JP3681593B2 - Resin sheet heating apparatus and resin sheet heating method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a resin sheet heating apparatus and a resin sheet heating method using the same.
[0002]
[Prior art]
  Conventionally, there have been the following technologies in such fields.
[0003]
  FIG. 19 is a view showing an outline of such a continuous sheet thermoforming machine.
[0004]
  In this figure, 101 is a roll-shaped resin sheet held by the sheet support portion, and 102 is a sheet heating zone provided on the downstream side of the sheet support portion for heating the resin sheet 101 from above and below. Reference numeral 103 denotes a sheet molding zone provided on the downstream side of the sheet heating zone 102. A mold (upper and lower molds) 104 is disposed so as to sandwich the resin sheet 101 from the vertical direction. Reference numeral 105 denotes a table disposed between the upper and lower molds 104, and 107 denotes a sheet supply unit.
[0005]
  Conventionally, a heater mainly used for heating a resin sheet has a maximum temperature of about 300 ° C. to 500 ° C. in which a filament heating element is embedded in ceramic, and a wavelength of radiant energy of about 4.0 μm to 7.0 μm. Infrared heater.
[0006]
  As shown in FIG. 19, this is installed above and below the heating zone 102 of the continuous sheet thermoforming machine, and the sheet 101 is heated by indirect heating from above and below the sheet 101. When the resin sheet 101 heated in the heating zone 102 reaches a certain molding temperature or a certain heating time, it is sent to the sheet molding zone 103 located adjacent to the heating zone 102 and molded.
[0007]
  Here, when the resin sheet 101 is a foamed resin sheet, the conventional far-infrared heater takes two or three heating zones 102, heats the sheet for two shots or three shots, and then enters the next molding zone 103. It is necessary to send and form the sheet. It had to be heated for a long time because of its low heating capacity.
[0008]
  Accordingly, the heating time is required to be twice or three times as long as the molding time (molding cycle), and a long time is required for heating. On the other hand, if the heating zone 102 is lengthened and the molding cycle is shortened, the apparatus becomes long. Conversely, if the apparatus is shortened, the heating time becomes long.
[0009]
  In general, in the case of a transparent non-foamed sheet such as a crystalline polypropylene sheet (PP sheet), a polyethylene terephthalate sheet (PET sheet) or a polybutylene terephthalate sheet (PBT sheet), it is thin even by heating with a conventional far-infrared heater. In the case of a material (about 0.2 to 0.5 mm), in the sheet heating zone 102 shown in FIG. 19, heating with two shots is usually sufficient in terms of time, but heating is performed as compared with the original sheet before heating. There arises a problem that the transparency of the later sheet is inferior.
[0010]
  Here, the crystalline resin is a resin that has a characteristic that the polymer is crystallized and a part of a long chain polymer is regularly arranged in a certain direction, and the heat resistance, mechanical strength and transparency change. In particular, when the crystallization progresses, the transparency of the resin deteriorates.
[0011]
  As an example of using a bar-type heater other than the conventional ceramic-type far-infrared heater as a heater, a heating apparatus using a high-temperature type sheathed heater has been devised in Japanese Utility Model Publication No. 6-27388. This is a heating device that incorporates a swing mechanism in parallel with the sheet feed direction. However, since it is a long rod-shaped heater, temperature control in the heater longitudinal direction is impossible, and the energy of the heater Since radiation cannot be made uniform, it was necessary to bother to incorporate a rocking mechanism.
[0012]
  Therefore, with such a heating apparatus, partial heating temperature control, which is the most important function in sheet forming, cannot be performed.
[0013]
  In addition, a resin sheet heating method and apparatus using a short-wavelength or medium-wavelength heater having a maximum radiant energy wavelength of 1 to 3 μm as a heater has been proposed (see JP-A-7-276490).
[0014]
  However, since the heater used in this apparatus is integrally formed in the width direction of the resin sheet, there is a problem that the heating temperature in the width direction of the resin sheet cannot be controlled.
[0015]
[Problems to be solved by the invention]
  As described above, in the conventional heating method, in the case of heating a foamed resin sheet in which a thermoplastic resin is impregnated with a foaming agent, it takes a long heating time, and in the case of heating a crystalline resin, Since transparency was inferior, there was a problem in terms of ability and quality.
[0016]
  For example, in the case of a foamed resin sheet in which a thermoplastic resin is impregnated with a foaming agent and subjected to primary foaming, when a secondary foam is formed by reheating in a heating part of a thermoforming machine, a conventional ceramic type is basically used. Heating by far-infrared heaters has limited heating capacity due to the characteristics of the heater, causing only the material surface to rise in temperature, and the temperature inside the material is heated only by heat conduction in the thickness direction. There was a problem that it took.
[0017]
  As a result, it is necessary to reduce the temperature unevenness in the thickness direction by setting the heater temperature low in advance and heating it slowly over a long time at a low temperature, which is a major limitation in terms of productivity. It was.
[0018]
  That is, in the case of a foamed sheet, unlike the case of a non-foamed sheet, the thickness is generally thick, and since the secondary foaming is accompanied by heating, the thickness is further increased, and the heat conduction in the thickness direction becomes worse. Become. Therefore, the temperature inside the material did not rise easily, and the heating efficiency was worse than that of the non-foamed sheet.
[0019]
  In addition, the crystalline resin is inferior in transparency to the original fabric sheet due to heating. For example, in the use as a food container, the contents cannot be clearly seen and the commercial value is lowered.
[0020]
  In addition, there is a problem that heating unevenness occurs at the center portion and the end portion of the resin sheet, a good molding cannot be performed, and the commercial value is lowered.
[0021]
  Therefore, the present invention eliminates the above-mentioned problems, improves the heating efficiency, and at the same time, can heat the resin sheet satisfactorily and uniformly, and can heat the resin sheet using the same. It aims to provide a method.
[0022]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention provides
  [1] In a resin sheet heating apparatus of a thermoforming machine having a sheet heating zone for heating a resin sheet and a sheet forming zone provided on the downstream side of the sheet heating zone, the radiant energy of the heater is added to the heating unit. It has a mid / near infrared region with a maximum wavelength of 1.5 μm to 2.5 μm.Upper heater and lowerA plurality of heater units comprising heaters are arranged in the width direction and the feed direction of the resin sheet, and the heaterunitIsAttached to a heater unit mounting base, the heaterA metal filament as a heating element, a glass tube with this metal filament inside, and a gold reflective film formed on the back surface, and thisThe mothOn the non-heating side of the lath tubeTo be locatedA reflector having a specularity provided;Ceramic heater fixing terminal that supports both ends of the glass tubeMore composedPleaseAndThe heater unit is provided with a plurality of heaters,The temperature of the heater of the heater unit is configured to be individually changeable.
[0023]
  [2] In the resin sheet heating apparatus according to [1] above,WritingThe heater unit mounting bolt is provided with a groove adapted to the shape of the head of the heater unit mounting bolt to prevent the heater unit mounting bolt from rotating together.
[0024]
  [3〕the above〔1In the resin sheet heating apparatus described above, the heater unit has a planar size of 1: 1, 1: 2, 1: 3, 2: 2, or 2: 3. A heating zone is configured in combination.
[0025]
  [4〕the above〔1In the resin sheet heating apparatus described above, the upper and lower heaters are disposed in the heating section, and the arrangement of the lower heater units is changed with respect to the upper heater unit or the heater positions are shifted. It is a thing.
[0026]
  [5〕the above〔4In the resin sheet heating apparatus described above, the heaters of the heater unit are arranged so as to be shifted by a half pitch between the upper heater and the lower heater.
[0027]
  [6〕the above〔4In the resin sheet heating apparatus described above, the heater of the heater unit is arranged in an orthogonal direction with an upper heater and a lower heater.
[0028]
  [7] From [1] to [6The sheet surface temperature is 155 ° C. to 175 ° C. in a state where the expanded polystyrene sheet is kept in a temperature range of 180 ° C. to 220 ° C. within the heating device using the resin sheet heating device according to any one of the above items. While maintaining in the temperature range, secondary foaming is performed and heating is performed.
[0029]
  [8] From [1] to [6The crystalline resin is heated in a state where the temperature in the heating device is maintained within a temperature range of 180 ° C. to 220 ° C. using the resin sheet heating device described in any one of the items.
[0030]
  [9] From [1] to [6The sheet surface temperature is set to 165 ° C. to a temperature in a temperature range of 180 ° C. to 220 ° C. in the heating device by using the resin sheet heating device according to any one of the items Heating is performed while maintaining a temperature range of 190 ° C.
[0031]
  [10] From [1] to [6The amorphous polyethylene terephthalate sheet, which is a crystalline resin but in an amorphous state, is maintained in a temperature range of 180 ° C. to 220 ° C. in the heating device using the resin sheet heating device according to any one of the above items. In this state, the sheet surface temperature is kept in a temperature range of 125 ° C. to 150 ° C. and heated.
[0032]
  [11] From [1] to [6The sheet surface temperature of the polybutylene terephthalate sheet, which is a crystalline resin, is maintained in a temperature range of 180 ° C. to 220 ° C. using the resin sheet heating device according to claim 1. Heating is performed while maintaining a temperature range of 160 ° C to 185 ° C.
[0033]
  [12] From [1] to [6The polypropylene sheet having a foaming ratio of 1.3 to 5, which is a crystalline resin, was maintained in a temperature range of 180 ° C. to 220 ° C. within the heating device, using the resin sheet heating device according to any one of the above items. In this state, the sheet surface temperature is maintained in the temperature range of 170 ° C. to 185 ° C., and then subjected to secondary foaming and heating.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0035]
  FIG. 1 is a configuration diagram of a heater unit showing an embodiment of the present invention, FIG. 1 (a) is a front view of the heater unit, FIG. 1 (b) is a view taken along the line A in FIG. 1 (c) is a cross-sectional view taken along line B in FIG. 1 (a), and FIG. 1 (d) is a cross-sectional view taken along line C in FIG. 1 (a).
[0036]
  As shown in these figures, the heater 1 includes a metal filament 2 that serves as a heating element, a glass tube 3 in which the metal filament 2 is housed, and a reflector provided so as to be positioned on the non-heating side of the glass tube 3. 4 and a ceramic heater fixing terminal 5 that supports both ends of the glass tube 3. Therefore, most of the radiant energy from the metal filament 2 is reflected to the heated portion side by the gold reflecting film 3A on the back surface (reflecting plate side) of the glass tube 3, and further, the reflecting plate is opposite to the heated portion. By arranging 4, the radiant energy is completely reflected to the heated part side. Further, the reflected irradiation energy of the heaters from the opposite sides of the upper heater A and the lower heater B has an effect of reflecting each other, and the heating efficiency is further improved.
[0037]
  Further, a holding member 6 for supporting the heater fixing terminal 5 is provided between the heater fixing terminals 5, and a mounting base 7 is arranged on the holding member 6.InThe reflector 4 and the holding member 6 are fixed by the nuts 9A and 9B through the bolt 8. Further, the wiring 10 is configured to be connected to the metal filament 2.
[0038]
  Thus, the heater 1 is fixed to the mounting base 7 by the bolts 8 and nuts 9A and 9B. However, a groove 7A having the same width as the head of the bolt 8 is cut on the bolt insertion side on the mounting base 7 side. The rotation of the bolt 8 can be suppressed by inserting the head into the groove 7A. Accordingly, the heater alone can be removed by simply loosening the nut 9B on the heater side, so that the workability is excellent.
[0039]
  FIG. 2 is a block diagram of a heater unit showing another embodiment of the present invention, FIG. 2 (a) is a front view of the heater unit, and FIG. 2 (b) is a DD line arrow in FIG. 2 (a). FIG. Here, only the upper heater A is shown, and the same parts as those in FIG. 1 are denoted by the same reference numerals and the description thereof is omitted.
[0040]
  In this embodiment, there are metal mounting brackets 11 arranged on both sides as heater fixing terminals. And the metal attachment bracket 11 is provided in the both ends of the holding member 12, the mounting base 13 is arrange | positioned on the holding member 12, and those center parts are arranged.InThe reflector 4 and the holding member 12 are fixed by the nuts 15A and 15B through the bolt 14. Further, the metal mounting bracket 11 is fixed to the holding member 12 and the reflection plate 4 by bolts 16 and nuts 17. In order to suppress the rotation of the bolt 14, a groove 14 </ b> A having a shape corresponding to the width of the head of the bolt 14 is formed in the mounting base 13. Further, the wiring 18 is configured to be connected to the metal filament 2.
[0041]
  Next, the dimensions of the heater unit (block heater) will be described.
[0042]
  FIG. 3 is an explanatory view of dimensions of various heater units showing an embodiment of the present invention. FIG. 3A is an example in which the heater unit 21 is a square type (one to one) and two heaters 22 are arranged. FIG. 3B shows an example in which the heater unit 21 is a square type (one-to-one) and three heaters 22 are arranged (note that, as shown in FIG. 11 described later, this type is a rectangular type). 3 (c) is an example in which the heater unit 23 is a rectangular type (1 to 2) and two heaters 24 are arranged, and FIG. 3 (d) is a square type (2 to 2). ) In which four heaters 24 are arranged, FIG. 3E shows an example in which the heater unit 26 is a rectangular type (3 to 2) and six heaters 24 are arranged, and FIG. Rectangular type (1 to 3) with 2 heaters 28 Shows location are examples respectively.
[0043]
  Thus, the dimensions of the heater unit (block heater) are basically square and rectangular, and the length of each unit is 1: 1, 1: 2, 2: 2, 3: 2 or 1: 3. Consists of. Further, as shown in FIGS. 3A and 3B, the number of heaters 22 attached to the square type heater unit 21 is easily increased or decreased from two to three (or one). The output can be adjusted. Similarly, as shown in FIG. 3 (c), FIG. 3 (d), FIG. 3 (e) or FIG. 3 (f), the number of heaters 24, 28 can be various.
[0044]
  The present invention can constitute a heating device by combining such heater units (block heaters).
[0045]
  FIG. 4 is a plan view showing the arrangement of block heaters showing the first embodiment of the present invention, FIG. 5 is a plan view showing the arrangement of block heaters showing the second embodiment of the present invention, and FIG. FIG. 7 is a plan view showing the arrangement of block heaters showing the fourth embodiment of the present invention, and FIG. 8 shows the fifth embodiment of the present invention. FIG. 9 is a plan view showing the arrangement of the block heaters according to the sixth embodiment of the present invention, and FIG. 10 is a plan view showing the arrangement of the block heaters according to the seventh embodiment of the present invention. FIG. 11 is a plan view showing the arrangement of block heaters according to the eighth embodiment of the present invention. FIG. 12 is a plan view showing the arrangement of block heaters according to the ninth embodiment of the present invention. Is a plane showing the arrangement of block heaters showing the tenth embodiment of the present invention It is.
[0046]
  According to the first embodiment, as shown in FIG. 4, both the first shot heating zone 31 and the second shot heating zone 32 have the heater unit 21 having two square type heaters 22 shown in FIG. Place on the entire surface. With this arrangement, even when the sheet widths are different, the heating area corresponding to the sheet width can be set finely by turning off the unnecessary heater row at the end, and the sheet feed amount can be reduced. Even if it changes, it is possible to heat only the necessary area by turning off the heater in unnecessary parts according to the feed amount. Thus, even if the sheet width and the feed amount are different, there is an advantage that a necessary heater region can be set finely. Of course, a fine partial heating temperature setting in the sheet heating region is also possible.
[0047]
  According to the second embodiment, as shown in FIG. 5, the second shot heating zone 32 is provided with the heater unit 21 having two square-type heaters 22 shown in FIG. In the central part on the entrance side of the eye heating zone 31, first, only one heater unit 27 having two heaters 28 shown in FIG. 3 (f) is arranged in a direction orthogonal to the sheet flow direction, and further the sheet Four heater units 26 having six heaters 24 shown in FIG. 3E are arranged along the flow direction.
[0048]
  First, on both sides of the central portion, heater units 23 having two heaters 24 shown in FIG. 3C are arranged one by one in a direction perpendicular to the sheet flow direction, and further in the sheet flow direction. 4 heater units 25 each having four heaters 24 shown in FIG. Further, on the outermost sides of both sides, first, heater units 21 having two heaters 22 shown in FIG. 3A are arranged one by one along the sheet flow direction, and further along the sheet flow direction. 3, four heater units 23 each having two heaters 24 shown in FIG. 3C are arranged.
[0049]
  Thus, according to this embodiment, the second shot heating zone 32 is constituted by the heater unit 21, and the first shot heating zone 31 is constituted by a combination of the heater units 21, 23, 25, 27. Yes.
[0050]
  Therefore, the first shot heating zone 31 can be reduced in the number of heater blocks to be controlled by reducing the number of heater blocks to be controlled by providing such a roughly divided heater unit arrangement.
[0051]
  In such an arrangement, the heater division of the first shot heating zone 31 is somewhat larger, but from the viewpoint of formability, the first shot heating zone 31 warms the sheet as a whole, and the second shot heating zone 32 If fine and partial sheet temperature heating control can be performed, a sufficient molded product can be obtained, so there is no functional problem.
[0052]
  According to the third embodiment, as shown in FIG. 6, the number of heaters 24 of the heater units 25 and 26 in the first shot heating zone 31 in the case of the second embodiment (FIG. 5) is halved, and the heater output is reduced. The arrangement is reduced. In that case, the heaters 24 of the heater units adjacent to the heaters 24 of the heater units 25 and 26 are arranged so as to be staggered in a direction orthogonal to the sheet flow direction.
[0053]
  Also in this embodiment, the temperature is finely controlled in the second shot heating zone 32. Therefore, uneven heating can be eliminated with a small number of heaters.
[0054]
  According to the fourth embodiment, as shown in FIG. 7, the upper heater 41 includes both the first shot heating zone 31 and the second shot heating zone 32 as shown in the first embodiment (see FIG. 4). As shown in FIG. 3A, a heater unit 21 having two heaters 22 along the sheet flow direction of a square type is arranged on the entire surface.
[0055]
  On the other hand, the heater arrangement of the lower heater 42 is arranged in a direction orthogonal to the sheet flow direction. That is, the heater arrangement of the lower heater 42 is installed in the vertical direction with respect to the heater arrangement of the upper heater 41. By arranging the upper and lower heaters to be orthogonal, local heating unevenness of the heaters can be eliminated from each other.
[0056]
  According to the fifth embodiment, as shown in FIG. 8, similarly to the fourth embodiment, the upper and lower heaters are arranged so as to be perpendicular to each other. The upper heater 43 has the same heater unit arrangement as that of the second embodiment (FIG. 5). On the other hand, the lower heater 44 is disposed in a direction orthogonal to the sheet flow direction so as to be generally orthogonal to the heater arrangement of the upper heater 43.
[0057]
  That is, the first shot heating zone 31 has a heater unit 27 having two heaters 28 at the center, a heater unit 23 having two heaters 24 on both sides thereof, and two heaters 22 on the outermost sides. Nine heater units 21 each having the same are arranged in a direction perpendicular to the sheet flow direction. Here, the heater used is changed in the first and second shots. Even in this embodiment, local heating unevenness of the heaters can be eliminated.
[0058]
  According to the sixth embodiment, as shown in FIG. 9, the heater arrangement of the upper heater 45 of the first shot heating zone 31 is the same as that of the third embodiment (FIG. 6). In contrast to this heater arrangement, the heater arrangement in the first shot heating zone 31 of the lower heater 46 is arranged so as to alternate with the heater arrangement of the upper heater. Note that the arrangement of the upper heater 45 and the lower heater 46 of the sheet carry-in entrance of the first shot heating zone 31 is the same.
[0059]
  As described above, since the positions of the opposed heaters are shifted in a certain area in the first shot heating zone, the heating unevenness can be eliminated.
[0060]
  According to the seventh embodiment, as shown in FIG. 10, the upper heater 47 and the lower heater 48 of the second shot heating zone 32 are arranged so as to be orthogonal to each other. The heater arrangement of the upper heater 47 of the first shot heating zone 31 is the same as that in the third embodiment (FIG. 6). In contrast to this heater arrangement, the heater arrangement in the first shot heating zone 31 of the lower heater 48 is arranged so as to alternate with the heater arrangement of the upper heater. Note that the arrangement of the upper heater 45 and the lower heater 46 of the sheet carry-in entrance of the first shot heating zone 31 is the same. Even in this embodiment, local heating unevenness of the heaters can be eliminated.
[0061]
  According to the eighth embodiment, as shown in FIG. 11, the heater arrangement is characterized in that the heater pitch in the heater width direction is arranged in a state where the heater pitch is shifted by half a pitch from each other. That is, in the upper heater 49, as shown in the first embodiment (FIG. 4), the heater unit 21 having the two heaters 22 is disposed on the entire surface. By arranging the heater unit 21 'having the three heaters 22' shown in (b) and arranging the heater unit 21 having the other two heaters 22 in the others, the heater pitch is shifted by half a pitch from each other vertically. I am doing so. Even in this embodiment, local heating unevenness of the heaters can be eliminated.
[0062]
  According to the ninth embodiment, as shown in FIG. 12, a rod-shaped heater 29 is arranged in the first shot heating zone 31 with the positions of the upper and lower heaters 51, 52 being shifted by a half pitch in the direction perpendicular to the sheet flow. And prevent uneven heating. In addition, the second shot heating zone 32 is installed in a direction perpendicular to the heater arrangement of the first shot heating zone 31, and the heating unevenness of the first shot heating zone 31 and the second shot heating zone 32 is eliminated. To do.
[0063]
  According to the tenth embodiment, as shown in FIG. 13, the heater arrangement in the first shot heating zone 31 and the second shot heating zone 32 is inverted 90 ° relative to the case of the ninth embodiment (FIG. 12). It arrange | positions in the made state, It is characterized by the above-mentioned. That is, the arrangement of the rod-shaped heaters 29 is arranged so as to be perpendicular to the sheet flow direction, and the arrangement of the rod-shaped heaters 29 is arranged in a state shifted by a half pitch between the upper heater 53 and the lower heater 54. Even in this embodiment, local heating unevenness of the heaters can be eliminated.
[0064]
  As described above, the heater used in the present invention has a heating element temperature as high as 800 ° C. to 1600 ° C., and the wavelength range emitted from the heating element is as short as 1.5 to 2.5 μm. It is a short wavelength region. A heater having such a short wavelength is used for heating the resin. As a characteristic of this heater, energy is penetrated and absorbed deep inside the material, and heating from the inside of the material can be performed.
[0065]
  Therefore, a uniform heating effect up to the inside of the material can be expected as compared with a far-infrared heater having a maximum heating element temperature of about 300 ° C. to 500 ° C. in which most of the energy is absorbed only on the material surface.
[0066]
  As a result, in the case of a foam sheet, the energy penetrates into the material and heats it up so that heating in a short time is possible, and the temperature inside the material is higher than before, increasing the internal foaming ratio, As a result, it is possible to approach an ideal sandwich structure with light weight and high rigidity.
[0067]
  Further, since the internal heating can be sufficiently performed without increasing the material surface temperature, the material surface roughness is improved as compared with the conventional far-infrared heater.
[0068]
  (1) As a first specific example of the present invention, as shown in FIG. 14, the heating rise performed in a state where the expanded polystyrene sheet (PSP) of company A is maintained in a temperature range of 180 ° C. to 220 ° C. in the heating apparatus. The temperature test result is shown.
[0069]
  The conventional far-infrared heater required 17 to 18 seconds to heat up to around the molding temperature of 170 ° C. However, the heating device of the present invention can be heated in about 4 seconds, and the heating time is significantly increased. Will be shortened.
[0070]
  (2) FIG. 15 shows the result of measuring the foam thickness of the material when heated by the heating device of the present invention. Similarly, in the state where the temperature inside the heating device is kept in the range of 180 ° C. to 220 ° C. Under the conditions of output, top: 90%, bottom: 100%, a secondary sheet thickness with a sufficient thickness (5 mm or more) having an excellent surface state can be obtained in 4 seconds. In addition, a secondary sheet thickness of a sufficient thickness (5 mm or more) with excellent surface condition was obtained in 5 seconds under the conditions of heater output, upper: 60%, lower: 70%. In addition, the thickness of the obtained secondary sheet is thicker than in the case of heating with a conventional far-infrared heater shown in FIG. In the far-infrared heater, as the heater temperature is increased, the favorable thickness of the surface state tends to gradually decrease.
[0071]
  In the conventional far infrared heater, if the heater temperature is raised to 350 ° C., it can be heated in about 5 seconds, but the thickness of the secondary sheet can only be about 4 mm, and if further heated, it becomes a little thicker, The surface of the sheet becomes defective.
[0072]
  Even if the heater temperature is lowered in order of 300 ° C. → 250 ° C. → 200 ° C., the thickness of the secondary sheet cannot be increased to 5 mm or more, and more heating time is required.
[0073]
  (3) As a second specific example of the present invention, a polypropylene sheet (PP sheet) that is a crystalline resin, a polybutylene terephthalate sheet (PBT sheet), and an amorphous polyethylene terephthalate sheet that is a crystalline resin but in an amorphous state (A-PET sheet) is heated in a state where the temperature inside the heating device is kept in the range of 180 ° C. to 220 ° C., and the result of comparative measurement of the change in sheet transparency after the heating is shown in FIG. Although the effect varies somewhat depending on the type of resin or manufacturer, the material transparency after heating is generally increased by using the middle / near infrared heater according to the present invention compared to the case of heating by a conventional far infrared heater in each material. It was confirmed that it was excellent.
[0074]
  Furthermore, as shown in FIG. 17, in the case of heating a solid sheet, when a crystalline resin such as PP, PET, PBT is heated, the radiant energy wavelength of the heater absorbed at the polymer level is short. As a result, the molding speed is reduced and the crystal structure of the resin is hardly affected. As a result, the sheet can be heated in a state where the transparency of the sheet is maintained, so that a molded article having excellent transparency can be obtained.
[0075]
  FIG. 18 illustrates the generally defined wavelength ranges of heater radiant energy in the near-infrared region, mid-infrared region, and far-infrared region.
[0076]
    Furthermore, as a specific example of the present invention, a polypropylene sheet having a foaming ratio of 1.3 to 5, which is a crystalline resin, has a sheet surface temperature of 170 ° C. in a temperature range of 180 ° C. to 220 ° C. in the heating apparatus. While maintaining the temperature range of ˜185 ° C., the secondary foaming is performed.
[0077]
  That is, the result of the heating temperature increase test in a state where the foamed polypropylene sheet (foamed PP sheet) of company B is maintained in a temperature range of 180 ° C. to 220 ° C. in the heating device is shown. here,
  (1) Material: foamed PP sheet, thickness 1.3 mm, primary expansion ratio about 1.5 times
  (2) The heating result is as follows.
[0078]
    Time (second) Temperature (℃)
      5 132
    10 143
    15 157
    20 164
    25 173
    30 182
  Conventional far-infrared heaters require a heating time of 40 seconds to 45 seconds, and even if the heater temperature is raised to shorten the heating time, the surface becomes rough and impossible, By using, good heating in 30 seconds or less became possible.
[0079]
  In addition, since heating in a short period of time is possible, the amount of sheet sagging is reduced, and wrinkles that occur due to sagging in the molded product do not occur.ButIt was also confirmed that there was an advantage that it was easier to obtain.
[0080]
  In addition, unprecedented heating efficiency is exhibited by using the same technology for all foamed resin sheets such as foamed PET sheets (polyethylene terephthalate), and resin sheets impregnated with foamed materials. Molding can be easily performed.
[0081]
  The present invention is not limited to the above-described embodiments, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.
[0082]
【The invention's effect】
  As described above in detail, according to the present invention, the following effects can be obtained.
[0083]
  (A) Since the heater region in the width direction and the feeding direction of the resin sheet can be set finely, the temperature of the resin sheet region can be finely controlled.
[0084]
  Moreover, most of the energy radiated from the metal filament is reflected by the gold reflective film on the back side of the glass tube to the heated part, and a reflector is placed on the opposite side of the heated part. There is an effect that the radiant energy is reflected to the heated portion side.
[0085]
  (B) Since the heating device is not provided in the mold, but is disposed on the downstream side of the sheet molding zone in which the mold is disposed, the resin sheet can be directly heated. And by providing a reflecting plate, more efficient heating can be performed.
[0086]
  More specifically,
  (1The present inventionAccording to this resin sheet heating apparatus, the heating efficiency can be improved and the temperature distribution of the resin sheet can be set finely, so that the sheet can be heated satisfactorily.
[0087]
  (2The present inventionAccording to the resin sheet heating apparatus, most of the radiant energy from the metal filament is reflected by the gold reflective film on the back of the glass tube to the heated part, and a reflector is placed on the opposite side of the heated part. As a result, the energy is completely reflected to the heated part side, and the reflected irradiation energy of the heaters from the opposite sides of the upper heater and the lower heater also reflects each other, further improving the heating efficiency. Can be planned.
[0088]
  (3The present inventionAccording to the resin sheet heating apparatus, it is possible to prevent the heater unit mounting bolts from turning around and to detach the heater unit from one side.
[0089]
  (4The present inventionAccording to the resin sheet heating apparatus, a necessary heater region can be set finely even if the sheet width and the feed amount are different.
[0090]
  (5The present inventionAccording to this resin sheet heating apparatus, by setting the temperature of the heater of the heater unit to be individually changeable, it is possible to perform fine partial heating temperature setting in the sheet heating region.
[0091]
  (6The present inventionAccording to the resin sheet heating apparatus, local heating unevenness of the heater can be eliminated by changing the arrangement of the upper and lower heaters or by shifting the positions thereof.
[0092]
  (7The present inventionAccording to this resin sheet heating apparatus, the uneven heating of the resin sheet can be eliminated by arranging the heaters of the heater unit so as to be shifted by a half pitch between the upper heater and the lower heater.
[0093]
  (8The present inventionAccording to the resin sheet heating apparatus, the heater of the heater unit is arranged in the orthogonal direction between the upper heater and the lower heater, thereby eliminating local heating unevenness of the sheet.
[0094]
  (9The present inventionAccording to the method for heating a foamed polystyrene sheet, the foaming thickness is large while maintaining a good surface state, and the material internal foaming ratio can be increased.
[0095]
  (10The present inventionAccording to this method for heating a crystalline resin sheet, it is possible to obtain excellent transparency in which the transparency after heating is close to that of the original fabric sheet.
[0096]
  (11The present inventionAccording to the method for heating a polypropylene sheet, it is possible to obtain excellent transparency in which the transparency after heating is close to that of the original fabric sheet.
[0097]
  (12The present inventionAccording to the method for heating an amorphous polyethylene terephthalate sheet, it is possible to obtain excellent transparency in which the transparency after heating is close to that of the original sheet.
[0098]
  (13The present inventionAccording to the method for heating a polybutylene terephthalate sheet, it is possible to obtain excellent transparency in which the transparency after heating is close to that of the original sheet.
[0099]
  (14The present inventionAccording to the method for heating a foamed polypropylene sheet, good heating in 30 seconds or less became possible.
[0100]
  In addition, since heating in a short time is possible, the amount of sheet sagging is reduced, and wrinkles generated by sagging in the molded product do not occur, and a good molded product can be obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a single heater (unit) showing an embodiment of the present invention, FIG. 1 (a) is a front view of the heater unit, and FIG. 1 (b) is an arrow A in FIG. FIG. 1C is a cross-sectional view taken along line B in FIG. 1A, and FIG. 1D is a cross-sectional view taken along line C in FIG.
FIG. 2 is a configuration diagram of a heater unit (unit) showing another embodiment of the present invention, FIG. 2 (a) is a front view of the heater unit, and FIG. 2 (b) is D in FIG. 2 (a). FIG.
FIG. 3 is an explanatory view of dimensions of various heater units showing an embodiment of the present invention, and FIG. 3 (a) is an example in which the heater unit is a square type (one to one) and two heaters are arranged; FIG. 3B shows an example in which the heater unit is a square type (one to one) and three heaters are arranged, and FIG. 3C shows that the heater unit is a rectangular type (one to two) and two heaters are arranged. Fig. 3 (d) shows an example in which the heater unit is a square type (2 to 2) and four heaters are arranged. Fig. 3 (e) shows a rectangular heater unit (3 to 2) and a heater. FIG. 3F shows an example in which six heaters are arranged, and FIG. 3F shows an example in which the heater unit is a rectangular type (1 to 3) and two heaters are arranged.
FIG. 4 is a plan view showing an arrangement of block heaters according to the first embodiment of the present invention.
FIG. 5 is a plan view showing an arrangement of block heaters showing a second embodiment of the present invention.
FIG. 6 is a plan view showing an arrangement of block heaters according to a third embodiment of the present invention.
FIG. 7 is a plan view showing an arrangement of block heaters according to a fourth embodiment of the present invention.
FIG. 8 is a plan view showing an arrangement of block heaters according to a fifth embodiment of the present invention.
FIG. 9 is a plan view showing an arrangement of block heaters according to a sixth embodiment of the present invention.
FIG. 10 is a plan view showing an arrangement of block heaters according to a seventh embodiment of the present invention.
FIG. 11 is a plan view showing an arrangement of block heaters according to an eighth embodiment of the present invention.
FIG. 12 is a plan view showing an arrangement of block heaters according to a ninth embodiment of the present invention.
FIG. 13 is a plan view showing an arrangement of block heaters according to a tenth embodiment of the present invention.
FIG. 14 is a diagram showing a heating temperature rise characteristic of a foam PSP by the heating device of the present invention.
FIG. 15 is a view showing a heating test result by the heating apparatus of the present invention.
FIG. 16 is a diagram showing a heating test result by a conventional far infrared heater.
FIG. 17 is a diagram showing the results of a transparency comparison test after heating various materials.
FIG. 18 is a diagram showing an electromagnetic wave spectrum (wavelength, frequency and photon energy).
FIG. 19 is a diagram showing an outline of a continuous sheet thermoforming machine.
[Explanation of symbols]
  1,22,22 ', 24,28 Heater
  2 Metal filament
  3 Glass tube
  3A gold reflective film
  4 reflectors
  5 Heater fixing terminal
  6,12 Holding member
  7,13 Mounting base
  7A, 14A groove
  8, 14, 16 volts
  9A, 9B, 15A, 15B, 17 Nut
  10, 18 wiring
  11 Metal mounting bracket
  21, 21 ', 23, 25, 26, 27 Heater unit
  29 Bar heater
  31 First shot heating zone
  32 Second shot heating zone
  A, 41, 43, 45, 47, 49, 51, 53 Upper heater
  B, 42, 44, 46, 48, 50, 52, 54 Lower heater

Claims (12)

In a heating apparatus for a resin sheet of a thermoforming machine having a sheet heating zone for heating a resin sheet and a sheet forming zone provided on the downstream side of the sheet heating zone, the heating portion has a maximum wavelength of radiation energy of the heater. A plurality of heater units composed of an upper heater and a lower heater having a middle / near infrared region of 1.5 μm to 2.5 μm are arranged in the width direction and the feed direction of the resin sheet, and the heater unit is attached to a heater unit mounting base. is specular said heater and metal filaments as a heat generator, and interior of the metal filaments, and glass tube gold reflective film is formed on the rear surface, provided so as to be positioned in the anti-heating side of 該Ga Las tube a reflector having a gender, with are formed of a ceramic heater fixed terminal that supports both ends of the glass tube, the Hitayu A resin sheet heating apparatus , wherein a plurality of the heaters are arranged in a knit, and the temperature of the heater of the heater unit can be individually set and changed. In the heating apparatus of the resin sheet according to claim 1 wherein, prior to Kihi Tayunitto mounting frame, to prevent the co-rotation of the heater unit mounting bolts by having a groove adapted to the shape of the head of the heater unit mounting bolts A resin sheet heating apparatus. 2. The apparatus for heating a resin sheet according to claim 1 , wherein the heater unit has a planar size of 1: 1, 1: 2, 1: 3, 2: 2, or 2: 3. A heating device for a resin sheet, wherein a heating zone is configured by combining sizes. 2. The resin sheet heating apparatus according to claim 1 , wherein upper and lower heaters are disposed in the heating unit, and the arrangement of the lower heater units is changed or the heater positions are shifted with respect to the upper heater unit. A resin sheet heating device. 5. The resin sheet heating apparatus according to claim 4 , wherein the heaters of the heater unit are arranged so as to be shifted by a half pitch between the upper heater and the lower heater. 5. The resin sheet heating apparatus according to claim 4 , wherein the heater of the heater unit is arranged in an orthogonal direction between an upper heater and a lower heater. The sheet surface temperature is 155 ° C in a state where the expanded polystyrene sheet is kept in a temperature range of 180 ° C to 220 ° C in the heating device using the resin sheet heating device according to any one of claims 1 to 6. To 175 ° C., second foaming and heating while maintaining the temperature range. A crystalline resin is heated using the resin sheet heating apparatus according to any one of claims 1 to 6 while being kept in a temperature range of a heating apparatus internal temperature of 180 ° C to 220 ° C. Resin sheet heating method. The sheet surface temperature in a state where the polypropylene sheet, which is a crystalline resin, is maintained in a temperature range of 180 ° C to 220 ° C in the heating device using the resin sheet heating device according to any one of claims 1 to 6. Is heated in a temperature range of 165 ° C to 190 ° C. Using the heating apparatus for a resin sheet according to any one of claims 1 to 6 , an amorphous polyethylene terephthalate sheet that is a crystalline resin but is in an amorphous state is heated at an internal temperature of 180 ° C to 220 ° C. A method for heating a resin sheet, comprising heating while maintaining a sheet surface temperature in a temperature range of 125 ° C. to 150 ° C. while maintaining the temperature range. Using the resin sheet heating device according to any one of claims 1 to 6 , the polybutylene terephthalate sheet, which is a crystalline resin, is kept in a temperature range of 180 ° C to 220 ° C in the heating device. A method for heating a resin sheet, comprising heating the sheet surface temperature in a temperature range of 160 ° C to 185 ° C. Using the heating apparatus for a resin sheet according to any one of claims 1 to 6, a polypropylene sheet having a foaming ratio of 1.3 to 5 that is a crystalline resin is heated to a temperature of 180 to 220 ° C in the heating apparatus. A method for heating a resin sheet, characterized in that the sheet surface temperature is kept in a temperature range of 170 ° C. to 185 ° C. while being kept in a range, and secondarily foamed and heated.

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