Screw pump

Abstract

To provide a screw pump capable of releasing fitting between a screw and a rotational shaft, even when a large force must be applied to remove the screw from the rotational shaft due to poor assembly or a state of fitting between a screw fitting shaft part and a shaft fitting hole.SOLUTION: Screw fitting shaft parts 22 of rotary shafts 2a, 2b are provided with a tapered shaft part 22a with a truncated conical shape, whose diameter gradually decreases toward a free end, while shaft fitting holes 33 of screws 3a, 3b are provided with a tapered hole part 33a with the same taper angle as the tapered shaft parts 22a. The screw fitting shaft parts 22 and the shaft fitting hole parts 33 are fitted so that an outer peripheral surface of the tapered shaft part 22a and an inner peripheral surface of the tapered hole part 33a are in close contact with each other. Therefore, it is possible to always make the screws 3a, 3b into a misalignment-free state and screw a draw bolt 5 into a female screw part 34 provided on the screws 3a, 3b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a screw pump. [Background technology]

[0002] Twin-shaft screw pumps are used as pumps for transporting fluid food ingredients and cosmetics, and the applicant of the present invention has already put on the market, for example, a twin-shaft screw pump X shown in FIG. 8 (Non-Patent Document 1). As shown in FIG. 8, this twin-shaft screw pump X generally includes two rotary shafts 100a and 100b that are driven to rotate by a motor (not shown), and two screws (rotors) 200a and 200b.

[0003] The two screws 200a, 200b are housed in a casing 300 with the screw blades 210 and screw grooves 220 having opposite spiral directions relative to the other, and the screw blades 210 of one screw 200a (200b) meshing with the screw grooves 220 of the other screw 200b (200a). The two screws 200a, 200b are fitted with screw fitting shaft portions 110 provided on the rotating shafts 100a, 100b into shaft fitting holes 230 drilled in the screws 200a, 200b, and with the screws 200a, 200b positioned around their axes using a key not shown, a retaining bolt (fixing bolt) 400 is threaded from the open end side of the screws 200a, 200b into a female threaded hole 130 for the retaining bolt provided at the tip of the rotating shafts 100a, 100b, thereby preventing the rotating shafts 100a, 100b from coming loose, and allowing the screws to rotate within the casing 300 as the rotating shafts 100a, 100b rotate. In some screw pumps, the screw fitting shaft portion has a tapered shaft portion in the shape of a truncated cone that gradually reduces in diameter, and the shaft fitting hole portion of the screw is provided with a tapered hole portion that reduces in diameter at the same taper angle as the tapered shaft portion and fits into the tapered shaft portion. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] https: / / www.fukko.com / products / screw / Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the configuration having a tapered shaft portion and a tapered hole as described above, if the axial length of the tapered shaft portion and the axial length of the tapered hole are increased, the fit becomes too strong and the screw cannot be easily removed. Therefore, specialized tools are required for removal, and disassembly takes a great deal of time, which poses a problem in that the cost of disassembly is too high for applications requiring frequent disassembly and cleaning.

[0006] In view of the above circumstances, the present invention aims to provide a screw pump that can easily release the engagement between the screw and the rotating shaft, even when the engagement between the rotating shaft and the screw is strong and a large force must be applied to remove the screw from the rotating shaft. [Means for solving the problem]

[0007] In order to achieve the above object, the screw pump of the present invention comprises a casing, at least one rotating shaft which is journaled within the casing at one end and has a screw-fitting shaft portion at the other end, the screw having an internally threaded hole for a retaining bolt at the tip thereof, a through hole which has a shaft-fitting hole portion at at least one end which fits into the screw-fitting shaft portion, and which is rotatable within the casing as the rotating shaft rotates with the screw-fitting shaft portion fitted into the shaft-fitting hole portion, and the screw fits the screw-fitting shaft portion into the shaft-fitting hole portion and the retaining bolt is threaded into the internally threaded hole for the retaining bolt by the head of the retaining bolt, and the through hole has an internally threaded portion into which the extractor bolt can be threaded when the extractor bolt is removed and the tip of the extractor bolt is abutting against the tip of the screw-fitting shaft portion.

[0008] The screw pump of the present invention is not particularly limited, but is suitable for a multi-shaft screw pump having two or more rotating shafts, the screws being attached to these rotating shafts in the aforementioned retained state, and in the aforementioned retained state, adjacent screws are in a state in which the screw blades of one screw are inserted into the screw groove of the other screw. That is, as described above, when the screw blades of one screw are inserted into the screw groove of the other adjacent screw, it is necessary to pull out both screws while keeping them roughly parallel to each other so as not to damage the screws. However, although it is difficult to apply the right amount of force when pulling out screws by hand, by gradually rotating each extraction bolt in a balanced manner, it is possible to easily pull out both screws while keeping them roughly parallel to each other. [Effects of the Invention]

[0009] As described above, the screw pump of the present invention comprises a casing, at least one rotating shaft which is journaled within the casing at one end and has a screw-fitting shaft portion at the other end, the screw having an internally threaded hole for a retaining bolt at the tip thereof, a through hole which has a shaft-fitting hole portion at at least one end thereof that fits into the screw-fitting shaft portion, and which is rotatable within the casing as the rotating shaft rotates with the screw-fitting shaft portion fitted into the shaft-fitting hole portion, and the screw fits the screw-fitting shaft portion into the shaft-fitting hole portion and the retaining bolt is threaded into the internally threaded hole for the retaining bolt so that the screw is prevented from coming out of the screw-fitting shaft by the head of the retaining bolt, and the through hole has an internally threaded portion into which the extractor bolt can be threaded when the extractor bolt is removed and the tip of the extractor bolt is abutting against the tip of the screw-fitting shaft portion, thereby providing the following advantageous effects.

[0010] That is, after the retaining bolt is removed from the screw fitting shaft portion, when the extraction bolt is tightened into the female thread portion, the tip of the extraction bolt is first received by the tip of the screw fitting shaft portion. Furthermore, when tightening the screw using a tool such as a wrench, the reaction force from the rotation shaft acting on the extraction bolt causes the screw to slide in the extraction direction, making it easy to remove. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a partially cutaway side cross-sectional view showing one embodiment of a screw pump of the present invention. [Figure 2] FIG. 2 is a plan cross-sectional view of the screw pump of FIG. 1. [Figure 3] FIG. 2 is a side view of the screw of the screw pump of FIG. 1. [Figure 4] 2 is a partially cutaway cross-sectional side view of the screw pump of FIG. 1 with a discharge port forming member removed. FIG. [Figure 5]2 is a partially cutaway side cross-sectional view illustrating the start of an operation to screw a draw bolt into the screw of the screw pump of FIG. 1. FIG. [Figure 6] 6 is a side cross-sectional view, partly cut away, illustrating a state in which a draw bolt is screwed into the screw in FIG. 5 and the screw is being drawn out. FIG. [Figure 7] FIG. 2 is a diagram illustrating a state in which the screw is removed from the rotary shaft of the screw pump in FIG. 1. [Figure 8] FIG. 1 is a plan sectional view of a conventional screw pump. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below with reference to the drawings showing embodiments thereof. 1 and 2 show a twin-screw pump which is one embodiment of the screw pump of the present invention.

[0013] As shown in Figures 1 and 2, this twin-shaft screw pump A comprises a casing 1, a first rotating shaft 2a, a second rotating shaft 2b, a first screw 3a, and a second screw 3b, each of which is made of stainless steel. The casing 1 includes a shaft support portion 11 for the first rotating shaft 2a and the second rotating shaft 2b, a material supply portion 13, a screw accommodating portion 12, and a discharge portion .

[0014] The first rotating shaft 2a and the second rotating shaft 2b are arranged in parallel, and one end of each is supported by the shaft support portion 11 so as to be rotatable around a central axis, and the second rotating shaft 2b rotates in the opposite direction to the first rotating shaft 2a, following the rotation of the first rotating shaft 2a. The other ends of the first rotary shaft 2a and the second rotary shaft 2b form a screw-fitting shaft portion 22 that faces the inside of the screw accommodating portion 12. Furthermore, the first rotating shaft 2a has a drive transmission section 21, one end of which protrudes outside the casing 1, and the rotational driving force of a drive motor (not shown) is transmitted to this drive transmission section 21, causing it to rotate and also transmitting the driving force to the second rotating shaft 2b within the shaft support section 11.

[0015] The screw fitting shaft portion 22 is adapted to fit into the shaft fitting holes 33 of the first screw 3a and the second screw 3b described later, and includes a tapered shaft portion 22a, a first cylindrical shaft portion 22b, and a second cylindrical shaft portion 22c.

[0016] The first cylindrical shaft portion 22b extends from the small diameter end of the tapered shaft portion 22a toward the discharge portion 14 while maintaining the same diameter as the small diameter end. The second cylindrical shaft portion 22c extends from the end of the first cylindrical shaft portion 22b toward the discharge portion 14 side in a state in which the diameter of the second cylindrical shaft portion 22c is reduced in a stepwise manner compared to the first cylindrical shaft portion 22b. The second cylindrical shaft portion 22c has a female threaded hole 22d for a retaining bolt drilled at its tip into which a retaining bolt 4 (described later) is threadedly engaged.

[0017] As shown in Figure 2, the first screw 3a and the second screw 3b are fixed to the first rotating shaft 2a or the second rotating shaft 2b so that the screw blades 31 of the first screw 3a and the screw blades 31 of the second screw 3b have an inverse spiral shape and the screw blades 31 of the first screw 3a (second screw 3b) are inserted into the screw grooves 32 of the second screw 3b (first screw 3a). As shown in FIG. 3, the first screw 3a and the second screw 3b each have a through hole 30, one end of which is provided with a shaft fitting hole portion 33, and the other end of which is provided with a female thread portion 34.

[0018] The shaft fitting hole portion 33 has a tapered hole portion 33a in the direction of the shaft support portion 11, which has a taper angle that is the same as the taper angle of the tapered shaft portion 22a of the screw fitting shaft portion 22, and is continuous with this tapered hole portion 33a and has, toward the discharge portion 14 side, a first cylindrical hole portion 33b having an inner diameter slightly larger than the outer diameter of the first cylindrical shaft portion 22b, and a second cylindrical hole portion 33c having an inner diameter slightly larger than the outer diameter of the second cylindrical shaft portion 22c. The female thread portion 34 also serves as a bolt insertion hole, and is provided at the end opposite the shaft fitting hole portion 33 of the first screw 3a and the second screw 3b so as to communicate with the second cylindrical hole portion 33c.

[0019] The first screw 3a and the second screw 3b have their shaft fitting holes fitted into the screw fitting shaft portion 22 of the first rotating shaft 2a or the second rotating shaft 2b, respectively, so that the inner surface of the tapered hole portion 33a and the outer surface of the tapered shaft portion 22a are in close contact with each other, and then the screw retaining bolt 4 is threaded into the female threaded hole 22d for the retaining bolt, thereby fixing the screws to the first rotating shaft 2a or the second rotating shaft 2b. The discharge portion 14 has a flange portion 14a fixed to the end face of the screw accommodating portion 12 via a bolt 14b, and can be removed from the screw accommodating portion 12 by removing the bolt 14b.

[0020] This twin-screw pump A is configured as described above, and the screws can be removed and installed as follows.

[0021] [Screw removal] (1) Loosen the bolt 14b and remove the discharge part 14 as shown in FIG. (2) Although only the second screw 3b is shown in FIG. 4, after removing the screw retaining bolts 4 of the first screw 3a and the second screw 3b, as shown in FIG. 5, a removal bolt 5 is threaded into the female thread portions 34 of the first screw 3a and the second screw 3b, and the tip of the removal bolt 5 is abutted against the tip surface of the second cylindrical shaft portion 22c. (3) Using a tool such as a wrench, two draw bolts 5 are gradually screwed alternately into the female thread portions 34 of the first screw 3a and the second screw 3b, or the two draw bolts 5 are screwed in simultaneously, so as not to apply a large force that would cause distortion between the screw blades 31 of the first screw 3a and the second screw 3b. The reaction force from the first rotating shaft 2a and the second rotating shaft 2b shifts the first screw 3a and the second screw 3b toward the tips of the first rotating shaft 2a and the second rotating shaft 2b so that a gap S is formed between the tapered shaft portion 22a and the tapered hole portion 33a, as shown in Figure 6. (4) Once the gap S is formed, pull out the first screw 3a and the second screw 3b together with the draw bolt 5, and then remove the draw bolt 5 from the first screw 3a and the second screw 3b as shown in FIG. 7.

[0022] [Screw installation] (1) As shown in FIG. 2, the first screw 3a and the second screw 3b are pushed into the screw accommodating section 12 with their screw blades 31 and screw grooves 32 engaged with each other, and with their respective fitting hole portions 33 facing the corresponding screw fitting shaft portion 22 of the first rotating shaft 2a as shown in FIGS. 2 and 4, until the tapered hole portion 33a is completely fitted into the tapered shaft portion 22a. (2) The threaded portions of the screw retaining bolts 4 are screwed into the first rotating shaft 2a and the second rotating shaft 2b to fix the first screw 3a and the second screw 3b. (3) As shown in FIGS. 1 and 2, the discharge portion 14 is attached to the screw receiving portion 12.

[0023] As described above, in the twin-shaft screw pump A, the first rotating shaft 2a and the second rotating shaft 2b have tapered shaft portions 22a on the screw engaging shaft portions 22, and the shaft engaging hole portions 33 of the first screw 3a and the second screw 3b have tapered hole portions 33a having the same taper angle as the tapered shaft portions 22a. Therefore, the first screw 3a and the second screw 3b can be fixedly supported to the first rotating shaft 2a and the second rotating shaft without any skill or difficulty and without misalignment. In particular, since the tapered shaft portion 22a is provided at the base end of the screw fitting shaft portion 22, one end of the first screw 3a and the second screw 3b is firmly positioned, and the other end is fixed by the screw retaining bolt 4, thereby further reducing misalignment.

[0024] Furthermore, in the twin-shaft screw pump A, the through holes 30 of the first screw 3a and the second screw 3b are provided with female thread portions 34. Therefore, even if the shaft fitting hole portion 33 and the tapered shaft portion 22a are tightly fitted together, the first screw 3a and the second screw 3b can be easily removed from the first rotating shaft 2a and the second rotating shaft 2b by screwing the removal bolt 5 into the female thread portions 34 using a tool such as a wrench. Moreover, by alternately and gradually screwing in the two draw bolts 5 or simultaneously screwing in the two draw bolts 5 so as not to apply a large force that would cause distortion between the screw blades 31 of the first screw 3a and the second screw 3b, the first screw 3a and the second screw 3b can be removed from the first rotating shaft 2a and the second rotating shaft 2b without damaging the first screw 3a and the second screw 3b or the first rotating shaft 2a and the second rotating shaft 2b. It can be extracted.

[0025] The present invention is not limited to the above-described embodiment. For example, although the above-described embodiment is directed to a two-shaft screw pump, the pump may be a single-shaft or three or more-shaft pump. In the above embodiment, there is one pair of tapered shaft portion and tapered hole portion, but two or more pairs may be provided.

[0026] In the above embodiment, all parts are made of stainless steel, but the materials constituting each part can be selected appropriately depending on the application of the pump. Not only metallic materials but also composite materials can be used. For example, only the parts that come into contact with the transported material can be made of stainless steel. In the above embodiment, as shown in the figure, the number of spiral turns of the screw blade is three, but the number of spiral turns and pitch of the screw blade can be determined appropriately depending on the application of the pump. [Explanation of symbols]

[0027] A Twin Screw Pump 1 casing 11 Shaft support part 12 Screw receiving section 13 Material supply section 14 Discharge part 14a Flange 14b Bolt 2a First rotation axis 2b Second rotation axis 21 Drive transmission unit 22 Screw fitting shaft 22a Tapered shaft 22b First cylindrical shaft 22c Second cylindrical shaft 22d Fixing bolt screw hole 3a First screw 3b Second screw 30 through holes 31 screw blade 32 screw grooves 33 Shaft fitting hole 33a Tapered hole 33b 1st cylindrical hole 33c 2nd cylindrical hole 34 Female thread 4 Screw retaining bolt 5 Extraction bolt

Claims

1. A casing; At least one rotating shaft, one end of which is supported within the casing, the other end of which has a screw-fitting shaft portion, and the tip of the screw-fitting shaft portion has a female threaded hole for a retaining bolt; a screw having a through hole, the through hole having a shaft fitting hole portion at at least one end thereof that fits into the screw fitting shaft portion, the screw being rotatable in the casing in association with the rotation of the rotary shaft with the screw fitting shaft portion fitted into the shaft fitting hole portion; In the screw pump, the screw is prevented from coming off the screw fitting shaft portion by the head of the retaining bolt when the screw fitting shaft portion is fitted into the shaft fitting hole portion and the retaining bolt is screwed into the retaining bolt female threaded hole, a screw pump characterized in that the through hole has an internal thread portion on its inner surface into which the extraction bolt can be screwed when the anti-pullout bolt is removed and the tip of the extraction bolt is in contact with the tip of the screw engagement shaft portion.

2. The rotary shaft has two or more. The screws are attached to these rotary shafts in the aforementioned retaining state, and 2. The screw pump according to claim 1, wherein, in the retained state, the screw blades of adjacent screws are inserted into the screw grooves of the other screw.

Images