FIELD

The present disclosure relates to heater bands, more specifically, heater bands used in plastic processing machinery.

BACKGROUND

The background information herein below relates to the present disclosure but is not necessarily prior art.

Ceramic band heaters are used on barrels of plastics processing machines to allow the flow of melted polymeric compounds at a predetermined pressure, into mould cavities through barrels. In order to ensure optimal flow characteristics of the melted polymer, the barrels are provided with ceramic band heaters. A conventional band heater comprises a plurality of ceramic blocks interlocked with each other. A plurality of heating element is disposed in the ceramic blocks in such a manner that each heating element is vertically mounted inside a cavity provided in each ceramic block. The heating element is electrically activated to ensure a controlled temperature environment inside the barrel.

However, the mode of transfer of heat from the heating elements of the conventional heating band to the barrel is conduction, which limits the rate of heat transfer. To compensate for the high temperature required in the barrel, more heating elements are required which in turn makes the band heater bulky and adds to the consumption of electricity. Moreover, the conventional band heater has limited provisions to lower the excess heat developed in the barrel. More specifically, cooling elements are provided in the band heater distinctively away from the heating elements. As a result, the maximum Watt density that could be achieved is limited. Additionally, since the heating elements are vertically mounted along the band heater, failure of any heating element would cause failure in transmission of heat at a particular location in the band heater where the heating element is located, thereby causing non-uniform heat distribution across the band heater. Non-uniform distribution of heat causes warping of the heating elements, and thus results in failure of the band heater. To satisfy all the requirements necessary to provide heat for optimal flow of the polymer, the barrel is compactly configured, thereby hampering the productivity. There, is therefore, felt a need for a band heater assembly that alleviates the aforementioned drawbacks.

OBJECTS

Some of the objects of the present disclosure are described herein below: An object of the present disclosure is to provide a band heater assembly for plastic processing machinery.

Another object of the present disclosure is to provide a band heater assembly that ensures optimal flow characteristics of melted polymer through a barrel.

Still another object of the present disclosure is to provide a band heater assembly that is thermally efficient.

Another object of the present disclosure is to provide a band heater assembly that has a simple design.

Yet another object of the present disclosure is to provide a band heater assembly that is simple to manufacture. Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

SUMMARY

The present disclosure envisages a band heater for plastic processing machinery. The band heater assembly comprises a barrel configured to be connected to the plastic processing machinery, a thermally insulating band defined by a plurality of channel blocks made of a thermally insulating material and interlocked with each other by means of a securing means at least one channel defined on the operative interior surface of each of the channel blocks, heating elements held by the band by being embedded in the channels to produce heat and to control the temperature inside the barrel. In an embodiment, each channel block is defined by an operative interior surface, that rests against the outer surface of the barrel, and an operative exterior surface.

In another embodiment, channel block includes lateral surfaces whose operative top ends are configured to rest against the surface of the barrel, a rib provided at the central portion of the channel block, a segmented web defined on the opposite side of the rib, and lateral projections on the operative inner side of the lateral surfaces at the same height as that of the head of the rib. The heating elements are secured firmly between the lateral surfaces under the ribs and the lateral projections by sliding therein.

In another embodiment, the band heater assembly is communicatively coupled with a remote device (not specifically shown in figures) that is configured to control the temperature of the heater assembly.

In a preferred embodiment, the lateral surfaces of the channel block have curved edges, wherein the operative front edge of each lateral surface is convex, and the operative rear edge is concave with a curvature that is complementary to that of the operative front edge. The channel blocks are placed in the band such that the operative front edge of the lateral surface of one channel block abuts the operative rear edge of the lateral surface of an adjacent channel block, thereby providing a partial overlapping configuration between adjacent channel blocks.

In an embodiment, the channel blocks are formed of vacuum cast ceramic fibre material.

In an embodiment, the band is housed underneath a stainless steel sheet provided with serrated edges folded over to secure the ends.

In an embodiment, the segmented webs are configured to facilitate radial rib of the attachment of cooling elements which, in an operative configuration, have a radial rib with respect to curvature of the barrel, for providing heat sinks for faster cooling when required.

In an embodiment, the channel blocks are screwed to the channel blocks and the barrel.

Preferably, the heating elements are made of sheets of a nichrome alloy.

In an embodiment, each heating element is disposed in the band with an equidistant gap maintained in between each heating element for uniform distribution of the heat.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWING

A band heater assembly, of the present disclosure, for plastic processing machinery will now be described with the help of the accompanying drawing, in which: Figure 1A illustrates an isometric view of the band heater assembly, in accordance with an embodiment of the present disclosure;

Figure IB illustrates a front view of the assembly of Figure 1A;

Figure 1C illustrates a side view of the assembly of Figure 1A; Figure 2A illustrates an isometric view of a buffer element of the assembly of Figure 1;

Figure 2B illustrates front view of the buffer element of the assembly of Figure 2A; and

Figure 3A and Figure 3B illustrate different views of a first exemplary embodiment of the buffer element of Figure 2A with heating elements disposed therein;

Figure 4A and Figure 4B illustrate different views of a second exemplary embodiment of the buffer element of Figure 2A with heating elements disposed therein;

Figure 5A and Figure 5B illustrate different views of a third exemplary embodiment of the buffer element of Figure 2A with heating elements disposed therein.

LIST OF REFERENCE NUMERALS

100 - Band heater assembly 105 - Band

105a, 105b, 105c, ..., 105n - Channel blocks 110 - Barrel 115 - Heating element 120 - Interlocking pin 125 - Rib

130 - Lateral surface

135 - Segmented web

DESCRIPTION Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.

Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail. The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.

When an element is referred to as being "mounted on," “engaged to,” "connected to," or "coupled to" another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements. The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure. Terms such as “inner,” “outer,” "beneath," "below," "lower," "above," "upper," and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.

Typically, a band heater assembly is employed to wrap around a screw barrel of a melted resin machine to provide insulation and effectively control the temperature of the molten plastic flowing through the barrel such that the quality of the resin is uniformly maintained. In an embodiment, the melted resin machine may be any machine configured to prepare resin for moulding. The machine may be a plastic injection moulding machine or extrusion machine.

A preferred embodiment of a band heater assembly, of the present disclosure, for a molten- resin-conveying barrel used in plastic processing machinery will now be described in detail with reference to Figure 1 through Figure 5B. The preferred embodiment does not limit the scope and ambit of the disclosure.

The band heater assembly 100 (hereinafter referred to as “the assembly 100”) includes a thermally insulating band 105 that wraps around a screw barrel 110. The assembly 100 is communicatively coupled with a remote device (not specifically shown in figures) that is configured to control the temperature of the assembly 100. The band 105 is defined by a plurality of channel blocks 105a, 105b, 105c, ..., 105n interlocked with each other by means of a securing means, such as an interlocking pin 120. Each channel block 105a, 105b, 105c, ..., 105n is defined by an operative interior surface, that faces the outer surface of the barrel 110, and an operative exterior surface. The channel block 105a, 105b, 105c, ..., 105n is further provided with a channel configured on the operative interior surface. The channel blocks 105a, 105b, 105c, ..., 105n are of an insulating material. In a preferred embodiment, the channel blocks 105a, 105b, 105c, ..., 105n are of vacuum cast ceramic fibre material. The band 105 is housed underneath a stainless steel sheet provided with serrated edges folded over to secure the ends.

The assembly 100 further includes heating elements 115 and embedded in the band 105 to produce the desired levels of heat and control the temperature inside the barrel 110. Embedding the heating elements 115 in the channel of the channel blocks 105a, 105b, 105c, ..., 105n protects the heating elements 115 from damage and corrosion. Each heating element 115 is disposed in the band 105 such that an equidistant gap is maintained in between each heating element 115, thereby resulting in uniform distribution of the heat. As a result, a lower number of heating elements 115 is required for achieving the desired heat distribution. Further, failure of any heating element 115 would not affect the heat distribution longitudinally across the band 105. Moreover, since each heating element 115 is wound across the band 105, more surface area for transmission of heat is acquired.

According to an aspect of the present disclosure, the heating elements 115 are held by the channel blocks 105a, 105b, 105c, ..., 105n at a predetermined distance from the surface of the barrel 110, and hence configured to efficiently transmit heat via radiation. The gap between the heating elements 115 and the surface of the barrel 110 can also be configured to allow the passage of air/cooling liquid for cooling purpose.

The lateral surfaces 130 of each of the channel blocks 105a, 105b, 105c, ... ,105n have curved edges. The operative front edge of each lateral surface 130 is convex, and the operative rear edge is concave with a curvature that is complementary to that of the operative front edge. The channel blocks 105a, 105b, 105c, ..., 105n are placed in the band 105 such that the operative front edge of the lateral surface of one channel block abuts the operative rear edge of the lateral surface of an adjacent channel block, thereby providing a partial overlapping configuration between adjacent channel blocks, or in other words, a complete sealing between along the band 105. The resultant absence of any gap between the channel blocks of the band 105 helps minimize any loss of heat.

The channel block 105a, 105b, 105c, ..., 105n is a strip defined by a desired number of ribs 125 configured on the operatively inner surface of the strip. Each rib 125 is configured with a T-shaped head. The operative top ends of the lateral surfaces 130 of the channel block 105a, 105b, 105c, ..., 105n are configured to rest against the surface of the barrel 110. Operative inner side of the lateral surfaces 130 have lateral projections at the same height as that of the head of the rib 125. The heating elements 115 are secured firmly between the lateral surfaces under the ribs 125 and the lateral projections by sliding therein.

Further, segmented webs 135 are configured on the operatively outer surface of the strip. The segmented webs 135 are configured to facilitate attachment of cooling elements which, in an operative configuration, have a radial rib with respect to curvature of the barrel 110, thereby providing higher rate of heat dissipation for faster cooling when required.

The arrangement of the heating elements 115 and the cooling elements across the band 105 ensures temperature ranges in the barrel which can be controlled as per application, thereby maintain optimal flow characteristics of the polymer through the barrel. Further, heat is uniformly distributed across the band 105. As a result, warping of the heating elements is avoided. Additionally, the arrangement of the heating elements ensures simplicity in the design of the assembly 100.

In one embodiment, the segmented webs 135 are formed by extrusion process and assembled with the channel block.

In an embodiment, the assembly 100 is covered with an insulating sheet (not specifically shown in figures) to avoid the heat from the assembly 100 from escaping into the atmosphere.

The assembly 100 of the present disclosure is simple in configuration and manufacturing.

In an embodiment, the assembly 100 is configured to wrap around a barrel 110 having diametrical dimension of 75mm or more. In another embodiment, the assembly 100 is configured to encase a barrel 110 having different geometrical dimensions. In another embodiment, the width and length of the assembly 100 can be expanded according to the application.

In an embodiment, the heating elements 115 are configured to radiate heat up to 100 watt/cm .

Preferably, the heating element 115 is a resistance coil. In an embodiment, the resistance coil is of nichrome alloy. In another embodiment, the resistance coil is of aluminium.

Figure 3 A through Figure 5B illustrate different exemplary embodiments of the band 105 of the present disclosure. More specifically, Figures 3A and 3B illustrate a first exemplary embodiment showing a band 105 having a configuration of 2 x 40mm, wherein a first channel block 105a having a length of 40mm is interlocked with a channel block 105b having a length of 40mm. The heating elements 115 are disposed on the channel blocks 105a, 105b and locked in between the ribs 125 and the lateral surfaces 130 of the channel blocks 105a, 105b. Figures 4A and 4B illustrate a second exemplary embodiment, wherein a first channel block 105a having a length of 40mm is interlocked with a second channel block 105b having a length of 75mm. The heating elements 115 are disposed on the channel block 105a, 105b and locked in between the ribs 125 and the lateral surfaces 130 of the channel blocks 105a, 105b. Figures 5A and 5B illustrate a third exemplary embodiment wherein a first channel block 105a having a length of 75mm is interlocked with a second channel block 105b having a length of 75mm. The heating elements 115 are disposed on the channel blocks 105a, 105b and locked in between the ribs 125 and the lateral surfaces 130 of the channel blocks 105a, 105b.

The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.

TECHNICAL ADVANCEMENT AND ECONOMICAL SIGNIFICANCE

The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a band heater assembly for plastic processing machinery, that:

• is efficient;

• provides controlled heat required for optimal flow of the melted polymer;

• transfers heat upto 100 watt/cm through radiation;

• prevents warping of heating elements;

• has simple design; and

• is easy to manufacture.

The foregoing description of the specific embodiments so fully reveals the general nature of the embodiments herein that others may, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein may be practiced with modification within the spirit and scope of the embodiments as described herein. Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

Any discussion of documents, acts, materials, apparatus, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments may be made and that many changes may be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.