that fixes the heating element and the sheathed thermocouple, if present, to the cylindrical component, thus ensuring good heat transfer and preventing separation of the component heating from the cylindrical component.

[0003] The installation of such an electric component heater on the cylindrical component should be as easy as possible, without great effort, and, if possible, without the need for special tools. The position of the mounted electric component heater on the cylindrical component should be securely held during operation, for example, during shock loads caused by the operation of an injection molding tool. Furthermore, with regard to good heat transfer, secure contact with the cylindrical component across the entire contact surface is desirable, and disassembly should also be possible using standard tools without damaging the cylindrical component.

[0004] Heating elements are also known from the prior art in which the clamping sleeve consists of a closed tube, e.g., made of brass, into which a resistance heating element is inserted into external grooves. The disadvantage of this design is that the inner diameter of the component heater and the outer diameter of the cylindrical component must have a certain amount of play to enable assembly at all. This creates an air gap, which is detrimental to heat transfer, and also requires additional securing elements, such as clamping screws or circlips, to secure the position.

[0005] DE 20 2018 105 899 U1 discloses a cylindrical component with an electric component heater, in which the clamping sleeve has the shape of a tube with a helical gap running along its entire length and the heating element is accommodated and fixed in a groove. The electric component heater is installed by engaging a suitable turning tool, which allows the component heater to be easily installed and ensures good heat transfer and secure positioning thanks to the clamping force of the clamping sleeve. However, such a turning tool cannot be used in all applications. The relatively high clamping force achieved is also achieved by a correspondingly undersized diameter of the relaxed clamping sleeve, which prevents easy tool-free installation.

[0006] A generic assembly comprising a cylindrical component and a component heater mounted on the cylindrical component, which comprises an electric heating element and a tubular clamping sleeve made of a resilient material for the heating element, is the subject of US Pat. No. 5,558,888. An inner sleeve is provided that can be pushed onto the cylindrical component to be heated and is wrapped on the outside with heating coils. A further sleeve is pushed onto the outer side of the cylindrical component for fixation, which engages positively with the inner sleeve using complementary connecting means. This is very complex.

[0007] The object of the invention is to propose an assembly comprising a cylindrical component and an electric component heater of the type mentioned above, which can be easily assembled and ideally without tools, but nevertheless ensures reliable fixing of the component heater on the cylindrical component and good heat transfer.

[0008] To achieve the stated object, the invention proposes the design of an assembly according to the features of patent claim 1.

[0009] Advantageous embodiments and further developments of the invention are the subject of the dependent claims.

[0010] The inventive proposal provides that the clamping sleeve is formed with the receiving groove in the region of the inner circumferential surface, and the cylindrical component is formed with a corresponding radially outwardly projecting projection. Thus, the cylindrical component and the clamping sleeve have complementary connecting means, comprising a projection projecting radially at a suitable position and a corresponding receiving groove, which engage positively when the component heater is applied to the cylindrical component.

[0011] According to the invention, the radial clamping force of the tubular clamping sleeve surrounding the electric heating element, previously used in the prior art to fix the heating element to the cylindrical component, is replaced by a positive connection, which can be realized through suitable structural measures, preferably as a snap connection without the need for special tools. The required clamping force is reduced to such an extent that easy, tool-free assembly is possible, and the positive connection ensures good heat transfer.

[0012] According to one proposal of the invention, the clamping sleeve can be pushed onto the cylindrical component axially in a plug-in direction until it reaches an end position in which the connecting means engage positively. To fix the heating element to the cylindrical component, the clamping sleeve is pushed axially onto the cylindrical component in the plug-in direction and engages positively when the projection engages in the receiving groove. For example, the projection and the corresponding receiving groove on the cylindrical component and the clamping sleeve can be arranged behind the heating element in the plug-in direction.

[0013] The individual connecting means, i.e. projection and receiving groove, can be provided circumferentially or only in segments on the circumference of the cylindrical component and / or the clamping sleeve.

[0014] Within the scope of the invention, the heating element can be provided both in the area of ​​the outer and in the area of ​​the inner circumferential surface, wherein the outer and inner circumferential surfaces facing the heating element can be either smooth or formed with grooves that at least partially accommodate the heating element.

[0015] According to a further proposal of the invention, the end of the clamping sleeve pointing in the insertion direction can be formed adjacent to the receiving groove, at least in some regions, with a radially elastically expandable tongue on which one of the connecting means is arranged. For example, a receiving groove can be formed on the tongue so that the tongue can be releasably locked to the projection in the manner of a snap hook. Such a tongue can be arranged separately on the clamping sleeve or formed integrally therein, for example, if the end of the clamping sleeve pointing in the insertion direction is shaped accordingly.

[0016] An at least regional design of the tongue is understood to mean a tongue that is formed in segments only over a partial area of ​​the inner circumference of the clamping sleeve up to a continuously circumferential tongue.

[0017] The projection required for the positive locking can be created integrally on the cylindrical surface of the cylindrical component, for example, when manufactured as a turned part, or it can be formed by a radially protruding ring inserted into a correspondingly provided groove. Similarly, a receiving groove can also be created in the surface of the cylindrical component by turning or milling.

[0018] In order to achieve the desired spring elasticity of the clamping sleeve in the radial direction and to enable easy sliding and positive connection of the tubular clamping sleeve onto the cylindrical component, according to a further proposal of the invention, at least one slot can be formed in the clamping sleeve. This at least one slot can, for example, run helically over the longitudinal extent of the clamping sleeve, but different slot extensions, for example axial or, in the developed view of the clamping sleeve, step-like extensions of the at least one slot over its longitudinal extent are also possible within the scope of the invention. Furthermore, such a slot can run either over the entire longitudinal extent of the clamping sleeve or over only a partial area thereof.

[0019] The clamping sleeve is preferably made of a spring-elastic material whose required spring force is maintained between room temperature and approximately 500 °C, so that when the cylindrical component is heated to the desired temperature by the electric heating element in a temperature range which is aimed for, for example, in the nozzle bodies of an injection mold, no significant losses of the clamping force and / or a loss of the form fit have to be accepted.

[0020] The heating element is designed, for example, as an electrical resistance heating element and, according to one proposal of the invention, can be arranged in a meandering or helical manner around the cylindrical component. Both designs are conceivable in which the heating element is pushed directly onto the surface of the cylindrical component and then secured with the clamping sleeve, and designs in which the heating element is inserted and secured in corresponding internal grooves of the clamping sleeve and, together with the latter, is pushed onto the cylindrical component to be heated. The heating element can also be arranged accordingly on the outer surface of the clamping sleeve, in particular in corresponding grooves provided on the outside.

[0021] The cylindrical component itself can, for example, be designed as a hot runner nozzle of an injection molding tool for raw material processing or also of other cylindrical components which serve in particular to convey a plasticized plastic melt.

[0022] Further embodiments and details of the invention are explained in more detail below with reference to the drawings illustrating an exemplary embodiment. They show: Fig. 1 shows a perspective view of a cylindrical component according to an embodiment of the invention; Fig. 2 shows an enlarged view of the radially projecting projection on the cylindrical component according to Fig. 1; Fig. 3 shows a perspective view of a tubular clamping sleeve with an inserted electric heating element according to an embodiment of the invention; Fig. 4 in an enlarged view the design of the receiving groove in the tubular clamping sleeve according to Fig. 3; Fig. 5 shows a perspective view of a cylindrical component according to a further embodiment; Fig. 6 shows an enlarged view of the radially circumferential receiving groove on the cylindrical component according to Fig. 5; Fig. 7 shows a perspective view of a tubular clamping sleeve according to a further embodiment; Fig. 8 in an enlarged view of section AA according to Fig. 7; Fig. 9 is a plan view of another embodiment of a clamping sleeve according to the invention; Fig. 10 a plan view of another embodiment of a clamping sleeve according to the invention.

[0023] From the Fig. 1 shows a perspective view of a cylindrical component 4 in the form of a hot runner nozzle of an injection molding tool for plastics processing. This component 4 has at one axial end a shoulder 41 which is larger than the remaining diameter and with which this component 4 is inserted into an injection molding tool (not shown). At the opposite, conically tapered end, the outlet opening 42 for the melt of the plastic material passed through the component 4 can be seen. In order for the melt to remain in the state of a plastic melt while passing through the component 4, the cylindrical component 4 is heated in its cylindrical section 400, together with the melt channel running through it and ending in the outlet opening 42, by a heating element 2 in the form of an electrical resistance heater which is applied to the outside of the cylindrical component 4 and which is described in more detail in FIG. Fig. 3 is evident.

[0024] The electric heating element 2 is as shown in the Fig. 3 in the region of the inner surface 30 of a tubular clamping sleeve 3 made of a spring-elastic material, the spring force of which is required to achieve a holding force is maintained between room temperature and approximately 500 °C. For this purpose, the electrical heating element 2 can either be fixed in some areas to the inner surface 30 of the clamping sleeve 3, for example, welded or soldered, or it can be inserted into corresponding grooves made in the region of the inner surface 30 of the clamping sleeve 3.

[0025] The clamping sleeve 3 further has a slot 31 extending continuously through the outer surface from the inner surface 30 to the outer surface 35 and extending helically around the clamping sleeve 3 in the axial direction. The heating element 2 extends helically along the inner surface 30 of the clamping sleeve 3.

[0026] In order to ensure the heating of the cylindrical component 4 with this heating element 2 arranged on the inner surface 30 of the clamping sleeve 3, the heating element 2 should come into surface contact with the cylindrical component 4. For this purpose, the Fig. 3, consisting of heating element 2 and clamping sleeve 3, is pushed axially onto the cylindrical component 4 in the region of the cylindrical section 400 in a plug-in direction indicated by arrow S. It is understood that the outer diameter of the cylindrical section 400 of the component 4 and the inner diameter of the heating element 2 as well as the tubular clamping sleeve 3 surrounding or enclosing it are coordinated with one another in such a way that contact is made between the mutually facing surfaces of the cylindrical section 400 and the heating element 2 by exerting a slight radially inwardly directed clamping force of the clamping sleeve 3. The clamping force of the clamping sleeve 3 is brought about by the fact that it is slightly radially expanded in the plug-in direction S when pushed onto the cylindrical component 4, which is made possible by the course of the slot 31.

[0027] In order to determine the desired final position of the heating element 2 and the tubular clamping sleeve 3 on the cylindrical component and to fix the heating element 2 and the clamping sleeve 3 on the cylindrical component 4 in such a way that this positioning is not lost even in the event of strong vibrations and accelerations, such as those that occur during operation of an injection molding tool, the cylindrical component 4 is formed adjacent to the shoulder 41 with a projection 40 projecting radially beyond the cylindrical section 400, which projection is either formed integrally or is formed by a radially projecting ring inserted into a corresponding groove.

[0028] Correspondingly, the tubular clamping sleeve 3 has a circumferential receiving groove 300 at its end pointing in the plug-in direction S, which receiving groove ends in the slot 31. The axial length section of the clamping sleeve 3 that remains from the receiving groove 300 in the plug-in direction S is profiled immediately adjacent to the receiving groove 300 in such a way that it forms a snap hook 301 that widens conically towards the axial end of the clamping sleeve 3 lying in the plug-in direction S. In the exemplary embodiment shown, this snap hook 301 is also formed circumferentially in the region of the inner surface 30 of the tubular clamping sleeve 3 and ends in the slot 31, but in a modification it could also be formed only in segments or regions over the inner circumference of the tubular clamping sleeve 3.

[0029] When the tubular clamping sleeve 3 with the heating element 2 located therein is pushed in the plug-in direction S onto the cylindrical component in the region of the cylindrical section 400 starting from the end 42, the snap hook 301 slides over the radially projecting projection 40 shortly before reaching the desired end position on the cylindrical component 4 and engages with it in a releasable, positive-locking connection, so that the heating element 2 and the clamping sleeve 3 are releasably but reliably fastened in a defined end position on the cylindrical component 4 by simply axially sliding them in the plug-in direction S. The depth of the receiving groove 301 can have a certain excess over the height of the radially projecting projection 40, so that there is corresponding play, which ensures a reliable, positive-locking snap connection of the contact surfaces and thus good heat transfer.

[0030] It is understood that the tubular clamping sleeve 3 together with the heating element 2 can also be easily removed from the cylindrical component 4 by applying corresponding tensile forces directed counter to the insertion direction S, for which purpose only the holding forces achieved by the positive connection between the bead 40 and the receiving groove 300 must be overcome. For example, the clamping sleeve 3 can be designed with bores (not shown) for the engagement of a puller in order to pull it off the cylindrical component 4 counter to the insertion direction S. In order to facilitate this removal as well as the sliding of the clamping sleeve 3 over the projection 40, the projection 40 can, as shown in Fig. 2, it must be conical on its side surfaces lying in and opposite to the plug-in direction S.

[0031] The Fig. 5 to 8 show a different embodiment compared to the embodiment according to Fig. 1 to 4, in which the arrangement of the receiving groove 300 and the projection 40 has been reversed. The same parts have the same reference numerals as in the embodiment according to Fig. 1 to 4 and will not be explained again separately below to avoid repetition unless this is necessary for understanding the invention.

[0032] In contrast to the embodiment according to Fig. 1, the cylindrical component 4 has a cylindrical shape according to the Fig. 5 and Fig. 6, adjacent to the shoulder 41, there is an annular circumferential receiving groove 300 which has been introduced into the surface 400, for example by turning.

[0033] Corresponding to this is the Fig. 7 and Fig. 8, the cylindrical clamping sleeve 3 is provided with a smooth inner surface 30, which has a projection 40 projecting radially inward beyond the cylindrical inner surface 30 only at two diametrically opposite points. The projections 40 engage positively in the receiving groove 300 of the cylindrical component 4 when the clamping sleeve 3 is pushed onto the cylindrical component 4 in the insertion direction S upon reaching the end position. In this respect, the arrangement of the positive connection elements on the cylindrical component 4 and the clamping sleeve 3 in the embodiment according to the Fig. 5 to 8 exactly the opposite to that in the embodiment according to Fig. 1 to 4.

[0034] The radially inwardly projecting projection 40 of the clamping sleeve 3 according to Fig. 7 and Fig. 8 can be produced, for example, by a punctiform plastic deformation acting on the cylindrical outer surface 35, so that a corresponding depression 40a is visible on the outer surface 35.

[0035] Further possible designs of a clamping sleeve 3 are shown in the Fig. 9 and Fig. 10. Here, at the end of the clamping sleeve 3 lying in the plug-in direction S in the embodiment according to Fig. 9 by two slots 37 introduced parallel from the end, not extending over the entire longitudinal extent of the clamping sleeve 3, a radially elastically expandable tongue 36 is formed, on which one of the complementary connecting means is formed, for example in the embodiment according to Fig. 9 a receiving groove 300 formed on the inner surface 30 (not visible here) for cooperating with a projection 40 projecting radially on the cylindrical component 4 as shown in Fig. 1.

[0036] Alternatively, such a tongue 36 may be provided as shown in the Fig. 10 can also be formed by an approximately U-shaped slot 37 at the end of the clamping sleeve 3 pointing in the plug-in direction S, whereby in contrast to the embodiment according to Fig. 9, the slot 37 is not open at the axial end of the clamping sleeve, but is closed at the axial end. Such a slot for forming the tongue 36 can be arranged anywhere along the longitudinal axis of the clamping sleeve 3, for example, in the central longitudinal extension area or at the end thereof facing away from the insertion direction S. In the illustration according to Fig. 10, the tongue 36 carries, by way of example, a radially inwardly projecting projection 40 as shown in Fig. 8, so that a corresponding recess 40a is visible on the outer surface 35. Accordingly, such a design of the clamping sleeve 3 is suitable for interaction with the design of the cylindrical component according to Fig. 5 and Fig. 6 suitable.

[0037] It is understood that the design of the respective connecting means on the tongue 36 is merely exemplary and depends on the configuration of the cylindrical component 4 and the connecting means formed thereon. A person skilled in the art can select which connecting means are designed and provided to form the positive connection between component 4 and clamping sleeve 3.

[0038] With the above-described embodiments, a cylindrical component can be equipped with an electric component heater without the need for tools, secured against loss by a releasable form fit, and also separated from it again, whereby only the space required for axial sliding on or pulling off must be available, which is easily provided, for example, with hot runner systems in an injection molding tool.

Claims

An assembly consisting of a cylindrical component (4) and an electrical component heater (1) mounted on the cylindrical component (4), wherein the component heater (1) comprises an electrical heating element (2) and a tubular clamping sleeve (3) made of a spring-elastic material for the heating element (2), and the clamping sleeve has a cylindrical outer and inner circumferential surface (35, 30), and wherein the cylindrical component (4) and the clamping sleeve (3) have complementary connecting means comprising a radially projecting projection (40) and a corresponding receiving groove (300), which engage in a form-fitting manner when the component heater (1) is mounted on the cylindrical component (4), characterized in that the clamping sleeve (3) is formed with the receiving groove (300) in the region of the inner circumferential surface, and the cylindrical component (4) is formed with a corresponding radially outwardly projecting projection (40). Assembly according to claim 1, characterized in that the clamping sleeve (3) can be plugged onto the cylindrical component (4) axially in a plug-in direction (S) until an end position is reached in which the connecting means engage one another in a form-fitting manner. Assembly according to one of claims 1 or 2, characterized in that the heating element (2) is arranged in the region of the outer or inner surface of the clamping sleeve. Assembly according to one of claims 1 to 3, characterized in that the end of the clamping sleeve (3) pointing in the plug-in direction (S) is formed adjacent to the receiving groove (300) at least in regions with a radially elastically expandable tongue (36) on which one of the complementary connecting means is formed. Assembly according to one of claims 1 to 4, characterized in that the clamping sleeve (3) has at least one slot (31). Assembly according to claim 5, characterized in that the at least one slot (31) runs helically when viewed in the longitudinal extension of the clamping sleeve (3). Assembly according to one of claims 5 or 6, characterized in that the at least one slot (31) runs at least over a partial area of ​​the clamping sleeve (3) or continuously, viewed in the longitudinal extension of the clamping sleeve (3). Assembly according to one of claims 1 to 7, characterized in that the clamping sleeve (3) is formed from a spring-elastic material whose spring force is maintained between room temperature and 500 °C. Assembly according to one of claims 1 to 8, characterized in that the electrical heating element (2) is arranged in a meandering or helical manner around the cylindrical component (4). Use of an assembly according to one of claims 1 to 9 as a hot runner nozzle of an injection molding tool for plastics processing.

Images