Injection box and drawing device equipped with injection box

Abstract

To provide an improved jetting box, in particular a jetting box comprising a replaceable ventilation tube, and a stretching device equipped with the jetting box.SOLUTION: The improved jetting box has an interior space (2) formed by a plurality of side walls spaced apart from each other, a bottom wall, and a vent wall (5) spaced apart from the bottom wall, and a plurality of vent openings (7) spaced apart from each other are formed in the vent wall. Each of the plurality of projections (13) formed on the vent wall of the jet box protrudes at least a certain height from a portion of the vent wall adjacent to the projection or from the top or an apex (5a) of the vent wall, and a vent opening is formed in the region of the projection protruding from the top or apex of the vent wall and / or a pair of lateral projecting edges of the vent wall, provided opposite each other in a transverse direction of the jet box, overlap the side walls of the injection box and are located on the outer edge of the interior space of the injection box.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The invention relates to a jet box as defined in the preamble of claim 1 and to a drawing device comprising the jet box. [Background technology]

[0002] For example, a nozzle box for blowing temperature-controlled air onto a thin resin film is useful for the heating or cooling process of a long ribbon-like material in the form of a thin resin film, particularly during the production of the thin resin film. The nozzle box, which serves as an air jet pipe arranged transversely to the molecular chain orientation (stretching) of the long ribbon-like material, which is usually perpendicular to the drawing direction of the long ribbon-like material, is usually arranged above and / or below the long ribbon-like material.

[0003] For example, a plurality of jet boxes arranged above or below the long strip material are connected to form a so-called interchangeable vent pipe that forms a ventilation area. The interchangeable vent pipe is arranged across the width of the long strip material and beyond the width of the long strip material, and includes associated jet boxes having a length of 1.5 m, 3 m, 5 m, 7.5 m or less, or for example, a length of 10 m or less and a length of 10 m or more.

[0004] In the pre-heating zone of the stretching machine, for example, the air is usually heated and warmed according to the purpose of use, so that the air and the resin film are heated, via a replaceable vent pipe or a heater / ventilation position adjustment valve. When a replaceable vent pipe is used in the cooling zone, the film is cooled through the correspondingly cooled air. The replaceable vent pipe usually draws in ambient air and blows it onto the film. A mixture of ambient air and warm air can also be used to further cool the air in the pre-stage zone. In the ventilation state, air (lower than the film temperature) can also be sprayed onto the film.

[0005] The jet box constitutes a closed type (ventilation device) or open type (using ambient air) exchange ventilation pipe. In some cases, a closed type ventilation device is used to introduce air from a lateral ventilation device into the inner space of the jet box to heat the long strip material or especially the resin film. A number of outlet openings or jet openings formed in the jet box eject the air in the jet box towards the long strip material / resin film. The air introduced into the jet box is ejected above or below the jet box and then collected between the jet boxes. For example, a number of suction boxes or free spaces provided above or below the jet boxes can suck in the ejected air, heat it again in the closed device, and supply it again to the jet box via the ventilation device. For example, in a heating ventilation state, the air is circulated multiple times using multiple heat exchangers.

[0006] In a preferred variant embodiment of the invention, in particular in the transverse stretching machine or transverse stretching oven of a sequential thin-film stretching apparatus or in a simultaneous thin-film stretching apparatus, a replaceable vent pipe consisting of a jet box is employed.

[0007] A jet box suitable for the above purpose, which comprises a number of air supply chambers arranged in the longitudinal direction in the jet box and connected to each other, is known, for example, from the patent document EP 1 299 636. A vent wall, jet wall, vent surface or jet surface, in which a number of outlet openings, vent openings or outflow openings for the air jetting out are usually provided in the jet box itself, and a number of adjacent and parallel hole-like vent openings are often formed in the jet box along a number of rows. A jet box with vent openings in the vent wall or jet wall arranged in the direction of the long strip of material (length of the resin film) is usually assembled in a drawing device above and below the long strip of material. A number of jet boxes with a number of hole-like outlet openings or jet openings formed in various geometric shapes have also been proposed.

[0008] The outlet openings formed on the jet outlet surface of the jet wall of the air jet device disclosed in Patent Document 2 may be provided in a number of specific arrangements. The jet inner surfaces (inner surfaces opposite to the jet outlet surfaces) may be provided with a number of cylindrical protrusions to extend the jet length and achieve a specific effect.

[0009] For production engineering reasons, it is necessary to construct or form an elongated jet box from at least two or more parts (jet box segments) in order to assemble the longitudinally arranged jet boxes in the drawing device.

[0010] In particular, during the manufacture and stretching (particularly during the wet process) of the resin thin film used as the battery partition plate, a series of additives, particularly oil, are blended into the stretched resin thin film material, so that when the resin thin film passes through a heating furnace during the stretching process, oil seeps out and separates from the moving long strip material. As a result, oil drips or flows down from the resin thin film onto the surface of the injection box, which is located below the moving resin thin film, and adheres to the ventilation wall area of ​​the injection box. The oil adhering to the ventilation wall area may pass through the outflow opening and reach the injection path.

[0011] However, the oil does not necessarily flow out from the outlet openings, but may enter the injection box through all possible openings, recesses or gaps, such as the flanges and the joints of the bulkheads.

[0012] The oil flowing inside the injection box is eventually partially reabsorbed into the circulating air during operation and discharged together onto the surface of the resin film, which has the disadvantage that the oil adheres to the surface of the resin film to be stretched, causing unexpected adverse effects on the quality of the resin film. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] European Patent Publication No. 0907476B1 [Patent Document 2] Chinese Patent No. 106003679B Summary of the Invention [Problem to be solved by the invention]

[0014] SUMMARY OF THE PRESENT EMBODIMENT It is therefore an object of the present invention to provide an improved jet box, and in particular to provide a drawing machine having a jet box which constitutes a replaceable vent pipe. [Means for solving the problem]

[0015] The problem of the invention is solved by a jet box having the features of claim 1, while the problem of a drawing device with a jet box forming a replaceable vent pipe is solved by the features of claim 13. Advantageous configurations of the invention are set out in the dependent claims.

[0016] The solution according to the invention is characterized by means of a particularly simple construction which prevents the migration of oil from the region of the injection openings into the interior of the injection box. The gas treatment medium (usually in the form of air) emerging from the injection openings absorbs the oil or oil droplets adhering to the injection box and transports them in the direction of the film movement, so that it is an object of the invention to avoid the adhesion of harmful oil pollutants to the resin film. The term "film" in this document is intended to include any possible full length strip of material, regardless of whether it is abbreviated as resin film, film or film etc.

[0017] The present invention provides a method for preventing the adhesion of harmful oil contaminants by providing a suitable specially shaped protrusion, annular vent opening, or formed ridge, and a pair of side flanges overlapping the side walls of the injection box and facing transversely of the injection box are provided on the vent wall at the periphery of the injection box's internal space.

[0018] In a preferred embodiment of the invention, the protrusions can be formed in the vent wall of a preferred bulkhead of the injection box by a simple embossing process, i.e., by embossing the bulkhead or by a modified deep drawing process. In other words, the injection box and associated vent openings with protrusions can be produced in one simultaneous punching and / or embossing process.

[0019] The outer boundary of the vent projection is preferably conical, tapering at least slightly from the plane or outside of the vent wall in the direction of the projection, although the shape of the projection may be of a different form. In particular, it is preferred to provide a circular vent opening in a frustoconical projection having a flat projection end face, for example a circular or elliptical vent opening in an annular end face with a dimensional width that may vary between 0.5 mm and 5 mm.

[0020] The somewhat inclined angle formed at the outer boundary of the annular projection of the vent opening, i.e. the opening angle of the cone, forms a minimal angle with respect to a perpendicular line to the vent wall, and the annular projection is not formed cylindrically. A convenient inclined acute angle that provides the advantages of the embossing process is 89.75° or less. The inclined acute angle of the annular projection may also be less than 89.75°, e.g., 45° or less. All angle values ​​between the above angles may also be suitably used.

[0021] In a preferred embodiment of the present invention, the ventilation wall of the injection box in which the ventilation openings are provided is formed continuously in the transverse direction of the injection box, and is not a combination structure in which a plurality of ventilation wall portions are adjacent to each other in the longitudinal direction of the injection box, arranged in parallel, and connected to each other laterally. A gap-like gap is formed at the side protruding edge of the ventilation wall composed of multiple parts of the injection box, and it is possible to prevent the intrusion of oil into the injection box through the gap-like gap and the transport of oil by air supplied from the multiple ventilation openings in the direction of the resin thin film.

[0022] It is preferred that the outer periphery of the vent wall extending laterally of the injection box is provided with a tongue or flange forming an end wall, and that the flange protruding from the vent wall overlapping outwardly with the adjacent side wall of the injection box prevents oil from entering the injection box.

[0023] Only in the case of an elongated jet box (in addition to a number of wall portions which are preferably overlapping) consisting of at least two or more parts (jet box pieces) assembled in the longitudinal direction, a specific protruding vent wall edge is added to the vent wall, so that no gap is formed connecting to the inside of the jet box from the top or outside (a gap formed on the top or surface of the vent opening through which oil can penetrate into the jet box).

[0024] In the present invention, the projection of the ventilation wall of the injection box and its height can be set to a small dimension.

[0025] Other than a single vent opening, for example two (or more) vent openings may be formed in a protruding plateau-like protrusion of the vent wall, in other words it is not necessary to form a separate individual protrusion for each vent opening.

[0026] Further advantages, details and features of the invention will become apparent from the following description of the embodiments, which are given in the drawings, in which: [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic perspective view of an injection box according to the present invention; [Diagram 2] Cross-sectional view of the injection box in Fig. 1 [Diagram 3] FIG. 1 is an enlarged cross-sectional view showing the ventilation openings of the protrusions formed in the ventilation wall of the injection box; [Figure 4] FIG. 1 is a perspective view showing ventilation openings formed in two adjacent protrusions. [Diagram 5] Cross-sectional view of a protrusion formed perpendicular to a ventilation wall [Figure 6a] Cross-sectional view of the tongue protruding from the injection box before it is mated with the other injection box [Figure 6b] A cross-sectional view of the tongue member of Figure 6a fitting into the edge of the ventilation wall of the other injection box. [Figure 6c] FIG. 6b is a cross-sectional view of the tongue member of FIG. 6b fully fitting into the edge of the vent wall of the mating injection box to close the gap formed between the folded edges. [Figure 7a] FIG. 1 is a partial perspective view of elongated vent openings spaced apart in the transverse direction of the injection box; [Figure 7b] FIG. 1 is a partial perspective view of a ventilation opening formed at an angle to the transverse direction of the injection box; [Figure 7c] FIG. 1 is a partial perspective view of a ventilation opening formed perpendicular to the transverse direction of the injection box; [Figure 8] FIG. 1 is a perspective view of a replaceable vent pipe with four jet boxes according to the invention arranged parallel to one another and perpendicular to the direction of withdrawal of the strip of material. [Figure 9] A cross-sectional view in which multiple injection boxes are arranged perpendicular to the drawing direction of the resin film, above and below the resin film, and a discharge container and / or a capture container for collecting oil seeping out from the resin film are arranged between the lower injection boxes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] A first embodiment of the injection box of the present invention in which a tongue member is provided so as to be able to be assembled in an assembly area on the end face of the injection box will be described below.

[0029] The injection box 1 has a longitudinal length L, a transverse length Q and a height H. It is not essential that the cross-sectional shape of the injection box 1 has a rectangular cross-section.

[0030] In the illustrated embodiment, the injection box 1 has a bottom wall (bottom surface) 3a and two side walls 3b arranged perpendicular to the bottom wall 3a and parallel to each other at a certain distance from each other, facing each other. A ventilation wall or injection wall 5 is provided above the bottom wall 3a with a distance H therefrom.

[0031] A pair of side walls 3b, a bottom wall 3a and a ventilation wall or injection wall 5 are formed surrounding an internal space 2, also called a supply chamber 4, which supplies air, and the air in the internal space 2 is discharged through a number of ventilation openings 7. In the illustrated embodiment, the injection box 1 has a rectangular cross-sectional shape, but it may be formed with other cross-sectional shapes. For example, it is also possible to form a structure in which the curved side wall 3b is continuously connected to the curved bottom wall 3a, as long as both edges of the side wall 3b, which are clearly defined in the cross-sectional view, are continuously connected to the bottom wall 3a. In short, the specific cross-sectional shape of the injection box 1 is not important to the present invention.

[0032] The ventilation openings 7 formed in the ventilation or jet wall 5 arranged in the longitudinal direction L are also called jet openings, jetting openings or normal openings 7, even if they have a special opening shape (e.g. circular, rectangular, square openings, etc.). In the illustrated embodiment, the ventilation openings 7 are formed in the ventilation or jet wall 5 spaced apart from one another in the longitudinal direction L and also in the arrangement R direction spaced apart in the transverse direction Q. It is not necessary to arrange the ventilation openings 7 in a predetermined arrangement R direction, since the shape and arrangement of the ventilation openings 7 can be set in the longitudinal direction L and the transverse direction Q in any manner different from the illustrated embodiment.

[0033] As in the embodiment shown in FIG. 1, the injection box 1 comprises or is provided with two injection box pieces 1a, 1b divided in the longitudinal direction L, and a pair of opposing end faces forming a boundary surface 9 of the injection box pieces 1a, 1b are at least indirectly fixed and / or connected, in particular so that the boundary surface 9 can be extended by assembling the injection box 1 on site to extend its overall length.

[0034] FIG. 2 shows a schematic cross-section of the injection box 1 in a transverse direction Q perpendicular to the longitudinal direction L.

[0035] The vent openings 7 shown in Figure 2 are provided or formed in the vent or jet wall 5 in the form of or in the region of the protrusions 13. It is preferred to manufacture the jet box 1, and in particular the vent or jet wall 5, suitably formed from a partition, in particular a metallic partition, to form the vent / jet openings 7 and associated protrusions 13 by simultaneous embossing and stamping steps.

[0036] The embodiment of FIG. 2, the enlarged cross-sectional view of a projection 13 of the ventilation opening 7 of FIG. 3 and the extracted perspective view of two projections 13 of FIG. 4 show a circumferential outer boundary wall 15 which is formed conically or at least slightly conically.

[0037] The outer boundary wall 15 in the illustrated embodiment forms a truncated cone shape converging upwards from the vent wall 5 or the top surface 5a of the vent wall 5. The actual vent opening 7 is formed by an annular opening edge 17, which constitutes a rounded closing edge free of machining burrs on the peripheral edge. During the manufacture of the strip of material, especially the thin film, it is important to provide the opening edge 17 with a "burr-free" closing edge to prevent the thin film from coming into contact with the metal machining burrs on the annular opening edge 17 of the vent opening 7, which may fray, wear, damage, break or crack the thin film. In the illustrated embodiment, the opening edge 17 is formed or arranged at least approximately parallel to the upper or top surface 5a of the injection wall 5. However, it is not necessary to arrange the opening edge 17 parallel to the upper or top surface 5a of the injection wall 5. Even in a cross section perpendicular to the top surface 5a, the opening edge 17 may be curved, for example converging at a gradually decreasing angle towards the vent opening 7 of the upper or top surface 5a.

[0038] It is preferable to arrange at least the opening edge 17 to be inclined at a small angle relative to the upper surface (upper wall) or top surface 5a of the injection wall 5. For example, the opening edge 17 is formed inclined at a small angle of less than 45°, less than 30°, 25°, 20°, 15°, 10° or less than 5° relative to the plane of the top surface 5a from the outer edge of the opening edge 17 toward the actual ventilation opening 7.

[0039] For example, the protrusion 13 can be formed with a very small height H (FIG. 3) between 0.5 mm and 10 mm. The width of the annular opening edge 17 can also be formed with a similar size.

[0040] When forming the protrusions 13 in the embossing process, it is preferable to form slightly diverging cone-shaped protrusions 13. The injection mold can be easily removed from the cone-shaped protrusions 13, and forming the cone-shaped protrusions 13 is also advantageous when molding the vent wall 5 with resin. For example, particularly when manufacturing the vent wall or jet wall 5 by the embossing and punching processes of a metal partition wall or manufacturing the resin vent wall or jet wall 5 by resin injection molding, it is preferable to manufacture the protrusions 13 integrally with or simultaneously with the vent opening 7 in a single processing step.

[0041] 5 shows an annular outer boundary wall 15 formed in a substantially cylindrical shape different from that of FIG. 3, and in this embodiment, it is also preferable to form the boundary wall 15 at least slightly conical, in particular slightly conically diverging from the top surface 5a of the injection wall 5. The inclination acute angle α (the inclination angle between the conically inclined boundary wall 15 shown in FIG. 3 and the plane of the ventilation wall 5) is advantageously less than 90°, for example less than 89.75°, in particular less than 89.5°, 89.25°, 89°, 88°, 87°, 86°, 85°, 84°, 83°, 82°, 81° or 80°, which avoids a cylindrical shape. The inclination acute angle α is preferably less than 60°, 50°, 45° or 40°, and is formed on the surface of the ventilation wall 5 with a large cone radius.

[0042] 6a, 6b and 6c are cross-sectional views showing the states before, during and after assembly of a pair of injection box pieces 1a, 1b which form the connection part of a pair of ventilation walls 5 which are assembled on site, for example.

[0043] A structure in which the ventilation wall edge 5b protruding outward from at least the end face 22 of the ventilation wall 5 is folded back in the opposite direction to the mounting direction of the adjacent jet box 1, for example, a structure in which it is folded back 180° on the top face 5a of the ventilation wall 5 in a somewhat thin edge band form as shown in the figure, is preferred. The additional protrusion or protrusion 113 formed on the folded back edge forms a protrusion disposed from the left edge to the right edge 20 of the jet box 1, so that the intrusion of oil into the jet box 1 through the gap 23 or assembly gap 23 formed on the end face between the two jet boxes to be assembled is prevented by the tongue material 19a or the protruding edge 19a.

[0044] The oil intrusion protection structure is further strengthened by providing at least one tongue member 19a or flange 19a on one of the pair of ventilation walls 5 assembled at the end face of the ventilation wall 5, and arranging the longitudinal extensions of the jet boxes 1, 1b in the assembly area of ​​the end face in the jet box 1. The tongue member 19a or flange 19a protruding toward the adjacent jet box 1a is fitted into a recess 19c formed in the end face 22 adjacent to the jet box 1a, and the tongue member 19a or flange 19a and the wall portion 5 overlap in the longitudinal direction, and a pair of continuous jet box pieces 1a, 1b are assembled. 6a, 6b and 6c respectively show the state before the adjacent jet boxes 1a and 1b are assembled, the state of the jet boxes 1a and 1b being connected in the axial direction, and the partial cross-sectional views of both ends of the jet box 1 after the jet boxes 1a and 1b are finally connected, in which the tongue or protruding edge 19a protruding from the end face 22 of one jet box 1b is engaged and fitted into the recess 19c of the end face 22 of the other adjacent jet box 1b, and the separation line 23 (FIG. 6c) between the folded ventilation wall edges 5b is disposed on the outside of the tongue 19a, and the adjacent jet boxes 1a and 1b are assembled. Due to the fitting structure in which the tongue or protruding edge 19a is engaged with the recess 19c of the end face 22 of the adjacent jet boxes 1b, the separation line between the ventilation wall edges 5b, i.e., the gap 23, is covered and sealed by the tongue 19a in the jet box 1.

[0045] This also prevents the formation of the minimum gap in the assembly area (a gap through which the oil that first separates or adheres to the top surface 5a of the injection wall 5 penetrates into the internal space 2 or the supply chamber 4). Therefore, the air supplied to the injection box 1 at the end surface can reliably prevent the transport of oil droplets from the internal space 2 through the ventilation opening 7 again toward the resin thin film.

[0046] In this way, oil adhering to the top surface 5a of the injection wall 5 is removed from the ventilation opening 7 by the annular opening edge 17, and the ventilation wall or injection wall 5 in the mounting area of ​​the end face portion is positioned to overlap with the tongue material 19a, reliably preventing oil from entering the injection box 1 even on the outside of the longitudinally opposing side surfaces of the injection box 1.

[0047] In addition to the overlapping arrangement of the tongue 19a and the injection wall 5, the additional use of a sealant introduced during assembly is also important. The sealant is arranged in the area between the upper surface of the tongue 19a and the underside of the wall 5c on the tongue 19a. In the final assembled state without the sealant, the area directly above the corresponding part of the tongue 19a becomes the wall 5c, and the wall 5 is arranged directly below the suitable folded edge 5b facing the inner space 2 of the injection box 1. If the sealant is arranged between the tongue 19a and the wall 5c, it is necessary to remove the sealant structure (e.g., by grinding it off) during disassembly and apply a new sealant during reassembly. For example, the sealant can be heat-resistant silicone, which maintains its sealing properties even at high temperatures above 150°C, or a similar or equivalent product.

[0048] However, no sealing material is usually required at all.

[0049] For example, the reinforcement and / or augmentation material 28 provided on the inside 2 of the injection box 1 below the ventilating wall or injection wall 5 shown in Figures 6a-6c is not necessarily required. For example, the reinforcement and / or augmentation material 28 can be formed in the shape of a wall, a rib, a border or all possible reinforcement shapes.

[0050] 2 is folded from the vent wall / jet wall 5 along a pair of side walls 3b and overlapping with the side wall 3b outside the side wall 3a, thereby serving the purpose of sealing to prevent oil from entering the internal space 2 of the jet box 1. In particular, each assembly part is continuous in the transverse direction Q, and is not divided into, for example, two parts, so that no gap or space between each assembly part (for example, a gap or space through which oil oozing out of the resin thin film during the stretching process enters the jet box 1) is formed in the vent wall / jet wall 5 forming the vent opening / jet opening 7.

[0051] FIG. 7a shows a partial perspective view of a number of ventilation openings 7 arranged in different geometries or configurations, for example slots, adjacent to one another along a number of rows R.

[0052] FIG. 7b shows a perspective view of a perforated plate 35 similar to the injection wall 5, which is provided with a number of slot-like air openings 7 at an inclined position relative to the longitudinal direction L of the injection box 1, for example at an acute angle of less than 45°±10° or less than 25°.

[0053] FIG. 7c shows a perspective view of an example in which a plurality of long holes are also formed in a transverse direction Q perpendicular to the longitudinal direction L of the ventilation wall of the injection box 1. FIG.

[0054] A plurality of protrusions 13 (forming at least one or more upward ventilation openings 7) are provided at intervals on the top surface 5a of the injection wall 5, a plurality of injection boxes 1 are arranged at least below the resin thin film, and the ventilation (injection) openings 7 are arranged upward relative to the lower surface of the resin thin film, so that the oil that adheres, adheres or is deposited at a position adjacent to the plurality of protrusions 13 on the upper surface or top surface 5a of the ventilation wall or injection wall 5 moves to the left or right edge (transverse direction Q of the injection box 1) of the injection box 1, and the technical idea of ​​moving the oil downward from the side edge 20 of the injection box 1 along the edge frame 21 and the side wall 3b is common to all the embodiments of the present invention. In other words, a plurality of perforated plates 35 are formed on the top surface 5a from the left edge to the right edge of the plurality of injection walls 5, so that the oil that adheres, adheres or is deposited on the upper surface or top surface 5a of the ventilation wall or injection wall 5 always flows to the side edge of the injection box 1 by bypassing the plurality of protrusions 13.

[0055] Figure 8 shows a perspective view of a plurality of jet boxes 1 spaced apart from one another in the withdrawal direction 25 of the resin film F and arranged transversely to the withdrawal direction of the resin film F below the resin film F. As shown in Figure 9, corresponding conventional jet boxes 1 are arranged at equal intervals in the withdrawal direction and at equal vertical intervals above the transport film / material strip, and also have a plurality of ventilation openings 7 arranged above the resin film F.

[0056] 9 shows a structure that utilizes multiple drains 29 (with multiple oil grooves) installed on the sides of the injection box 1. A structure in which the drains 29 are arranged at a specific angle to optimally drain the oil is preferred. Multiple grooves arranged below the drains 29 collect the oil in a capture vessel 31 and drain the oil in the capture vessel 31 through multiple drainage paths. A roof-shaped partition plate can be installed between multiple injection boxes 1 to introduce oil into the grooves and collect the oil, which has the advantage of preventing oil contamination of the heating hearth.

[0057] In particular, in a simultaneous stretching process (using a simultaneous biaxial stretching machine) of a thin plastic film in which the stretching processes in the width direction and the length direction are carried out in a heating furnace, consideration must be given to preventing oil contamination of the heating hearth. The longitudinal stretching process of the sequential stretching process is carried out in a stretching machine (which orients the thin plastic film in the machine direction) located upstream of the heating furnace. Most of the oil generated and squeezed out in the machine direction stretching process does not reach the heating furnace in the next process. Therefore, in the simultaneous stretching process or the transverse stretching process following the longitudinal stretching process, the present invention has a substantial advantage over the oil contamination problem in the heating furnace, which is expected to be more serious.

Claims

1. An injection box (1) having an internal space (2) formed by a pair of side walls (3b) spaced apart from each other, a bottom wall (3a) and a ventilation wall (5) spaced apart from the bottom wall (3a), and a plurality of ventilation openings (7) formed in the ventilation wall (5) spaced apart from each other, A plurality of protrusions (13) formed on the ventilation wall (5) with a height (H) protrude from the upper surface or top surface (5a) of the ventilation wall (5) adjacent to the protrusions (13); the plurality of vent openings (7) spaced apart in the region of the plurality of projections (13) relative to the upper or top surface (5a) of the vent wall (5) are arranged and formed farther from the interior space (2) than the upper or top surface (5a) of the vent wall (5) adjacent the projections (13); and / or A plurality of side protrusions (19a, 19b) provided on the ventilation wall (5) facing each other in the transverse direction (Q) of the injection box (1) are arranged on the outer periphery of the internal space (2) of the injection box (1) so as to overlap with a plurality of side walls (3b) of the injection box (1); The protrusion (13) of the ventilation wall (5) is formed at an embossed portion in the ventilation wall (5) having a partition and / or at a top portion which is firmly and oil-tightly connected to the ventilation wall (5); The ventilation opening (7) or at least a part of the ventilation opening (7) is formed in a circular, oblong or N-sided shape in plan view, and the protrusion (13) has a shape that corresponds to or is similar to the ventilation opening (7) located in the center of the protrusion (13) in plan view.

2. A boundary wall (15) is provided around each of the one or at least two or more ventilation openings (7); 2. The injection box according to claim 1, wherein a boundary wall (15) is formed on each of the plurality of projections (13) in a cross-sectional view at least partially at an acute angle α to the ventilation wall (5) and / or at least partially perpendicular to the inner space (2).

3. 3. The injection box according to claim 2, wherein the acute angle α of the boundary wall (15) is smaller than 90° and larger than 50°.

4. 2. The injection box according to claim 1, wherein the plurality of projections (13) are formed so as to converge in a conical shape at least in a part of the height direction away from the internal space (2).

5. 2. The injection box according to claim 1, wherein an end of the projection (13) spaced from the upper surface or top surface (5a) of the ventilation wall (5) is formed with no machining burrs and / or a rounded tip, and is formed in the form of an opening edge (17) surrounding each ventilation opening (7), and the opening edge (17) is arranged parallel to the upper surface or top surface (5a) of the ventilation wall (5) or is formed at an inclination angle of less than 45° to the parallel surface.

6. 2. The injection box according to claim 1, wherein the height of the projection (13) is 0.5 mm or more higher than the upper surface or top surface (5a) of the ventilation wall (5) or 5.0 mm or less from the upper surface or top surface (5a) of the ventilation wall (5).

7. Both side edges (20) of the ventilation wall (5) are connected to each other by a perforated plate (35), 2. The injection box according to claim 1, wherein the ventilation openings (7) are arranged or formed in one or more rows (A) in the longitudinal direction (L) of the injection box (1) at intervals in the transverse direction (Q) of the injection box.

8. 2. The injection box according to claim 1, wherein at least two vent openings (7) are arranged within one common projection (13), the vent openings (7) being surrounded by a common annular boundary wall (15).

9. The ventilation wall (5) has a ventilation wall edge (5b) extending from at least one end surface (22) of the ventilation wall (5), 2. The injection box according to claim 1, wherein the ventilation wall edge (5b) is folded or turned back from the plane of the ventilation wall (5) in a direction opposite to the longitudinal direction (L) of the injection box (1) and overlapped on the upper surface (5a) of the ventilation wall (5) and positioned at a protruding position and / or higher position than the upper surface or top surface (5a) of the ventilation wall (5) to form a band-shaped protrusion (113).

10. The injection box (1) comprises at least two injection box pieces (1; 1a, 1b) arranged in a longitudinal direction (L), A tongue or flange (24) provided in the mounting direction of at least one jet box piece (1a or 1b) in the ventilation wall (5) projects from an end face (22) of the jet box piece (1a or 1b) toward the mating jet box piece (1b or 1a) and fits into a corresponding recess (19c) of the adjacent jet box (1; 1b or 1a); 2. The injection box according to claim 1, wherein the tongue or flange (24) covers a gap (23) formed between adjacent folded air-wall edges (5b) and seals the internal space (2) of the injection box (1).

11. A drawing device comprising the injection box according to any one of claims 1 to 10.

12. The plurality of injection boxes (1) are arranged below the thin resin film (F) at intervals in the drawing direction (A) of the thin resin film (F), and 12. The stretching apparatus according to claim 11, wherein a discharge device (29) and / or a receiving device (29) are provided in the form of a catchment vessel between at least two injection boxes (1) arranged at an interval from each other in the drawing direction (A) of the resin thin film (F), and oil flowing on the upper surface or top surface (5a) of the ventilation wall (5) is collected in the discharge device (29) and / or the receiving device (29).

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