Tensionable electric heating device

Abstract

An electric heating device (100, 200, 300) with an axial opening for receiving an object to be heated, with an electric heating element (110, 210, 310) and with a clamping sleeve (130, 230, 330) for generating an adjustable force acting radially towards an axis (A) of the axial opening, wherein at least the clamping sleeve (130, 230, 330) of the electric heating device (100, 200, 300) has at least a section of a recess (131, 231, 331) whose width (b) is variable by means of at least one clamping slide (140, 240, 340), wherein the clamping slide (140, 240, 340) overlaps the recess (131, 231, 331), characterized in that the clamping slide (140, 240, 340) extends at least sectionally between the clamping sleeve (130, 230, 330) and an outer tube formed by an outer shell (160, 260, 360) which has a through-opening (161, 261, 361) that is narrower than the clamping slide (140, 240, 340),so that the clamping slide (140, 240, 340) is captive on the electric heating device (100, 200, 300), while the clamping slide (140, 240, 340) can be actuated over its entire functional range.

Description

[0001] The invention further develops an electric heating device with the features of the preamble of patent claim 1.

[0002] Heating devices with an electric heating element are known from the prior art. These devices are slid onto a body to be heated and secured there by clamping. For example, such heating devices are used in injection molding machines or in hot runner and manifold systems as nozzle heaters for heating nozzle bodies.

[0003] It is already known from the prior art on the market to provide a one-piece clamping sleeve around the heating element, which is in direct contact with the heating element or, for example, when the latter is embedded between an inner and an outer metal sleeve, in indirect contact with the heating element. The clamping sleeve has, viewed in the radial direction, overlapping sections, between which a wedge mechanism operated by a screw is arranged. If the screw is turned in one direction, the wedge mechanism is moved so that its height changes, which increases the distance between the overlapping sections of the clamping sleeve. This, due to the essentially constant length of the clamping sleeve, leads to the heating device being clamped firmly onto the body to be heated. Turning the screw in the other direction allows the clamping sleeve to be released again.

[0004] The problem with this heating device with a clamping sleeve is the increased space required by the clamping mechanism in the radial direction due to the wedge mechanism, because in many cases, especially with hot runner nozzles, the individual nozzles to be heated are arranged in blocks and between the nozzle and the block there is only a relatively narrow, tubular channel into which the heating device must fit.

[0005] Particularly for applications where such increased space requirements cannot be met, heating devices with clamping devices have been developed, as disclosed, for example, in DE 10 2013 111 303 A1 or DE 20 2011 003 451 U1. These heating devices have a slot running through them in the axial direction. Furthermore, clamping slides are provided that bridge the slot and interact with the outer casing of the heating device in such a way that their axial displacement changes the width of the slot in the circumferential direction, thereby achieving clamping on the body to be heated. In practice, however, it has been shown that these clamping slides can, on the one hand, get lost and, on the other hand, cannot always generate the desired clamping forces.

[0006] DE 10 2009 025 164 A1 suggests arranging a heating device within tubular housing sections of an injection molding device.

[0007] DE 200 15 016 U1 suggests clamping a clampable heating device using a tool.

[0008] The object of the invention is therefore to provide a tensionable heating device in which the tensioning device is less likely to be lost. This object is achieved by a heating device having the features of patent claim 1. Advantageous further developments of the invention are the subject of the dependent claims.

[0009] The electric heating device according to the invention has an axial opening for receiving an object to be heated, the outer contour of which can typically be cylindrical at least in sections, an electric heating element - preferably surrounding the axial opening at least in sections - and a clamping jacket - preferably in the shape of a cylinder jacket or a truncated cone - for generating an adjustable force acting radially in the direction of an axis of the axial opening.

[0010] The following explanations should contribute to an even clearer understanding of this inherently unambiguous terminology: The geometry of such a heating device can preferably be described using concepts from the geometry of the cylinder or the generalized cylinder and cylindrical coordinates. The direction of the cylinder axis is determined by the axis that defines the axial opening of the heating device, into which the object to be heated is usually inserted, and is referred to below as the axial direction.

[0011] A force acts radially in the direction of this axis if it acts on a connecting line perpendicular to this axis between a point on the cylinder jacket and a point on the axis in the direction of the axis and is therefore particularly suitable for pressing the electric heating device against an object to be heated arranged in its axial opening.

[0012] The course of an electric heating element in space can be described in particular in these cylindrical coordinates, i.e. by the position on the axis of the axial opening, the distance in the radial direction from the axis of the axial opening and a polar angle between 0° and 360°. The electric heating element surrounds the axial opening at least in sections if different polar angles for describing the course of the electric heating element lie in the region of the axial opening. This is particularly the case if the side of the electric heating element facing the axial opening lies on an imaginary cylinder or truncated cone surface that encloses the axial opening - preferably coaxially, which in turn is particularly the case if the electric heating element runs in a spiral or meandering manner on an imaginary cylinder or truncated cone surface, whereby the gradient can vary in the direction parallel to the cylinder or truncated cone axis.

[0013] According to the invention, at least the clamping sleeve of the electric heating device is penetrated at least in sections by a recess, which can be designed, in particular, as a slot. A recess is therefore also understood to mean, in particular, an opening or perforation; groups of openings or perforations are also conceivable. The recess penetrates the clamping sleeve at least in sections and therefore does not necessarily have to extend over its entire length.

[0014] The width of the recess or in particular of the slot, which can be understood as the distance from each other between edge points of the recess lying essentially perpendicular to the axis of the axial opening, must be variable by means of at least one clamping slide which overlaps the recess at least in sections.

[0015] An alternative description of the fact that the width of the recess can be varied by means of the clamping slide, which at least partially overlaps the recess, can again be made by referring to a description of the recess in cylindrical coordinates: At each point on the cylinder axis where a recess is present, it covers a specific polar angle range. If the polar angle range covered by the recess varies with different positions of the clamping slide at such points on the cylinder axis, the width of the recess can be varied by means of the clamping slide.

[0016] Preferably, the recess, particularly if it is designed as a slot, extends from one end of the electric heating device; particularly preferably, it runs continuously from one end to the other end, although this does not necessarily have to be in a straight line.

[0017] A key feature of the invention is that the clamping slide is arranged, at least in sections, between the clamping sleeve and an outer tube. This directly ensures that the clamping slide cannot be lost, because the outer tube holds the clamping slide captively in the guide that defines its movement; it can no longer fall out of the guide.

[0018] Typically, this guide is defined by a recess, e.g. an opening, a recess or a groove, in the clamping sleeve or clamping slide, into which a projection engages, which is arranged on the clamping slide or clamping sleeve, wherein the projection is preferably adapted to the width of the recess.

[0019] It should be noted in particular that in various embodiments of electrical heating devices according to the invention, the clamping jacket can be implemented on the one hand as a separate, additional component, for example an additional, separate jacket, but on the other hand also by different components of the electrical heating device itself. For example, in electrical heating devices in which the electrical heating element is embedded in a powder or granulate with good heat conduction, which fills the interior space between a tubular inner jacket with a recess, which can in particular be designed as a slot, and a tubular jacket, usually arranged concentrically thereto, with a recess, which can in particular be designed as a slot, which are connected to one another by lateral boundary surfaces at the edges of the recesses or slots, the clamping jacket can be formed by the tubular jacket with a recess, in particular a slot.

[0020] In embodiments in which a coiled electrical heating element in the form of a tubular coil cartridge is surrounded by a tubular casing with a recess, which can in particular be designed as a slot, against which it rests directly, this casing can also form the clamping casing. And in embodiments in which a tubular coil cartridge is inserted into a groove made in a metal surface, wherein the metal surface is a surface of a metal body preferably in the form of a - in particular slotted - tube, wherein this shape can, for example, be machined from solid but can also be produced by rolling up a metal plate before or after the tubular coil cartridge is inserted, this metal body can form the clamping casing; however, the clamping casing can also be formed by an additional slotted tube pushed onto the slotted tube thus defined.

[0021] In all cases, however, an additional outer tube must be present that covers the clamping slide at least in sections and thus fixes it.

[0022] If the clamping sleeve and / or the outer tube have a recess in which the clamping slide is arranged at least in part - in particular with its lower region facing the axis of the axial opening in the case of a recess in the clamping sleeve or with its upper region facing away from the axis of the axial opening in the case of a recess in the outer tube - such an arrangement can be avoided, which would result in higher installation space requirements than those of known electrical heating devices with clamping slides. This applies in particular if the recess is so deep that the clamping slide can be fully immersed in it and its surface is flush with the surface surrounding the recess.

[0023] A preferred embodiment of the invention is one in which the guides are designed such that the clamping slide has at least one radially inwardly projecting projection on each side of the recess, in particular the slot, and that each projection engages in a depression, in particular a cutout, groove or opening, in the clamping casing that runs obliquely or curved relative to the axis of the axial opening, so that an axial movement of the clamping slide leads to a change in the width of the recess, in particular the slot, because different sections of the recess are then at different distances from the nearest edge of the recess, in particular the slot, while the distance between the inwardly projecting projections remains constant. If this is the case, the clamping slide can be made of thinner material. However, the recesses can also be provided on the clamping slide and the projections on the clamping casing, conversely.

[0024] To establish and release the tension, it is advantageous if the clamping slide has at least one tool holder and / or if the clamping casing has at least one tool holder outside the area in which the clamping slide is displaceable.

[0025] In particular, the tool holder in the clamping sleeve can be formed very easily by a local widening of the gap.

[0026] In particular, pliers whose jaws are modified to fit into such tool holders can be well-suited for adjustment. This need for modification is preferably avoided by designing the tool holders in the clamping slide and / or clamping sleeve to accommodate a pliers jaw.

[0027] It is particularly advantageous if the interaction between the clamping slide and the clamping sleeve is achieved via separate projections that are attached to the clamping slide or the clamping sleeve. "Separate" means that these projections are not integrally formed, but rather are originally additional components that are subsequently attached to the clamping slide or clamping sleeve, e.g., by welding, soldering, or gluing.

[0028] If the outer tube also has a recess, in particular a slot, the geometry of which is adapted to the geometry of the recess, in particular the slot of the clamping sleeve, and the outer tube is fixed to the clamping sleeve, it can be avoided that, depending on the clamping state, the clamping sleeve with its side opposite the recess, in particular the slot, lifts off from the outer tube during clamping.

[0029] The invention is explained in more detail below with reference to figures illustrating exemplary embodiments. It shows: Fig. 1a: an exploded view of a first embodiment of an electric heating device, Fig. 1b: an overall view of the electric heating device from Fig. 1a, Fig. 1c: a view of the clamping device of the electric heater from Fig. 1b in a relaxed state, Fig. 1d: a cross-section through the electric heating device from Fig. 1b in a relaxed state, Fig. 1e: a view of the clamping device of the electric heater from Fig. 1b in tensioned state, Fig. 1f: a cross-section through the electric heating device from Fig. 1b in tensioned state, Fig. 2a: an overall view of a second embodiment of an electric heating device, Fig. 2b: a partially opened enlargement of Fig. 2a, which shows the clamping device, Fig. 2c: a cross-section through the electric heating device from Fig. 2a in the area of ​​the connecting elements between the outer tube and the clamping sleeve, Fig. 2d: an enlarged section from Fig. 2c, Fig. 3a: an exploded view of a first embodiment of an electric heating device, and Fig. 3b: an overall view of the electric heating device from Fig. 3a.

[0030] Fig. 1b shows an overall view of an electric heating device 100 and Fig. 1a is an exploded view of this electric heating device 100. The electric heating device 100 has a substantially hollow cylindrical geometry, the cylinder axis of which forms the axis A of its axial opening, into which the object to be heated can be inserted and on which it can then be held by actuating a clamping device 150 which is arranged in Fig. 1c and 1e, respectively, are shown enlarged in the relaxed and tensioned states, respectively, the electric heating device 100 is fixed. The axial opening is defined by an inner metal casing rolled into a hollow cylinder, which here forms the tensioning casing 130. The casing has a groove into which an electric heating element 110, which can be, for example, a coiled tubing cartridge, is inserted. This arrangement, in itself, already represents a functional electric heating device, thus forming the actual electric heating device in this embodiment.

[0031] The inner metal casing or clamping casing 130 is penetrated lengthwise by a recess 131, designed here as a slot, which runs through a depression in the form of a receptacle 132 for a clamping slide 140. The receptacle 132 has a base as a support surface on which the clamping slide 140 rests. The thickness of the clamping slide 140 and the depth of the receptacle 132 are coordinated such that the clamping slide 140 is flush with the radially outer surface of the inner metal casing or clamping casing 130. The length of the receptacle 132 in the axial direction is greater than the length of the clamping slide 140, so that the clamping slide 140 can be moved in this direction within the receptacle 132.

[0032] The clamping slide 140 has a pair of projections 141 arranged on different sides of the slot forming the recess 131, symmetrically to the slot, which extend radially inwardly toward the axis A. As shown in the Fig. 1a, these projections 141 are preferably formed by separate parts which are fitted into corresponding openings 142 of the clamping slide 140 and fixed there, here welded, so that on the outside they are aligned with the outer surface of the clamping slide 140 and on the inside they protrude inwards beyond the inner surface of the clamping slide facing the axis A.

[0033] In addition, the clamping slide 140 has a tool holder 143 in its central area.

[0034] The variability of the width b of the slot forming the recess 131 is due to the fact that the clamping casing 130 for the clamping slide 140 has a pair of recesses 133 in the base of the receptacle 132 arranged on different sides of the slot symmetrically to the slot, of which in the Fig. 1a to 1f, but only one is visible in each case. The recesses 133 are designed as perforations, thus completely penetrating the clamping sleeve 130. They each extend obliquely relative to the axis A of the axial opening, so that the ends 133b are each closer to the edge of the slot forming the recess 131 than the ends 133a.

[0035] The recesses 133 receive the projections 141 of the clamping slide 140 and, in cooperation with them, form a guide. Because the distance between the respective pairs of projections 141 of the clamping slide 140 remains constant, a change in the gap width b is forced upon movement of the clamping slide in this guide, as the Fig. 1c and Fig. 1e illustrate.

[0036] Furthermore, two tool holders 134, 135 can be seen on the clamping casing 130, which are designed as a local extension of the slot forming the recess 131.

[0037] By comparing the cross-sectional views of the Fig. 1d and Fig. 1f it can be seen that the tensioning of the tensioning device in this embodiment of the invention results in the fact that when the heating device is tensioned, as in the illustration of the tensioned heating device 100 in Fig. 1f is particularly clearly visible, a gap 139 is created between the clamping slide 140 and the clamping jacket 130, which gap is largest on the side of the clamping jacket opposite the slot forming the recess 131.

[0038] The electric heating device 100 furthermore has an outer casing 160 which is pushed onto the actual electric heating device and has a through-opening 161 which allows access to the tool holders 134, 135, 143, but which has a smaller width than the clamping slide 140, i.e. it extends over a smaller polar angle range, so that the clamping slide is arranged in sections between the clamping casing 130, here more precisely the base of the holder 132, and the outer casing 160 and is thus arranged captively on the electric heating device, while the actuation of the clamping slide 140, in particular the introduction of a clamping tool into the tool holder 143 of the clamping slide 140 and the clamping or unclamping of the electric heating device 100 with this tool, is possible over its entire functional range.

[0039] Accordingly, the clamping slide 140 and the clamping sleeve 160 form the clamping device 150. If the clamping slide 140 is displaced in the direction in which the distance between the recesses 133 increases, the gap width b is reduced, thereby clamping the electric heating device 100; a displacement of the clamping slide 140 in the opposite direction leads to an increase in the gap b and a relaxation of the electric heating device 100.

[0040] The Fig. The electric heating device 200 shown in Figures 2a to 2d with electric heating element 210, clamping casing 230 with recess 231 designed here as a slot, receptacle 232, depressions 233 and tool receptacles 234, 235, clamping slide 240 with projections 241, openings 242 and tool receptacle 243 as well as outer casing 260 with through-opening 261, is largely identical to the electric heating device 100 according to the Fig. 1a to 1f, so that reference can be made to their description, wherein the reference numerals are derived from the reference numerals used there by adding 100. The difference between these two embodiments is that the outer casing 260 of the electric heating device 200 also has a recess 262 designed as a continuous slot and is at least selectively attached to the clamping casing, which is particularly well illustrated in the illustration of the Fig. 2c and the corresponding enlarged section of the Fig. 2d. This fastening is achieved by providing bores 238 in the clamping sleeve 230, into which sections 263 of the outer sleeve 260, which would otherwise cover the respective bore 238, are bent. As a consequence of this measure, the clamping of the clamping sleeve also has a direct effect on the outer sleeve, which prevents the formation of a gap such as the gap 139 in the electric heating device 100.

[0041] The Fig. 3a and Fig. 3b, with electric heating element 310, clamping casing 330 with a recess 331 designed here as a slot, receptacle 332, depressions 333 and tool receptacles 334, 335, clamping slide 340 with projections 341, openings 342 and tool receptacle 343 as well as outer casing 360 with through-opening 361, is largely identical to the electric heating device 100 according to the Fig.1a to 1f, so that reference can be made to their descriptions, wherein the reference numerals are derived from the reference numerals used therein by adding 200. The difference between these two embodiments is that the clamping casing 330 has an additional receiving groove 337 for a thermocouple 370, that the shape of the recess 331 formed by the slot deviates from the shape of a continuous straight line, and that the clamping slide 340 is arranged in the lateral region of the electric heating device 300. List of reference symbols 100,200,300 electric heater 110,210,310 electric heating element 130,230,330 clamping sleeve 131,231,331 recess 132,232,332 recording 133,233,333 Deepening 133a,133b,333a,333b End 134,135,234,235,334,335 tool holder 140,240,340 clamping slide 141,241,341 lead 142,242,342 Opening 143,243,343 tool holder 139 gap 150,250,350 clamping device 160,260,260 outer jacket 161,261,361 Access opening 262 recess Section 263 337 mounting groove 370 thermocouple A axis b width

Claims

[1] Electric heating device (100, 200, 300) with an axial opening for receiving an object to be heated, with an electric heating element (110, 210, 310) and with a clamping sleeve (130, 230, 330) for generating an adjustable force acting radially in the direction of an axis (A) of the axial opening, wherein at least the clamping sleeve (130, 230, 330) of the electric heating device (100, 200, 300) has, at least in sections, a recess (131, 231, 331), the width (b) of which can be changed by means of at least one clamping slide (140, 240, 340), wherein the clamping slide (140, 240, 340) engages over the recess (131, 231, 331), characterized bythat the clamping slide (140,240,34) is arranged at least in sections between the clamping casing (130,230,330) and an outer tube which is formed by an outer casing (160,260,360) which has a through-opening (161,261,361) which has a smaller width than the clamping slide (140,240,340), so that the clamping slide (140,240,340) is arranged captively on the electrical heating device (100,200,300), while the actuation of the clamping slide (140,240,340) is possible over its entire functional range. [2] Electric heating device (100,200,300) according to claim 1, characterized by that the clamping casing (130,230,330) and / or the outer tube (160,260,360) have a recess in which the clamping slide (130,230,330) is arranged at least in sections. [3] Electric heating device (100,200,300) according to claim 1 or 2, characterized bythat the clamping slide (140,240,340) has at least one radially inwardly projecting projection (141,241,341) on each side of the recess (131,231,331) and that each projection (141,241,341) engages in a recess (133,233,333) in the clamping casing (130,230,330) which runs obliquely or curved relative to the axis (A) of the axial opening, so that an axial movement of the clamping slide (140,240,340) leads to a change in the width (b) of the recess (131,231,331). [4] Electric heating device (100,200,300) according to one of claims 1 to 3, characterized by that the clamping slide (140,240,340) has at least one tool holder (143,243,343). [5] Electric heating device (100, 200, 300) according to one of claims 1 to 4, characterized by that the clamping casing (130,230,330) has at least one tool holder (134,135,234,235,334,335) outside the area in which the clamping slide (140,240,340) is displaceable. [6] Electric heating device (100,200,300) according to claim 5, characterized by that the tool holder (134,135,234,235,334,335) in the clamping casing (130,230,330) is formed by a local widening of the gap (131,231,331). [7] Electric heating device (100,200,300) according to one of claims 4 to 6, characterized by that the tool holder (134,135,143,234,235,243,334,335,343) is designed to receive the jaws of a pair of pliers. [8] Electric heating device (100,200,300) according to one of claims 1 to 7, characterized by that the interaction between the clamping slide (140,240,340) and the clamping jacket (130,230,330) is established via separate projections (141,241,341) which are fastened to the clamping slide (140,240,340) or to the clamping jacket (130,230,330). [9] Electric heating device (100,200,300) according to one of claims 1 to 8, characterized bythat the outer tube (160,260,360) also has a recess (261) whose geometry is adapted to the geometry of the recess (131,231,331) of the clamping jacket (130,230,330) and that the outer tube (160,260,360) is fixed to the clamping jacket (130,230,330).

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