Powder and granular material static elimination device

Abstract

To easily determine the timing of maintenance by making the tip of the electrode needle visible from the outside of the casing. [Solution] This is an electrostatic eliminator (1) for powder or granular material that eliminates static electricity from powder or granular material passing through the inside of a transport pipe by ions generated at the tip (50a) of a needle electrode (50), and the glass tube (10) connected to the transport pipe has a hole (10a) formed in the tube wall, and the needle electrode (50) is housed inside a casing (21). The casing (21) also has a compressed air flow path (23) that supplies compressed air into the glass tube (10) through the hole (10a). The ions generated at the tip (50a) of the needle electrode (50) are then supplied into the glass tube (10) through the hole (10a). In this electrostatic eliminator (1), all or part of the casing (21) is made of a transparent material so that the tip (50a) of the needle electrode (50) can be seen from outside the casing (21).

Description

[Technical Field]

[0001] The present invention relates to a static eliminator for eliminating static electricity from powder or granular material such as resin pellets passing through the inside of a pipe. [Background technology]

[0002] Resin pellets are prone to static electricity due to friction, and fine powders tend to adhere to these electrostatically charged resin pellets. In particular, when resin pellets are transported by air, fine powders such as wear particles are generated, and these particles adhere to the resin pellets that have been electrostatically charged due to friction.

[0003] Since such fine powder can cause molding defects, it is preferable to remove it before feeding it into the molding machine. However, it is difficult to remove fine powder from statically charged resin pellets using only the action of airflow. For this reason, static eliminators have traditionally been used to remove static electricity from powders and granular materials such as resin pellets (see Patent Documents 1 and 2).

[0004] The static eliminators described in Patent Documents 1 and 2 each supply ions generated at the tip of an electrode needle into the inside of a pipe such as a transport pipe, and use these ions to eliminate static electricity from powdered or granular materials such as resin pellets passing through the inside of the pipe. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-133205 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-199841 Summary of the Invention [Problem to be solved by the invention]

[0006] When such static eliminators are used for a certain period of time or longer, fine powder, dirt, etc. adhere to the tip of the electrode needle, causing a decrease in static elimination performance, and therefore regular maintenance such as cleaning is required. However, the tip of the electrode needle is usually housed inside a casing, making it difficult to visually check its condition from the outside, which has created the problem of making it difficult to determine the appropriate time for maintenance.

[0007] The present invention has been made to solve such problems, and aims to provide a powder / granular material static eliminator that allows the tip of the electrode needle to be visible from outside the casing, making it easier to determine when maintenance is required. [Means for solving the problem]

[0008] The static elimination device for powder or granular material of the present invention comprises: A powder / granular material static eliminator that eliminates static electricity from powder / granular material passing through a pipe using ions generated by an ion generating unit, A hole is provided in the wall of the pipe, the ion generation unit includes a needle electrode, a casing that houses at least a tip end of the needle electrode, and a compressed gas flow path that supplies compressed gas to the inside of the tube through the hole, Ions generated at the tip of the electrode needle are supplied to the inside of the tube through the hole, The casing is characterized in that all or a part of it is made of a light-transmitting material so that at least the tip of the electrode needle is visible from outside the casing.

[0009] According to the powder / granular material de-ionization device of the present invention, all or part of the casing is made of a light-transmitting material so that at least the tip of the electrode needle is visible from outside the casing, making it easy to check the tip of the electrode needle from the outside and making it easy to determine when maintenance is required.

[0010] In the present invention, it is sufficient that at least the tip of the electrode needle is visible from outside the casing, so the "light-transmitting material" includes both transparent and translucent materials. Furthermore, as long as it transmits visible light, it does not matter whether it is colored or colorless. Specific examples of light-transmitting materials include transparent resins and transparent glass.

[0011] In one preferred embodiment of the static eliminator for powder or granular material of the present invention, the electrode needle can be attached to the casing so that the tip end thereof is positioned in the hole.

[0012] If the tip of the electrode needle is located far from the hole, ions generated at the tip may be deactivated before reaching the inside of the tube, which may reduce the static elimination effect. On the other hand, if the tip of the electrode needle protrudes too far into the tube from the hole, the powder passing through the tube may collide with the tip of the electrode needle, causing damage, etc. Therefore, it is preferable to position the electrode needle so that its tip is located in the hole, as described above.

[0013] In one preferred embodiment of the static eliminator for powder or granular material of the present invention, at least the portion of the tube including the hole is also preferably made of a light-transmitting material, which makes it easier to see the tip of the electrode needle from the outside.

[0014] In one preferred embodiment of the static eliminator for powder or granular material of the present invention, the casing is preferably made of an insulating material. If the casing is made of a good conductor, there is a risk that the effect of the ions will be hindered by the casing, but with the above-mentioned configuration, there is no such risk.

[0015] In one preferred embodiment of the powder / granular material de-ionization device of the present invention, the electrode needle is provided with a fixing portion having a plane perpendicular to its axial direction, and the plane of this fixing portion is brought into face-to-face contact with a flat portion formed on the outer wall of the casing, thereby fixing the fixing portion to the outer wall of the casing, and the electrode needle is also fixed to the casing.

[0016] With the above configuration, the tip of the electrode needle can be positioned by the surface contact between the flat part and the fixed part, making it easy to place the tip of the electrode needle at the desired location, thereby preventing problems such as the electrode needle being installed at an angle when it is installed in the casing.

[0017] Furthermore, since the fixing part is fixed to the outer wall of the casing, the electrode needle can be attached and detached by simply fixing and releasing the fixing part to the outer wall of the casing. This means that there is no need to disassemble the casing or remove the static eliminator itself from the tube to attach or detach the electrode needle, making it easy to attach and detach the electrode needle.

[0018] The "fixing portion" of the present invention does not need to be entirely flat, as long as a part of it is flat (a plane perpendicular to the axis of the electrode needle). The same applies to the "flat portion" formed on the casing side; the entire surface of the casing does not need to be flat.

[0019] In one preferred embodiment of the powder / granular material static eliminator of the present invention, The pipe has a straight pipe portion, the hole portion is formed in the pipe wall of the straight pipe portion, and an annular elastic member is tightly fixed to the outer circumferential surface of the straight pipe portion, It is preferable that the casing comprises first and second casing portions through which the straight pipe portion is inserted, and that by fastening these first and second casing portions in a direction toward each other with the annular elastic member positioned between them, the annular elastic member elastically deforms between the first and second casing portions, thereby integrating the first and second casing portions with the straight pipe portion.

[0020] With the above-described configuration, the casing can be fixed to the pipe with a simple configuration, and it is also easy to align the corresponding part on the casing with the hole on the pipe and maintain that position.

[0021] The "straight pipe section" of the present invention does not necessarily mean that the entire pipe is straight, but may mean that only a portion of the pipe is formed in a straight pipe shape. When only a portion of the pipe is formed in a straight pipe shape, the straight pipe section corresponds to the "straight pipe section" of the present invention. For example, it is the straight pipe section when a portion of a bent pipe is formed in a straight pipe shape.

[0022] Furthermore, the term "fastening" as used above includes not only fastening with bolts, but also fastening with fixing means such as screws, bands, belts, clamps, clips, etc. In short, anything that can fix the first and second casing parts close to each other along the pipe axis direction of the straight pipe part is included in the term "fastening" here.

[0023] In one preferred embodiment of the static eliminator for powder or granular material of the present invention, the number of electrode needles attached to the casing may be an even number. By configuring half of the electrode needles as positive electrodes and the other half as negative electrodes, the number of positive and negative electrodes can be made equal, making it possible to easily variably control the generation ratio of positive and negative ions and optimize the ion balance for each powder or granular material to be static eliminated.

[0024] In one preferred embodiment of the static eliminator for powder or granular material of the present invention, the static eliminator can be provided in the middle of a transport pipe for pneumatically transporting the powder or granular material, which is advantageous in that static electricity can be eliminated from the powder or granular material during pneumatic transport.

[0025] In one preferred embodiment of the static eliminator for powder or granular material of the present invention, a fine powder removal device for removing fine powder from the powder or granular material may be provided downstream of the static eliminator. This allows the powder or granular material that has been neutralized by the static eliminator in the upstream stage to be sent to the fine powder removal device in the downstream stage, thereby improving the fine powder removal efficiency of the fine powder removal device in the downstream stage.

[0026] In this specification, "granular material" refers to a powder or granular object that is transported through a pipe for subsequent use, such as processing, and that is itself the direct target of static elimination. It is distinguished from this by calling it "fine powder" which generally has a smaller particle size and is considered to be excluded from the intended use of the powder. To give an example, resin pellets fall under the category of "granular material" here, and the wear powder adhering to them and small foreign matter mixed in there fall under the category of "fine powder." [Effects of the Invention]

[0027] As described above, the present invention provides advantageous effects not available in the prior art, such as making it easier to determine when to perform maintenance on the electrode needles. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a perspective view of a static eliminator according to an embodiment; [Figure 2] FIG. 1 is an exploded perspective view of the static eliminator. [Figure 3] FIG. 10 is a side view of the static eliminator. [Figure 4] AA cross-sectional view of the static eliminator [Figure 5] Cross-sectional view of the static eliminator taken along the arrow BB [Figure 6] Cross-sectional view of the static eliminator taken along the CC arrow [Figure 7] 4 is a schematic diagram showing visibility of the vicinity of the tip of the electrode needle in the static eliminator. FIG. [Figure 8] Schematic diagram of a pneumatic conveying system for resin pellets using the static eliminator DETAILED DESCRIPTION OF THE INVENTION

[0029] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figures 1 to 7 show a static eliminator 1 according to an embodiment of the present invention.

[0030] The static eliminator 1 according to this embodiment is used to eliminate static electricity generated on resin pellets being pneumatically transported inside a transport tube. As shown in FIGS. 1 and 2, the static eliminator 1 of this embodiment includes a glass tube 10 and an ion generating unit 20.

[0031] [1] Glass tube 10 The glass tube 10 is a straight, short cylindrical tube with a circular cross section, made entirely of transparent tempered glass. While the material does not necessarily have to be tempered glass, tempered glass tubes have advantages such as abrasion resistance, visibility, and the fact that they are dielectric. A hose (not shown), which serves as the main body of the transport pipe, is connected to each end of the glass tube 10, thereby making the glass tube 10 a part of the transport pipe for supplying resin pellets. Therefore, the static eliminator 1 of this embodiment is disposed midway through the transport pipe. The diameter of the glass tube 10 is, for example, 25 mm or 38 mm.

[0032] Holes 10a are provided on the cylindrical outer peripheral surface of the glass tube 10. The glass tube 10 of this embodiment has a total of four holes 10a. Two of these holes 10a are provided at point-symmetric positions (i.e., at both ends of the diameter) on the circumference, which is the cross section when the cylindrical glass tube 10 is cut along a plane perpendicular to the tube axis direction X. On the other hand, the remaining two holes 10a are provided at positions obtained by translating the pair of holes 10a in the tube axis direction X and rotating them 90 degrees around the tube axis X, which has the above-described positional relationship. As will be described later, each of the holes 10a serves as a supply port for supplying ions and compressed air into the interior of the glass tube 10. An example of the diameter of the holes 10a is φ5 mm.

[0033] An O-ring 11 is tightly fixed to the cylindrical outer circumferential surface of the glass tube 10 (see FIGS. 2-4). As described above, when the holes 10a positioned symmetrically to each other are considered as a set, each hole 10a is divided into two sets of holes 10a spaced apart in the tube axis direction X, and the O-ring 11 is provided at the intermediate position between the two sets of holes 10a thus divided. In this embodiment, the glass tube 10 corresponds to the "straight tube portion" in the present invention, and the O-ring 11 corresponds to the "annular elastic member" in the present invention.

[0034] [2] Ion generating unit 20 The ion generating unit 20 in this embodiment includes a casing 21, an electrode unit 22, and a compressed air flow path .

[0035] [2-1] Casing 21 The casing 21 is constructed by assembling two block-shaped members 21a and 21b together. Because the block-shaped members 21a and 21b are essentially identical in shape, only one of them, the block-shaped member 21a, will be described here. (However, as will be described later, the block-shaped members 21a and 21b are positioned such that, when attached to the glass tube 10, they are rotated 90 degrees around the tube axis X.) In this section, components or parts provided on one block-shaped member 21a will be designated by a "reference numeral with an a prefix," while corresponding components or parts on the other block-shaped member 21b will be designated by a "reference numeral with a b prefix." (However, throughout the specification, a "reference numeral with an a prefix," such as "hole 10a," does not necessarily refer to a component or part provided on one block-shaped member 21a. The same applies to a "reference numeral with a b prefix.") However, for convenience of illustration, only one of the components may be shown, and the other component will also be referenced as appropriate.

[0036] The block-shaped member 21a is a solid member having a roughly rectangular parallelepiped outer shape, and is entirely made of a transparent resin material that transmits visible light. Examples of transparent resin materials that transmit visible light include acrylic resin and polycarbonate. However, the material is not limited to resin materials, and other transparent insulating materials such as glass may also be used. Note that the block-shaped member 21a in this embodiment is made of acrylic resin.

[0037] The block-shaped member 21a has a central insertion hole 31a through which the glass tube 10 can be inserted (see FIG. 2; also see "insertion hole 31b" in the same figure). The block-shaped member 21a also has a mating surface 32a that is mated with the other block-shaped member 21b (see FIGS. 2 and 3). This mating surface 32a is formed so as to be perpendicular to the tube axis direction X of the glass tube 10 when the block-shaped member 21a is attached to the glass tube 10. The opening edge of the insertion hole 31a in this mating surface 32a is chamfered into a conical shape to form an O-ring receiving portion 33a (see FIG. 4). When the block-shaped members 21a and 21b are attached to the glass tube 10 and the mating surfaces 32a and 32b are butted against each other, an O-ring 11 is sandwiched between the O-ring receiving portions 33a and 33b. In this state, when the block-shaped members 21a and 21b are further moved toward each other along the tube axis direction X of the glass tube 10, the O-ring 11 elastically deforms between the O-ring receiving portions 33a and 33b, and comes into close contact with the wall surfaces of the O-ring receiving portions 33a and 33b. As a result, as long as force is continuously applied to the block-shaped members 21a and 21b in the direction of moving them toward each other, the O-ring 11 between them restricts the relative movement between the block-shaped members 21a and 21b and the glass tube 10.

[0038] Furthermore, of the four side surfaces parallel to the axial direction of the insertion hole 31a of the block-shaped member 21a (which is also the tube axis direction X of the glass tube 10, so hereinafter there is no particular distinction between the two and both are denoted by the symbol "X"), a pair of parallel side surfaces each has a recessed portion formed on its bottom surface, which serves as a flat portion 34a (see FIG. 2). In contrast, the other pair of side surfaces does not have such a recessed portion. In this embodiment, the flat portions 34a are rectangular flat surfaces in a plan view, and the two opposing flat portions 34a are parallel to each other. The flat portions 34a further have an electrode needle receiving hole 35a and a plate fixing screw hole 36a formed therein.

[0039] The electrode needle receiving hole 35a is a through-hole (bottomless hole) in the block-shaped member 21a that communicates with the insertion hole 31a, and when the glass tube 10 is placed in the insertion hole 31a, it matches the position of the hole 10a of the glass tube 10 and communicates with the inside of the glass tube 10. In this embodiment, the axial direction of the electrode needle receiving hole 35a is perpendicular to the axial direction X of the insertion hole 31a, that is, it matches the radial direction of the insertion hole 31a.

[0040] On the other hand, the plate fixing screw hole 36a is a bottomed hole with an internal female thread. The electrode needle receiving hole 35a and the plate fixing screw hole 36a are both formed perpendicular to the flat portion 34a, and their axes are parallel to each other.

[0041] In this embodiment, one electrode needle receiving hole 35a and two plate fixing screw holes 36a are formed in each flat portion 34a, and the two plate fixing screw holes 36a are located at positions point-symmetrical to each other around the electrode needle receiving hole 35a in plan view.

[0042] Furthermore, the block-shaped member 21a is formed with a fixing bolt through-hole 37a and a fixing bolt receiving hole 38a that are formed parallel to the axial direction X of the insertion hole 31a (see FIGS. 2 and 4). The fixing bolt through-hole 37a is a hole through which a fixing bolt 39 is inserted to fasten the two block-shaped members 21a and 21b together when they are butt-joined, and is formed as a through-hole (bottomless hole) that penetrates from one side surface of the block-shaped member 21a to the other side surface parallel to the axial direction X of the insertion hole 31a. On the other hand, the fixing bolt receiving hole 38a is a bottomed hole with an internal female thread that is adapted to threadably mate with the male thread of the fixing bolt 39 that is inserted through the fixing bolt through-hole 37b of the other block-shaped member 21b.

[0043] In this embodiment, each block-shaped member 21a is provided with two fixing bolt through-holes 37a and two fixing bolt receiving holes 38a. Of these, each fixing bolt receiving hole 38a is formed in a portion between the flat portion 34a of the block-shaped member 21a and the insertion hole 31a, and at a position that is symmetrical with respect to the axis X of the insertion hole 31a. Similarly, each fixing bolt through-hole 37a is formed in a portion between the side surface of the block-shaped member 21a where the flat portion 34a is not formed and the insertion hole 31a, and at a position that is symmetrical with respect to the axis X of the insertion hole 31a. When assembling the two block-shaped members 21a and 21b, the fixing bolt through-holes 37a and 38a of one block-shaped member 21a are aligned with the fixing bolt receiving holes 38b and 37b of the other block-shaped member 21b, respectively, and then fastened together with a total of four fixing bolts 39.

[0044] Furthermore, the block-shaped member 21a is formed with a compressed air flow path 23, which will be described later.

[0045] Each of the block-shaped members 21a and 21b configured as described above is attached to the glass tube 10 by inserting each end of the glass tube 10, which has an O-ring 11 attached to its middle portion, into the corresponding insertion hole 31a or 31b. In this embodiment, the block-shaped members 21a and 21b are positioned such that, when attached to the glass tube 10, they are rotated 90 degrees relative to each other about the tube axis X. The O-ring 11 is disposed between the two block-shaped members 21a and 21b. The block-shaped members 21a and 21b are then fastened together with a fixing bolt 39 to form a single unit. The O-ring 11 elastically deforms, restricting the relative movement of the block-shaped members 21a and 21b with respect to the glass tube 10, thereby simultaneously achieving the integration of the block-shaped members 21a and 21b with the glass tube 10.

[0046] In this embodiment, one of the two block-shaped members 21a and 21b corresponds to the "first casing portion" of the present invention, and the other corresponds to the "second casing portion" of the present invention.

[0047] [2-2] Electrode section 22 The electrode unit 22 includes a needle electrode 50 and a plate 51 to which the needle electrode 50 is attached. In this embodiment, both the needle electrode 50 and the plate 51 are made of metal. The needle electrode 50 is a needle-shaped electrode with a pointed tip 50a, and the outer circumferential surface of the base end 50b is male-threaded. On the other hand, the plate 51 is a flat, plate-like member, and a female-threaded portion 51b corresponding to the male-threaded portion of the base end 50b of the needle electrode 50 is formed at its approximate center. The base end 50b of the needle electrode 50 is attached to the plate 51, thereby integrating the needle electrode 50 and the plate 51 to form the electrode unit 22. More specifically, the base end 50b of the needle electrode 50 is threadedly engaged with the female-threaded portion 51b of the plate 51, and then the plate 51 is fastened with a nut 52, thereby integrating the needle electrode 50 and the plate 51. In this embodiment, the electrode needle 50 is threadedly engaged with the plate 51, so that the electrode needle 50 can freely advance and retreat relative to the plate 51, and the position of the tip end 50a of the electrode needle 50 (specifically, the insertion depth from the outer surface of the casing 21 or the position in the radial direction of the glass tube 10) can be adjusted by adjusting how far the base end 50b of the electrode needle 50 is threaded into the female thread portion 51b of the plate 51. An example of the needle diameter of the electrode needle 50 is φ1.5 mm. In this embodiment, the plate 51 corresponds to the "fixed portion" in the present invention.

[0048] Furthermore, plate 51 is provided with fixing screw through-holes 51c at positions that are point-symmetrical with respect to female threaded portion 51b in plan view (thus, two fixing screw through-holes 51c are provided on plate 51). These fixing screw through-holes 51c correspond to plate fixing screw holes 36a and 36b on casing 21, and by inserting screws 53 into fixing screw through-holes 51c and then threading the screws 53 into plate fixing screw holes 36a and 36b on casing 21, plate 51 is fixed in a state of face-to-face contact with flat portions 34a and 34b of casing 21. In this embodiment, plate fixing screws 53 are also made of metal.

[0049] When the base end 50b of the needle electrode 50 is fixed to the plate 51 as described above and the plate 51 is further fixed to the flat portions 34a and 34b of the casing 21, the tip 50a of the needle electrode 50 is positioned at the center of the opening of the hole 10a in the glass tube 10. Meanwhile, the insertion depth of the tip 50a of the needle electrode 50 or its position in the radial direction of the glass tube 10 is such that the tip 50a of the needle electrode 50 is positioned so that it does not protrude into the interior of the glass tube 10, or protrudes slightly. In this embodiment, the plate 51 is fixed to the flat portions 34a and 34b of the casing 21 in face-to-face contact with the flat portions 34a and 34b, and at positions point-symmetrical with respect to the center of the needle electrode 50, so that the tip 50a of the needle electrode 50 can be more accurately positioned at the target location.

[0050] In this embodiment, two electrode units 22 are provided on each of the block-shaped members 21a and 21b. Therefore, a total of four electrode units 22 are provided in the static eliminator 1. Each electrode unit 22 is detachable from the block-shaped members 21a and 21b. A high-voltage cable (not shown) is connected to the electrode needles 50 of each electrode unit 22, allowing high voltage to be applied. In this embodiment, a DC voltage is applied to each electrode needle 50 so that the electrode needle 50 of one block-shaped member 21a serves as a positive electrode and the electrode needle 50 of the other block-shaped member 21b serves as a negative electrode. Therefore, the two positive electrodes are arranged opposite each other in the radial direction of the glass tube 10, and the two negative electrodes are also arranged opposite each other in the radial direction of the glass tube 10.

[0051] [2-3] Compressed air flow path 23 5 and 6, each of the block-shaped members 21a and 21b has a compressed air flow path 23. As described above, in this embodiment, the block-shaped members 21a and 21b are basically of the same shape, so here we will explain the compressed air flow path 23 provided in one of the block-shaped members, 21a.

[0052] In this embodiment, each of the block-shaped members 21a and 21b is provided with two compressed air flow paths 23 (see FIG. 5). Since each compressed air flow path 23 has the same configuration, only one of the configurations will be described here.

[0053] The compressed air flow path 23 is formed inside the block-shaped member 21a, and one end of the compressed air flow path 23 is connected to a compressed air supply connector 61, which serves as a compressed air inlet (see FIG. 6 ). In this embodiment, the compressed air flow path 23 is formed inside the block-shaped member 21a and bent in a substantially L-shape in plan view. The compressed air supply connector 61 is provided on the surface opposite the butting surface 32a of the insertion hole 31a in the axial direction X. A tube (not shown) is connected to the compressed air supply connector 61, which is further connected to a compressed air supply source (not shown). This allows compressed air to be supplied from the compressed air supply source via the tube to the compressed air supply connector 61 and then from there into the compressed air flow path 23. Meanwhile, the other end of the compressed air flow path 23 communicates with the electrode needle receiving hole 35a inside the block-shaped member 21a. This allows the compressed air supplied into the compressed air flow path 23 to be supplied through the electrode needle receiving hole 35a and into the hole 10a of the glass tube 10.

[0054] In this embodiment, compressed air is constantly supplied to the compressed air flow path 23 when a high voltage is applied to each electrode needle 50, and ions generated at the tip 50a of each electrode needle 50 are transported into the glass tube 10 by this compressed air. In this embodiment, regardless of whether the resin pellets are transported pneumatically by suction or pressure, compressed air is always supplied when ions are supplied into the glass tube 10. Therefore, the pressure and flow rate within the transport tube, or the on / off status of the transport blower that serves as the transport air source for transporting the resin pellets, are detected to determine whether or not to supply compressed air. In this embodiment, the supply pressure of the compressed air is generally constant. For example, in the case of suction transport, where the pressure within the transport tube is negative, the pressure is set to 0.2 to 0.5 MPa, and in the case of pressure transport, where the pressure within the transport tube is positive, the pressure is set to a higher pressure than the pressure within the transport tube so that the differential pressure is 0.2 to 0.5 MPa.

[0055] [3] Transparent portion in this embodiment In the static eliminator 1 of this embodiment configured as described above, the two block-shaped members 21a and 21b that occupy most of the casing 21 and the glass tube 10 are both made of transparent materials. A hole 10a is formed in the glass tube 10, and the tip 50a of the electrode needle 50 is positioned in this hole 10a. This allows the interior of the casing 21 and the state of the tip 50a of the electrode needle 50 to be easily seen from the outside (see FIGS. 4, 5, and 7. Note that in FIG. 7, the compressed air supply connector 61, the fixing bolt 39, and other components that are not directly related to the purpose of the explanation have been removed. In FIG. 7, components and parts that can be seen through the transparent members are shown with dashed lines to avoid complicating the drawing. However, this is done solely for the sake of clarity and does not represent hidden lines in the usual sense of the term used to indicate an object that cannot be seen.).

[0056] [4] Pneumatic conveying system 70 for resin pellets using this embodiment Next, an example of use of this embodiment will be described. Figure 8 is a schematic diagram of a pneumatic transport system 70 for resin pellets that uses the static eliminator 1 of this embodiment.

[0057] This pneumatic conveying system 70 is used to pneumatically convey resin pellets stored in a source tank 80 through a conveying pipe 81 and a fine powder removal filter 82 to a drying hopper 83, and the resin pellets dried in the drying hopper 83 are finally supplied to an injection molding machine 84. In this pneumatic conveying system 70, a blower 85 serving as a source of conveying air is provided upstream of the source tank 80, and one end of a conveying pipe 81 is connected to an outlet of the blower 85, and the other end of the conveying pipe 81 is connected to the fine powder removal filter 82. The source tank 80 is provided midway along this conveying pipe 81. In addition, a drying hopper 83 for drying the resin pellets is mounted above the injection molding machine 84, and the fine powder removal filter 82 is further provided above this drying hopper 83. The fine powder removal filter 82 is for removing fine powder from the resin pellets transported by the air current, and may be, for example, the fine powder removal device described in Japanese Patent No. 5695874 or a general cyclone type fine powder removal device. Note that the configuration of each device is well known, so further detailed description will be omitted.

[0058] Furthermore, in this pneumatic conveying system 70, a return pipe 86 is provided for returning the airflow from the fine powder removal filter 82 to the suction port of the blower 85, and a transport filter 87 is provided midway along this return pipe 86. As a result, the fine powder separated and removed from the resin pellets in the fine powder removal filter 82 is transported along with the airflow through the return pipe 86 to the transport filter 87, where it is separated from the airflow and collected. The airflow from which the fine powder has been removed is then sucked into the suction port of the blower 85 located downstream, and circulates again from the outlet of the blower 85 to the transport pipe 81.

[0059] The static eliminator 1 of this embodiment is provided in the middle of a transport pipe 81 between a transport source tank 80 and a fine powder removal filter 82 in the pneumatic transport system 70. Specifically, one end of a glass tube 10 of the static eliminator 1 is connected to the upstream transport pipe 81, and the other end is connected to the downstream transport pipe 81. Furthermore, each electrode needle 50 of the static eliminator 1 is connected to a high-voltage power supply 89 via a high-voltage cable 88, and each compressed air supply connector 61 of the static eliminator 1 is connected to a compressed air supply source 91 via a tube 90.

[0060] The pneumatic transport system 70 for resin pellets configured as described above operates as follows: First, the blower 85 is started to generate a circulating airflow inside the transport pipe 81 and the return pipe 86, thereby commencing the transport of the resin pellets stored in the source tank 80. Simultaneously with the generation of the circulating airflow, a high voltage is applied to each electrode needle 50 of the static eliminator 1 to generate ions at the tip end 50a, and compressed air is supplied to each compressed air flow path 23 of the static eliminator 1, which sends the ions into the interior of the glass tube 10.

[0061] The ions thus supplied to the interior of glass tube 10 neutralize the static electricity of the resin pellets passing through it. The neutralized resin pellets are then pneumatically transported to fine powder removal filter 82 further downstream, where the resin pellets are separated from the fine powder. The resin pellets from which the fine powder has been removed are then transferred to drying hopper 83 located below, where moisture is removed, and the pellets are then supplied to injection molding machine 84, their final destination.

[0062] On the other hand, the fine powder separated from the resin pellets by the fine powder removal filter 82 is carried along with the airflow through the return pipe 86 to the transport filter 87, where it is separated from the airflow and collected. Then, only the air from which the fine powder has been removed is sucked into the suction port of the blower 85 and circulates again from the outlet of the blower 85 to the transport pipe 81.

[0063] In the above-described pneumatic conveyance system 70 for resin pellets, if the static eliminator 1 is used for a certain period of time or longer, fine powder, dirt, and the like will adhere to the tip 50a of the electrode needle 50 of the static eliminator 1, causing a decrease in static elimination performance. For this reason, periodic maintenance such as cleaning will be necessary. In the static eliminator 1 of this embodiment, the two block-shaped members 21a and 21b that make up the majority of the casing 21 and the glass tube 10 are both made of transparent materials, making it easy to check the condition of the interior of the casing 21 and the tip 50a of the electrode needle 50 from the outside, and making it easy to determine when maintenance is required.

[0064] Furthermore, in the static eliminator 1 of this embodiment, each electrode portion 22 is attached to the casing 21 so that the tip portion 50a of the electrode needle 50 is positioned in the hole portion 10a of the glass tube 10. This allows the generated ions to be immediately supplied to the inside of the glass tube 10, improving the static elimination effect while preventing damage to the electrode needle 50 due to collision with the resin pellets.

[0065] Furthermore, in the static eliminator 1 of this embodiment, the glass tube 10 is also made of transparent tempered glass, which makes it easier to see the tip 50a of the electrode needle 50 from the outside, making it easier to determine when maintenance is required. Furthermore, a tempered glass tube not only has excellent visibility but also excellent abrasion resistance, and further has the advantage of not impeding the effect of ions because it is itself a dielectric.

[0066] In the static eliminator 1 of this embodiment, a plate 51 is provided at the base end 50b of the needle electrode 50, and the needle electrode 50 is fixed to the casing 21 by fixing this plate 51 to the flat portions 34a and 34b provided on the outer wall of the casing 21. Therefore, the tip end 50a of the needle electrode 50 can be positioned by the surface abutment between the plate 51 and the flat portions 34a and 34b, making it easy to place the tip end 50a of the needle electrode 50 at the desired location. This prevents problems such as the needle electrode 50 being installed at an angle when it is installed in the casing 21.

[0067] Furthermore, because plate 51 is fixed to flat portions 34a and 34b on the outer wall of casing 21, it is possible to remove needle electrode 50 by releasing it. This allows needle electrode 50 to be attached and removed without disassembling casing 21 or removing it from glass tube 10, facilitating the attachment and detachment of needle electrode 50 and allowing needle electrode 50 to be accurately returned to the correct position after cleaning.

[0068] In the static eliminator 1 of this embodiment, two block-shaped members 21a and 21b are fastened together in close proximity along the tube axis direction X of the glass tube 10, thereby elastically deforming the O-ring 11 between them. This elastically deformed O-ring 11 restricts relative movement between the two block-shaped members 21a and 21b and the glass tube 10, integrating them. This not only facilitates fixing the casing 21 to the glass tube 10, but also facilitates aligning the hole 10a of the glass tube 10 with the electrode needle receiving holes 35a and 35b of the casing 21 and maintaining that state. Since the block-shaped members 21a and 21b are transparent, visual alignment of the hole 10a with the electrode needle receiving holes 35a and 35b can be easily achieved during assembly.

[0069] In the static eliminator 1 of this embodiment, a total of four electrode needles 50 are attached to the casing 21, half of which are positive electrodes and the other half are negative electrodes, making the number of positive and negative electrodes equal. This makes it easy to variably control the generation ratio of positive and negative ions, and optimizes the ion balance for each powder or granular material to be static eliminated.

[0070] The static eliminator 1 of this embodiment is provided midway through the transport pipe 81 for pneumatically transporting resin pellets, and therefore can eliminate static electricity from the resin pellets during pneumatic transport.

[0071] In the static eliminator 1 of this embodiment, a fine powder removal filter 82 that removes fine powder is provided downstream of the static eliminator 1, which makes it easier to separate and remove fine powder from the resin pellets that have been neutralized by the static eliminator 1 in the upstream stage, thereby improving the fine powder removal efficiency of the fine powder removal filter 82 in the downstream stage.

[0072] [5] Modifications, etc. Although the present invention has been described above with reference to an embodiment, it is not limited to the embodiment. In the above embodiment, the object to be destaticized is described as resin pellets. However, the object to be destaticized is not limited to resin pellets and may be other powder or granular materials. In the above embodiment, the destaticization device is provided midway through the transport pipe. However, the location where the destaticization device is provided is not limited to the transport pipe and may be any pipe through which powder or granular material passes. One example is a discharge pipe provided at the bottom of a hopper for discharging powder or granular material stored in the hopper. Because powder or granular material passes through such a discharge pipe at the bottom of the hopper (in this case, due to gravity), the destaticization device of the present invention can be applied thereto. Furthermore, the purpose of destaticization may be other than removing fine powder as described in the above embodiment. For example, the destaticization device of the present invention may be used to reduce the static adhesion of resin pellets themselves.

[0073] In the above embodiment, a DC voltage is applied to the electrode needle, but the applied voltage is not limited to a DC voltage and may be an AC voltage. The static elimination method is not important when applying the present invention. In the above embodiment, a hole serving as a supply port for supplying ions into the tube is formed in the glass tube, but the hole may be formed in a tube other than a glass tube. Furthermore, the tube in which the hole is formed does not have to be made of a light-transmitting material.

[0074] In the above embodiment, compressed air is used as the compressed gas supplied to the static eliminator, but a gas other than air, such as an inert gas, may also be used. However, air is optimal in terms of static elimination effectiveness. Furthermore, in the above embodiment, the pressure of the compressed air supplied to the static eliminator is generally kept constant, but the pressure may be temporarily increased during cleaning or purging, or the pressure may even be varied.

[0075] In the above embodiments, all of the block-shaped members are made of a transparent material, but the entire block-shaped member does not necessarily have to be made of a transparent material. As long as the tip of the electrode needle can be seen from outside the casing, only a portion of the block-shaped member may be made of a transparent material. In the above embodiments, a transparent resin is used as the light-transmitting material that makes up the block-shaped member, but a translucent resin or a material other than resin, such as glass, may also be used. Furthermore, the block-shaped member may be either colorless or colored.

[0076] In the above embodiment, the tip of the electrode needle is positioned at the center of the opening of the hole in the glass tube, but this is not necessarily limited to this position. The positional relationship between the tip of the electrode needle and the periphery or opening edge of the hole can be set as appropriate. In the above embodiment, the tip of the electrode needle is positioned at a position where it does not protrude into the glass tube or where it protrudes slightly, but this is not necessarily limited to this position. The positional relationship in the insertion direction of the tip of the electrode needle can be set as appropriate.

[0077] In the above embodiment, the first and second casing portions are both configured as solid block-shaped members, but this configuration is not limited thereto. The first and second casing portions may be configured as hollow members by removing appropriate portions. In the above embodiment, the casing is configured as two members, the first and second casing portions, but this configuration is not necessarily required and the casing may be configured as a single member.

[0078] In the above embodiment, an O-ring is tightly fixed to the outer surface of the glass tube, and this O-ring is sandwiched between two block-shaped members to integrate the block-shaped members and the glass tube. However, the member interposed between the two block-shaped members is not limited to an O-ring, and any annular elastic member may be used.

[0079] In the above embodiment, two electrode needles are provided in each block-shaped member, and a total of four electrode needles are provided in the entire casing, but the number of electrode needles provided in each block-shaped member and the number of electrode needles in the entire casing are not limited to this configuration. The number of electrode needles may be either an even number or an odd number.

[0080] In the above embodiment, the case where the air is used in a circulation type pneumatic transport system in which the air returned to the blower through the return pipe is supplied again to the transport source tank has been described, but the air may also be used in a one-pass type pneumatic transport system in which the air used for pneumatic transport is discharged outside the system. In the above embodiment, the case where the destination of the resin pellets is a drying hopper has been described, but it does not necessarily have to be a drying hopper.

[0081] In the above embodiment, the casing of the static eliminator is exposed to the outside, but the entire casing may be further covered with a cover. In this case, the static eliminator may be entirely or partially covered with the cover. When the static eliminator is covered with a cover, the cover does not necessarily have to be made of a light-transmitting material, and may be made of an opaque material such as a metal cover. Furthermore, when the cover is made of an opaque material, the cover itself may be configured to be openable and closable, or may have a window, or may be configured to be easily attached and detached, so that the inside can be easily checked.

[0082] In the above embodiment, metal bolts, screws, etc. are used to fasten the casing body and each part, but the material of the fastening means used in the present invention is not limited to metal and may be other materials, such as insulating materials such as synthetic resins, ceramics, etc. If these are insulating materials, there is an advantage that there is no risk of the effect of ions being inhibited, unlike when they are good conductors. [Explanation of symbols]

[0083] 1...static eliminator, 10...glass tube, 10a...hole portion, 11...O-ring, 20...ion generating portion, 21...casing, 21a and 21b...block-shaped member, 22...electrode portion, 23...compressed air flow path, 31a and 31b...glass tube insertion hole, 32a and 32b...butting surface, 33a and 33b...O-ring receiving portion, 34a and 34b...flat portion, 35a and 35b...electrode needle receiving hole, 36a and 36b...plate fixing screw hole, 37a and 37b...fixing bolt through hole, 38a and 38b...fixing bolt receiving hole, 39...fixing bolt, 50...electrode needle, 50a...electrode needle tip part, 50b...base end of electrode needle (male thread part), 51...plate, 51b...female thread part, 51c...through hole for fixing screw, 52...nut, 53...screw for fixing plate, 61...compressed air supply connector, 70...air transport system for resin pellets, 80...source tank, 81...transport pipe, 82...fine powder removal filter, 83...drying hopper, 84...injection molding machine, 85...blower, 86...return pipe, 87...transport filter, 88...high voltage cable, 89...high voltage power supply, 90...tube, 91...compressed air supply source, X...axial direction of glass tube (axial direction of insertion hole)

Claims

1. A powder / granular material static eliminator that eliminates static electricity from powder / granular material passing through a pipe using ions generated by an ion generating unit, A hole is provided in the wall of the pipe, the ion generation unit includes a needle electrode, a casing that houses at least a tip end of the needle electrode, and a compressed gas flow path that supplies compressed gas to the inside of the tube through the hole, Ions generated at the tip of the electrode needle are supplied to the inside of the tube through the hole, 10. An apparatus for eliminating static electricity from powder or granular material, wherein all or a part of the casing is made of a light-transmitting material so that at least the tip of the electrode needle is visible from outside the casing.

2. 2. The static eliminator for powder or granular material according to claim 1, wherein the electrode needle is attached to the casing so that a tip end of the electrode needle is positioned in the hole.

3. 2. The static eliminator for powder or granular material according to claim 1, wherein at least a portion of said tube including said hole is also made of a light-transmitting material.

4. 2. The static eliminator for powder or granular material according to claim 1, wherein the casing is made of an insulating material.

5. 2. The powder / granular material static elimination device according to claim 1, wherein the electrode needle has a fixing portion having a flat surface perpendicular to its axial direction, and the fixing portion is fixed to the outer wall of the casing by abutting the flat surface of the fixing portion against a flat portion formed on the outer wall of the casing, thereby fixing the electrode needle to the casing.

6. The pipe has a straight pipe portion, the hole portion is formed in the pipe wall of the straight pipe portion, and an annular elastic member is tightly fixed to the outer circumferential surface of the straight pipe portion, The powder / granular material electrostatic elimination device described in claim 1, characterized in that the casing has first and second casing portions through which the straight pipe portion is inserted, and by fastening these first and second casing portions in a direction toward each other with the annular elastic member positioned between them, the annular elastic member elastically deforms between the first and second casing portions, thereby integrating the first and second casing portions and the straight pipe portion.

7. 2. The static eliminator for powder or granular material according to claim 1, wherein the number of electrode needles attached to the casing is an even number.

8. 2. The static eliminator for powder or granular material according to claim 1, wherein the pipe is a transport pipe for pneumatically transporting the powder or granular material, and the static eliminator is provided midway along the transport pipe.

9. 9. The static eliminator for powder or granular material according to claim 8, further comprising a fine powder remover for removing fine powder from the powder or granular material, disposed downstream of the static eliminator.

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