JP2010013951A - Two-shaft screw pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two-shaft screw pump capable of preventing a solid material from being crashed in transferring a transferred material including the solid material. <P>SOLUTION: This two-shaft screw pump 1 comprises: a pair of pump screws 5a and 5b having spiral teeth 21a and 21b rotated in engagement with each other without contact; a pump casing 2 formed with a pump chamber 3 which houses the pair of pump screws 5a and 5b; and a driving portion 4 supporting one end of each of the pump screws 5a and 5b so as to be turnable. The pump has an intake opening 10 on a side opposite to the driving portion 4 with the pump chamber 3 between, and takes the transferred material from the intake opening 10 into the pump chamber 3 for transference by the rotating drive of the pump screws 5a and 5b. An end surface and an outer peripheral surface of the pair of spiral teeth 21a and 21b facing the intake opening 10 are notched to form tapered surfaces 22a and 22b in the spiral teeth 21a and 21b so as to be reduced in diameter as it comes closer to the intake opening 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a twin screw pump that transfers a semi-solid or high-viscosity liquid transfer object without applying a shearing force.

Conventionally, this type of twin screw pump is shown in FIGS. A biaxial screw pump 51 shown in each figure includes a pump casing 2 in which a pump chamber 3 is formed, and a drive unit 4 connected to the pump casing 2. A base 11 having an opening 12 is bolted to the front opening of the pump casing 2. A pair of pump screws 55 a and 55 b are accommodated in the pump chamber 3. The pump screws 55a and 55b are fitted on the free ends 7 and 7 side of the shaft portions 6a and 6b, and are fixed by a mounting plate 8 and a bolt 9, respectively. The pump screws 55a and 55b include cylindrical body portions 20 and 20 through which the shaft portions 6a and 6b are inserted, and helical teeth 61a and 61b formed in a spiral shape on the outer periphery of the cylindrical body portions 20 and 20, respectively. In the pump casing 2, the front space of the free ends 7, 7 of the pump screws 5 a, 5 b serves as an intake 10 for taking the material to be transferred into the pump chamber 3. The outer peripheral surfaces 23 and 23 of the helical teeth 61 a and 61 b of the pump screws 55 a and 55 b are formed to be parallel to the inner peripheral surface of the pump chamber 3. The most distal portions of the spiral teeth 61a and 61b in the rotational direction are rotational tip surfaces 25a and 25b, respectively, along the screw radial direction. The end surfaces 24 and 24 of the helical teeth 61a and 61b facing the intake port 10 are connected to the rotary front end surfaces 25a and 25b and the outer peripheral surfaces 23 and 23, respectively.
A discharge port 19 is provided on the upper surface of the pump casing 2 at a position facing the discharge side space 18 between the pump chamber 3 and the drive unit 4. One ends of the shaft portions 6a and 6b of the pump screws 55a and 55b are rotatably supported by bearings (not shown) in the drive unit 4, and are synchronously rotated in opposite directions by synchronous gears 17a and 17b meshing with each other.

In the above-described biaxial screw pump 51, the pump screw 55a and the pump screw 55b are synchronously rotated by the rotational drive of the motor M, and the transferred object supplied from the opening 12 of the base 53 is fed from the intake port 10 to the pump screw 55a. , 55b are taken into the free ends 7, 7 side. The transferred object thus taken in is pumped through the pump chamber 3 by the pump action of the pump screws 55a and 55b, and is discharged from the discharge port 19 through the discharge side space 18. According to the biaxial screw pump 51, there is a certain fine gap between the meshing surfaces of the helical teeth 61a and 61b at any rotation angle, so that the helical teeth 61a and 61b are not in contact with each other. In other words, the biaxial screw pump 51 is suitable for transferring an object to be transported having such a high viscosity that it does not leak from the fine gap between the helical teeth 61a and 61b. It is known that it is suitable for transporting foods that are more susceptible to alteration.
A twin screw pump related to such a structure is disclosed, for example, in Patent Documents 1 and 2 below.

JP 62-276285 A JP 2005-105910 A

  Here, for example, consider a case in which a high-viscosity food containing solids is transferred by the above-described biaxial screw pump 51. In this case, as shown in FIG. 7 and FIG. 8, as shown by the inner peripheral protrusions 26 formed respectively above and below the left and right central portions in the pump chamber 3, and by the two-dot chain line arrow J in FIG. The solid substance F may be pinched and crushed between the rotating front end surface 25b (indicated by a two-dot chain line in FIG. 7) of the rotating helical tooth 61b. Such a phenomenon can also occur between the rotating tip surface 25a of the rotating helical tooth 61a and the inner peripheral protrusion 26.

Alternatively, as shown in FIG. 9 and FIG. 10, the solid F is sandwiched between the rotating front end surface 25b of the rotating helical tooth 61b and the cylindrical body portion 20 of the pump screw 55a, or is rotated or rotated. It may be crushed by being sandwiched between the rotating front end surface 25a of the pump screw 55a and the cylinder body 20 of the pump screw 55b.
When the solid matter is crushed as described above, the crushed solid pieces diffuse into the food and the texture is remarkably impaired, or a solid component having a quality different from that of the food spreads into the food. The taste may change, and in some cases it may not be useful as a product.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a twin-screw screw pump that does not crush a solid material when a material to be transported containing the solid material is transferred. .

  In order to achieve the above object, a twin-screw pump according to the present invention includes a pair of pump screws each having helical teeth that rotate in a non-contact manner and a pump chamber that houses the pair of pump screws. A pair of pump casings, and a drive unit that rotatably supports one end of the pair of pump screws, and an intake port on the opposite side of the drive unit across the pump chamber. In a biaxial screw pump that takes in a material to be transferred from the intake port into the pump chamber by the rotational drive of the screw and transfers it to the drive unit side, the end surface facing the intake port in the helical teeth of the pair of pump screws and the outer periphery connected to the end surface The pair of spiral teeth is formed with a tapered surface whose diameter is reduced toward the intake port.

  Moreover, in the said structure, the angle which the rotating shaft center of a pump screw and a taper surface comprise is set to 30 to 75 degree | times.

  According to the biaxial screw pump of the present invention, a pair of tapered surfaces whose diameter decreases toward the intake port by cutting out the end surface facing the intake port and the outer peripheral surface connected to the end surface of the helical teeth of the pair of pump screws. Therefore, the solid matter in the transferred object can escape to the gap between the tapered surface of the helical tooth and the inner peripheral wall of the pump chamber, and is guided as it is into the pump chamber. In addition, since the rotating tip surface existing at the tip in the rotational direction of the helical tooth in the prior art disappears when the tapered surface is formed, the conventional rotating tip surface and the inner peripheral protrusion of the pump chamber or the opposite pump screw It is sent to the pump chamber without being sandwiched between. Thereby, when transferring the to-be-transferred object containing a solid substance, crushing of a solid substance can be prevented.

  In addition, when the angle between the rotation axis of the pump screw and the taper surface is set to 30 degrees or more and 75 degrees or less, the solid material is reliably prevented from being crushed and the pump has a certain level of sealing performance. can do.

  The best embodiment of the present invention will be described with reference to the drawings. The embodiment described below is merely an example embodying the present invention, and does not limit the technical scope of the present invention. 1 is a side view showing a biaxial screw pump according to an embodiment of the present invention. FIG. 2 is a sectional view taken along line AA in FIG. 2, FIG. 2 is a plan sectional view of the biaxial screw pump, and FIG. 1 is a cross-sectional view taken along line B-B in FIG. However, the same components as those of the conventional biaxial screw pump 51 shown in FIGS. 6 to 10 are denoted by the same reference numerals and detailed description thereof may be omitted.

In each figure, the biaxial screw pump 1 according to this embodiment includes a front-rear cylindrical pump casing 2 in which a pump chamber 3 is formed, and a drive unit 4 connected to the rear end of the pump casing 2. ing. The pump chamber 3 is formed in a bowl shape in which the left and right central portions are constricted in the vertical and inward directions when viewed from the front. A pair of pump screws 5 a and 5 b are accommodated in the pump chamber 3. The pump screws 5a and 5b are mounted on the shaft portions 6a and 6b, and are fixed to the free ends 7 and 7 by mounting plates 8 and 8 and bolts 9 and 9, respectively. A discharge space 18 is formed between the pump chamber 3 and the drive unit 4 in the pump casing 2. A discharge port 19 for discharging the object to be transferred is formed on the upper surface of the pump casing 2 at a position facing the discharge side space 18.
In the pump casing 2, the space in front of the free ends 7, 7 of the pump screws 5 a, 5 b, that is, the space on the opposite side to the drive unit 4 across the pump chamber 3, is for taking the object to be transferred into the pump chamber 3. It is the intake 10 of.
A base 11 having an opening 12 is bolted to the front opening of the pump casing 2.

  The drive unit 4 includes a box made up of a housing 13 and a cover plate 14. A cylinder end surface of the pump casing 2 is connected to the front end surface of the cover plate 14 with a bolt or the like. A roller bearing 15 and a roller bearing 16 are provided in the housing 13. These roller bearings 15 and 16 rotatably support one end of the shaft portion 6a of the pump screw 5a. As the roller bearing 15, for example, a conical roller bearing is used. One end of the shaft portion 6b to which the pump screw 5b is attached is also rotatably supported by other roller bearings 15 and 16. A synchronous gear 17a is fixed to the shaft portion 6a of the pump screw 5a, and a synchronous gear 17b meshing with the synchronous gear 17a is fixed to the shaft portion 6b of the pump screw 5b. By the synchronous meshing of the synchronous gear 17a and the synchronous gear 17b, the pair of pump screws 5a and 5b mesh with each other in a non-contact manner and rotate. In this case, for example, the shaft portion 6a of the pump screw 5a is connected to the drive shaft of the motor M.

As shown in FIG. 4, the pump screw 5 a includes a cylindrical body portion 20 inserted through the shaft portion 6 a and helical teeth 21 a formed in a spiral shape on the outer periphery of the cylindrical body portion 20. A tapered surface 22a that is reduced in diameter toward the intake port 10 is formed at the distal end portion of the spiral tooth 21a on the intake port 10 side. In this case, the angle θ formed by the tapered surface 22a and the rotation axis Xa is set to 45 degrees, for example.
On the other hand, the pump screw 5b is configured in the same manner as the pump screw 5a except that the helical tooth 21b is formed in the direction opposite to the spiral direction of the helical tooth 21a of the pump screw 5a. These helical teeth 21a and 21b are not in contact with each other at a certain rotational angle with a certain fine gap between the meshing surfaces.
Also in this pump screw 5b, a tapered surface 22b that is reduced in diameter toward the intake port 10 is formed at the distal end portion of the spiral tooth 21b on the intake port 10 side. In this case, the angle θ formed by the tapered surface 22b and the rotation axis Xb is also set to 45 degrees, for example. Although depending on the spiral pitch of the spiral teeth 21a and 21b, in this embodiment, when the angle θ is 45 degrees, the tapered surfaces 22a and 22b are formed on the spiral teeth 21a and 21b as little as one round.

The tapered surfaces 22a and 22b of the pump screws 5a and 5b, for example, swing the point G while rotating the helical teeth 61a and 61b (see FIG. 6 and others) of the pump screw 55a in the prior art around the rotation axes Xa and Xb. The end face that faces the intake port 10 at the helical teeth 61a and 61b by applying a cutting blade that is a moving center or a cutting blade that moves along a 45-degree line passing through the point G (both of which are not shown). 24 and the outer peripheral surface 23 in the vicinity of the intake 10 connected to the end surface 24 can be cut out. Thereby, the rotation front end surfaces 25a and 25b possessed by the helical teeth 61a and 61b are also excised.
In addition, if the material of each above-mentioned component is used for a screw pump, it will not specifically limit. In the case of this configuration, since the object to be transferred is food with high viscosity, at least the pump casing 2, the pump screws 5a and 5b, the shaft portions 6a and 6b, the mounting plate 8, the bolt 9, the base 11, and the cover plate 14 are Consists of stainless steel.

  The operation of the twin-screw pump 1 having the above-described configuration will be described with reference to FIGS. When the pump screw 5a rotates in one direction (in the direction of arrow Ra in FIG. 3) due to the rotational drive of the motor M, the pump screw 5b transmitted through the synchronous gears 13a and 13b rotates in the reverse direction (in the direction of arrow Rb in FIG. 3). ) Synchronously rotate. Therefore, when the transferred object is supplied from the opening 12 of the base 11 to the intake port 10 in the pump casing 2, the transferred object is taken into the pump chamber 3 from the intake port 10 by the pumping action of the pump screws 5a and 5b. It is.

  In this case, the outer peripheral surfaces of the helical teeth 21 a and 21 b in the vicinity of the intake port 10 are tapered surfaces 22 a and 22 b that decrease in diameter toward the intake port 10. In addition, the spiral teeth 21a and 21b do not have the rotating front end surfaces 25a and 25b (see FIG. 7 and others). Accordingly, the solid matter F contained in the transferred material escapes into the gap between the tapered surfaces 22a and 22b of the spiral teeth 21a and 21b and the inner peripheral wall of the pump chamber 3. It is guided to the pump chamber 3 as it is. Moreover, it is not pinched | interposed between the conventional rotation front end surfaces 25a and 25b, and the inner wall of the pump chamber 3, the internal peripheral protrusion 26, or the opposite cylinder trunk | drum 20, and is sent in the pump chamber 3 without trouble. . Thereby, the to-be-transferred object containing the solid substance F can be sent, without the solid substance F being crushed. As described above, the transferred object taken into the pump chamber 3 and transferred (in the direction of arrow E in FIG. 2) reaches the discharge side space 18 in the pump casing 2 and is discharged from the discharge port 19.

  In the above-described embodiment, an example in which one end side of the shaft portion of the pump screw is supported by a bearing and the other end side is not supported as a free end is shown, but the present invention is not limited thereto. For example, the present invention can also be applied to a double-sided bearing type pump in which both ends of a pump screw shaft are rotatably supported.

  In the above description, the angle θ formed by the rotation axis of the pump screw and the tapered surface is set to 45 degrees, but the present invention is not particularly limited thereto. However, it is preferable to set the angle formed by the rotation axis of the pump screw and the tapered surface to 30 degrees or more and 75 degrees or less. Depending on the helical pitch of the helical teeth, if the angle of the tapered surface is less than 30 degrees, it becomes easy to prevent crushing of solids, but a tapered surface will be formed over the circumference of the helical tooth, There is a problem that the sealing performance with the peripheral surface is lowered, the transfer pressure is lowered, and the pump efficiency is easily lowered. On the other hand, when the angle exceeds 75 degrees, the sealing performance of the pump is improved, but it becomes difficult to guide the solid material into the pump chamber due to the tapered surface, and the solid material cannot be completely crushed.

  Moreover, as a to-be-transferred object containing the solid substance suitably transferred with the biaxial screw pump of this invention, the molten chocolate containing a bean etc. are mentioned, for example.

It is a side view which shows the biaxial screw pump which concerns on one Embodiment of this invention, and is AA arrow sectional drawing in FIG. It is a plane sectional view of the 2 axis screw pump. FIG. 3 is a cross-sectional view taken along line B-B in FIG. 2. It is a top view of one pump screw. It is the schematic perspective view which looked up at FIG. 3 diagonally. It is a top view including the partial cross section of the conventional biaxial screw pump. It is CC sectional view taken on the line in FIG. It is the schematic perspective view which looked down at FIG. 7 diagonally. It is another state explanatory drawing corresponding to FIG. It is the schematic perspective view which looked down at FIG. 9 diagonally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 2 screw pump 2 Pump casing 3 Pump chamber 4 Drive part 5a, 5b Pump screw 6a, 6b Shaft part 10 Inlet 21a, 21b Spiral tooth 22a, 22b Tapered surface 23 Outer peripheral surface 24 End surface F Solid substance Xa, Xb Rotating shaft Center θ angle

Claims (2)

A pair of pump screws each having helical teeth that rotate in mesh with each other, a pump casing in which a pump chamber for housing the pair of pump screws is formed, and one ends of the pair of pump screws are rotatable. And a drive unit to be supported, and an intake port on the opposite side of the drive unit across the pump chamber. By rotationally driving the pair of pump screws, an object to be transferred is taken into the pump chamber from the intake port. In the twin screw pump that transfers to the drive side,
An end face facing the intake port of the spiral teeth of the pair of pump screws and an outer peripheral surface connected to the end surface are cut out, and a tapered surface whose diameter decreases toward the intake port is formed in the pair of spiral teeth. Twin screw pump. The biaxial screw pump according to claim 1, wherein an angle formed between the rotation axis of the pump screw and the tapered surface is set to 30 degrees or more and 75 degrees or less.

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