WO2016052265A1

WO2016052265A1 - Centrifuge and swing rotor for centrifuge

Info

Publication number: WO2016052265A1
Application number: PCT/JP2015/076709
Authority: WO
Inventors: 佐藤　淳; 建一根本
Original assignee: 日立工機株式会社
Priority date: 2014-09-30
Filing date: 2015-09-18
Publication date: 2016-04-07
Also published as: DE112015004494B4; CN106573255B; CN106573255A; JPWO2016052265A1; JP6195023B2; DE112015004494T5

Abstract

A centrifuge having a plurality of buckets (40) that are provided in a swingable manner by being latched to the holding pins of a swing rotor body in order to ensure sufficient width of contact between the convex parts of the holding pins and the concave parts of the buckets and to optimize the size of a chamfer or roundness provided to the convex parts of the holding pins, wherein the holding pins are convex parts protruding from the swing rotor body and have a cylindrical surface on the outer periphery, the buckets have concave parts corresponding to the convex parts, and the concave parts include an arcuate pin-receiving part (44) that presses against the convex parts of the holding pins during swinging, and an orthogonal surface (45) that faces the axially distal surface of the convex parts, a continuous groove part (46) being formed in a reverse U-shape in side view on the outside of the orthogonal surface (45). The groove part (46) has a hemispherical groove cross-section, and the axis of the holding pin passes above the orgthogonal surface. Forming the groove part (46) makes it possible to disperse the localized stress concentrated on corner sections, etc., and to increase the service life of the bucket (40).

Description

Centrifuge and swing rotor for centrifuge

The present invention relates to a swing rotor type centrifuge (centrifuge) used for separating a sample in the fields of medicine, pharmacy, genetic engineering, biotechnology, etc., and in particular, a bucket holding function that is held and swings by a swing rotor. It is about improvement.

The centrifuge includes a rotor capable of accommodating a plurality of sample containers filled with a sample therein, and a motor (driving means) that rotationally drives the rotor in the rotor chamber, and acts on centrifugal force by rotating the rotor in the rotor chamber. By doing so, the sample in the sample container is centrifuged. Centrifuge rotors can be broadly classified into angle rotors and swing rotors. In the case of an angle rotor, a plurality of sample containers filled with a sample are accommodated in the accommodation hole, and a lid for reducing windage loss is fastened to the rotor above the accommodation hole opening. The receiving hole is formed at a fixed angle with respect to the drive shaft, and the relative angle between the receiving hole and the drive shaft is always fixed regardless of the magnitude of the centrifugal force.

On the other hand, the swing rotor rotates a bucket that has a bottomed portion and accommodates a sample container that is filled with a sample so as to be swingable with respect to the swing rotor body. The centrifugal load applied to the bucket is held by a pair of holding pins (convex portions) installed on the opposing surfaces of the arms of the swing rotor body. A recess is formed on the two side surfaces of the bucket so as to engage with the cylindrical surface on the outer peripheral side of the holding pin of the swing rotor body, and the recess is mounted so as to hang downward from the holding pin. Is slidably held by. A clearance is provided between the front end surface of the holding pin and the opposing surface (orthogonal surface) of the concave portion of the bucket so as not to prevent sliding. When the swing rotor is stationary without rotating, the vertical axis of the bucket and the drive shaft of the motor are parallel (swing angle θ = 0 °), but can swing as the rotor speed increases. Centrifugal force acts on the bucket installed on the swing shaft, the bucket rotates about the swing axis and θ> 0 °, and is substantially horizontal (swing angle θ≈90 at a rotational speed that generates centrifugal force to add the bucket horizontally) °). After that, the centrifugal angle is finished, and the swing angle θ decreases as the rotational speed of the rotor decreases, and θ = 0 when stopped. Thus, the swing rotor changes the relative angle between the central axis of the bucket and the drive shaft according to the magnitude of centrifugal force during centrifugation.

In such a swing rotor, since the centrifugal load applied to the bucket is borne by the contact surface at the end of the recess provided on the side surface of the bucket, various attempts have been made to reduce the stress applied partially. For example, in Patent Document 1, at the recess end provided on the side of the bucket that is slidably engaged with a pair of protrusions formed on the rotor, the stress concentration position is provided at the corner of the recess in order to reduce stress concentration due to load. It has been proposed to further provide a partially spherical recess as roundness greater than roundness.

Japanese Patent Laid-Open No. 62-114670

The rotor has a pair of opposing convex portions that support the bucket so as to be swingable, and is provided with a concave portion on the side surface of the bucket that engages with the outer peripheral side cylindrical surface of the convex portion, and the concave portion is provided with the reinforcing portion Is slid and engaged with the convex portion of the rotor, and swings at the end of the concave portion. The bucket swings around the central axis of the convex cylindrical surface. The size of the contact surface between the bucket and the convex cylindrical surface of the rotor is determined by the outer diameter of the convex cylinder, the contact width determined by the convex cylindrical surface and the concave end surface of the bucket, and the roundness provided on the ridgeline at the convex tip. It is determined by the size of the chamfer. The load of the bucket, the sample, and the sample container is borne by the contact surface of the bucket, and the stress concentrates on the roundness or the arc-shaped portion provided at the corner of the recess. In recent years, there is a desire to process a large amount of sample at a time or to process at a higher centrifugal acceleration, but when the bucket size is increased according to the request, the conventional swing rotor structure has The resulting stress is high (stress concentration). Since this stress concentration significantly affects the repeated life of the bucket, the roundness or arc shape of the recess corner is usually set as large as possible in order to relieve the stress. However, if the roundness or arc shape of the corner of the recess is increased, it will interfere with the roundness or chamfering of the tip ridge line of the convex portion of the rotor, which will affect the swing. The possibility of damaging the roundness or arc shape of the part increases. In order to avoid this damage, normally, when the roundness or arc shape of the concave portion of the bucket is made large, the rounding or chamfering of the leading edge of the convex portion of the rotor is provided so as not to interfere. However, increasing roundness or chamfering now requires reducing the contact width. The reduction of the contact width means that the contact surface pressure, that is, the contact stress, increases, causes cracks on the contact surface and surface roughness, which deteriorates slidability and promotes breakage from the contact surface. It opens up possibilities.

In addition, the rotor front end surface and the opposite surface (relative surface) of the bucket concave portion are attached by sliding and engaging with the convex portion by the reinforcing portion provided in the bucket concave portion. Since it is necessary to be able to swing, it is necessary to provide an appropriate gap. Furthermore, the amount of unbalance with respect to the center of rotation is such that the center plane position parallel to the rotation center axis between the pair of convex portions facing the rotor and the plane parallel to the rotation center axis that passes through the center of gravity of the bucket, sample, and sample container coincide. Since the vibration is reduced and the vibration during rotation becomes low, it is desirable that the gap is small. However, if the roundness or the substantially arc-shaped shape of the concave portion of the bucket is increased so as not to interfere with the roundness or chamfering of the convex edge of the convex portion of the rotor, the roundness of the bucket concave portion facing the convex tip surface comes into contact with the roundness. Therefore, there is a problem that the gap between the front end surface of the convex portion of the rotor and the relative surface of the bucket concave portion becomes large.

The present invention has been made in view of the above background, and an object of the present invention is to provide a centrifuge and a swing rotor for a centrifuge that can suppress a decrease in the life of the bucket due to stress concentration on the corners of the recesses of the bucket. Another object of the present invention is a centrifugal system that optimizes the size of roundness and chamfering provided on the ridge line at the tip of the convex portion of the holding pin while ensuring a sufficient contact width of the swing surface between the bucket and the convex portion of the holding pin. And a swing rotor for a centrifugal machine. Still another object of the present invention is to reduce the amount of unbalance caused by the size of the gap between the convex portion of the holding pin and the bucket and to enable stable centrifugation without giving unnecessary vibration to the sample. The object is to provide a centrifuge and a swing rotor for the centrifuge.

The characteristics of representative ones of the inventions disclosed in the present application will be described as follows. According to one aspect of the present invention, the drive shaft rotated by the drive means, the swing rotor main body mounted on the drive shaft, the plurality of holding pins arranged on the swing rotor main body, and the holding pin are latched. Therefore, in a centrifuge having a plurality of buckets arranged so as to be swingable, the holding pin is a convex portion formed on the swing rotor body and has a cylindrical surface on the outer periphery, and the bucket has a concave portion corresponding to the convex portion. . The concave portion of the bucket has a parallel region facing the outer peripheral surface of the holding pin and a vertical region facing the front end surface of the convex portion, and the vertical region is a groove formed continuously along the boundary with the guide surface. A flat portion is formed in a groove portion whose depth direction is the axial direction of the holding pin and a portion surrounded by the groove portion. In the parallel region, a pin receiving portion that is a semi-cylindrical surface corresponding to the outer peripheral shape of the holding pin and a guide surface formed by two opposing flat surfaces are formed. The groove portion has an inverted U shape when viewed from the axial direction of the holding pin, and the cross-sectional shape thereof is curved, particularly preferably hemispherical, and the width of the groove in the cross section passing through the axis of the holding pin is a convex portion. Less than half the diameter.

According to another feature of the invention, the guide surface extends substantially parallel downward from the semi-cylindrical surface and is formed by a side surface of a rib for guiding attachment to the convex portion of the bucket. Further, the groove portion is continuously formed from the pin receiving portion so as to be in contact with substantially the entire guide surface. The interval W1 between the guide surfaces in the direction orthogonal to the bucket mounting direction on the guide surface is configured such that W1> 2G with respect to the width G of the groove.

According to the present invention, it is possible to reduce the roundness or chamfering of the ridgeline at the tip of the convex portion of the rotor to ensure the contact area between the convex portion and the concave portion, and to set the clearance between the convex portion tip and the relative surface of the bucket concave portion to be small. It has become possible. In addition, it was possible to reduce the stress of buckets that were in a high stress state due to stress concentration in the past, and to realize a centrifuge with less abnormal vibration. Further, the gap between the rotor convex portion tip surface and the bucket concave portion relative surface is set to an arbitrary gap regardless of the rounded or chamfered size provided on the ridge line at the rotor convex tip, and is caused by the size of the gap. The amount of unbalance is reduced, and it is possible to prevent unnecessary vibrations from being applied to the sample.

It is a front view of the centrifuge by this invention, and has shown the principal part with sectional drawing. It is a section perspective view of rotor assembly 2 of centrifuge 1 concerning the example of the present invention. It is a bottom view of the rotor main body 20 and the bucket 40 of the centrifuge 1 which concerns on the Example of this invention. It is a perspective view of the bucket 40 of FIG. FIG. 4 is a side view of the centrifuge 1 according to the embodiment of the present invention during high-speed rotation of the rotor, and is a view of the inner peripheral side from the AA portion of FIG. 3. FIG. 6 is a cross-sectional view taken along a line BB in FIG. 5 and shows a state where the rotor body 20 is rotating. It is a side view of the bucket 40 single-piece | unit of the centrifuge 1 which concerns on the Example of this invention. It is a fragmentary perspective view for demonstrating the shape of the pin receiving part 44 vicinity of the bucket 40 of FIG. It is the elements on larger scale of the contact part of a bucket and a rotor main body, Comprising: (1) is a shape which concerns on the Example of this invention, (2) is a shape in the conventional centrifuge. It is a longitudinal cross-sectional view which shows the contact state of a bucket and a rotor main body, Comprising: (1) is a shape which concerns on the Example of this invention, (2) is a shape in the conventional centrifuge. It is a perspective view which shows the bucket 140 manufactured with the pin receiving structure of the prior art. It is the side view in high speed rotation of the bucket 140 of FIG. 11, Comprising: It is the figure which looked at the inner side from the outer peripheral side.

Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same portions are denoted by the same reference numerals, and repeated description is omitted. Further, in this specification, description will be made assuming that the front, rear, left, right, top, bottom, inner peripheral side, and outer peripheral side are directions shown in the drawing. Moreover, the case where it is substantially the same as the said numerical value shall be included. In addition, when referring to the positional relationship, for example, when referring to parallel, orthogonal, plane, opposite, etc., not only when it is completely parallel, orthogonal, plane, opposite, but also substantially parallel, substantially orthogonal, The case where it is substantially opposite is included.

FIG. 1 is a longitudinal sectional view of a centrifuge 1 of the present invention. The centrifuge 1 includes a box-shaped housing 11 and is partitioned into two upper and lower spaces by a partition plate 12 near the upper and lower centers inside the housing 11. The upper space of the partition plate 12 accommodates a substantially cylindrical chamber 4 whose upper surface is open, and a protective wall 6 is disposed on the outer peripheral side of the chamber 4. The upper surface of the chamber 4 is sealed by an openable / closable door 14, thereby forming the rotor chamber 3. A refrigeration pipe 16 is wound around the chamber 4 and the interior of the rotor chamber 3 is maintained at a desired temperature by a cooling device (not shown). A rotor assembly 2 is installed in the rotor chamber 3. The rotor assembly 2 is a set of a swing rotor and a housing cover 30 that houses the swing rotor. In this embodiment, the swing rotor rotates while being housed in the housing cover 30. The swing rotor includes a rotor main body 20 attached to the drive shaft 7a and a plurality of buckets 40 that are held swingably with respect to the rotor main body 20. In a conventional swing rotor type centrifuge, the swing rotor is rotated without using the storage cover 30. However, in the present invention, the centrifugal operation may be performed without using the storage cover 30. It is not essential for the invention.

A motor 7 as a drive source is accommodated in the housing 8 at the lower stage partitioned by the partition plate 12 in the housing 11, and the housing 8 is fixed to a mounting member 13 to the partition plate 12 via a damper rubber 9. The The motor 7 is arranged such that its drive shaft 7a extends in the vertical direction. The drive shaft 7a extends from a through hole formed in the bottom portion of the chamber 4 so as to reach the internal space of the rotor chamber 3, and a crown 7b for transmitting the rotational torque of the drive shaft 7a is provided at the upper end portion thereof. The rotor assembly 2 is held by the crown 7b. As the rotor assembly 2 rotates at a high speed, the bucket 40 swings around the swing axis by centrifugal force. The rotor assembly 2 can be detached from the rotor chamber 3 in the state of the assembly in this way, and the lid 33 of the housing cover 30 is removed while the rotor assembly 2 is set in the centrifuge 1. It is also possible to remove the bucket 40.

An operation display unit 10 is provided on the inclined panel 15 on the upper rear side of the housing 11. The operation display unit 10 functions as an input unit for receiving input from the user and a display unit for displaying information to the user, and can be formed by a plurality of buttons and an LED display device. You may comprise using a liquid crystal display. Although not shown in FIG. 1, display of information on the operation display unit 10 and control of receiving operation input from the user, rotation control of the motor 7, control of a cooling device (not shown) for flowing the refrigerant through the refrigeration pipe 16 A control unit (not shown) for controlling the entire centrifuge 1 is provided. The control unit is an electronic circuit that includes a microcomputer, volatile and nonvolatile storage memories, and the like.

FIG. 2 is a cross-sectional perspective view of the rotor assembly 2 of the centrifuge 1 according to the embodiment of the present invention. The rotor assembly 2 includes a rotor body 20 in which a plurality of buckets 40 are set inside a housing cover 30 including a shell 31, a base 32, and a lid 33 (the rotor body 20 also includes a coupling 36 attached with screws). It is a housed assembly. FIG. 2 shows a state in which the sample container 50 in which the sample 55 is placed inside the bucket 40 is mounted. The bucket 40 has an inner wall shape that matches the outer shape of the sample container 50, and is manufactured by integral molding of an aluminum alloy. The housing cover 30 is used to prevent a temperature rise due to frictional heat with the air due to the unevenness of the rotor assembly 2 and to reduce noise such as wind noise during rotation of the rotor assembly 2 in the centrifugal separation operation. It is important that the thermal conductivity is good, the strength is excellent, and the weight is light. Here, it is made of a metal such as an aluminum alloy. The shell 31 is provided with a lower opening annular base 32, and the shell 31 and the base 32 form a bowl-shaped container. The base 32 is provided with a circular through hole in the center, and a coupling 36 for fixing the rotor body 20 is attached to the upper part of the through hole.

A circular opening 31 a larger than the outer diameter of the rotor body 20 is formed on the upper side of the shell 31. A disc-shaped lid 33 is attached to the opening 31 a of the shell 31. A knob 34 is attached to the center of the lid 33, and a through hole is provided in the center of the knob 34. The upper end of the lock screw 35 can be inserted into the through hole, and the opening 31a of the shell 31 can be closed. Therefore, the lid 33 is only on the top of the shell 31. The base 32 and the coupling 36 of the shell 31 are fixed by screws, the housing cover 30 and the rotor body 20 can move together, and a fitting hole 36 a provided in the coupling 36 is set in the crown 7 b of the centrifuge 1. After that, the rotor assembly 2 is fixed to the centrifuge 1 by screwing the screw portion 35a of the lock screw 35, which is rotatably attached to the rotor body 20, into the screw portion 36b provided on the crown 7b.

Next, the detailed structure of the swing rotor (the rotor body 20 and the bucket 40) will be described with reference to FIG. FIG. 3 is a bottom view of the rotor body 20 and the bucket 40 of the centrifuge 1 according to the embodiment of the present invention (here, the coupling 36 is not shown). A holding pin 26 protruding in a convex shape from the rotor body 20 is hooked in a concave depression (concave portion) formed in the bucket 40. The rotor body 20 includes a hub 21 having a substantially rectangular parallelepiped outer diameter in which a through hole 22 is formed, an arm portion 23 that extends radially outwardly from the hub 21 and extends in a cross shape when viewed from above, and an arm portion 23. A branch arm portion 24 connected so as to spread in a V shape from the vicinity of each tip, and a rib 25 for improving strength by connecting adjacent branch arm portions 24 with a planar member. . The rotor body 20 is manufactured mainly by precision casting made of stainless cast steel or aluminum alloy, and only a portion requiring combination accuracy is cut by machining. The hub 21 is a place to be installed on the coupling 36. When the number of buckets 40 to be attached is four, the four arm portions 23 are arranged around the rotation axis (rotation center) of the hub 21 at intervals of 90 °. Evenly arranged. Depending on the number of attached buckets 40, the number of arm portions 23 and the interval (rotation angle) between the arm portions 23 can be arbitrarily set, but the rotation target with respect to the through hole 22 (concentric with the rotation axis) It is preferable to set so that

On the outer portion of the arm portion 23, there are formed a branch arm portion 24 that branches into two at an angle of about 90 degrees, and a rib 25 that joins the branch arm portions 24 with a plate-like member. The The branch arm portion 24 extends in a direction perpendicular to the rotation axis, and is in a positional relationship parallel to the branch arm portion 24 opposed to the bucket 40 therebetween. One bucket 40 is held by these parallel branch arm portions 24. Each branch arm portion 24 has a substantially cylindrical shape for supporting the bucket 40, and is formed with a holding pin 26 protruding so as to be a convex portion with respect to the bucket 40 side. The direction in which the holding pin 26 extends (the axial direction of the holding pin 26) is the same direction as the tangential direction of the rotation locus of the rotor body 20.

Before describing the bucket 40 of the present embodiment, the shape of the holding pin and the shape of the bucket of the swing rotor manufactured using the conventional technique will be described with reference to FIGS. 11 and 12. FIG. 11 is a perspective view showing a bucket 140 formed by a conventional technique, particularly a conventional pin receiving structure. The bucket 140 is manufactured by integral molding of a metal such as an aluminum alloy, for example, and has a cup shape having a substantially rectangular opening 141 when viewed from above. In the vicinity of the upper end, which is in the vicinity of the opening 141, a thick portion 142 having a partially increased thickness is formed, and a recess 145 sandwiched by two guide ribs 143 is formed downward from the thick portion 142. . A pin receiving portion 144 having an arcuate outer peripheral surface is formed on the upper end of the recess 145 and below the thick portion 142 as a contact surface when the bucket 140 swings. The inner wall of the arc-shaped pin receiving portion 144 is preferably a semi-cylindrical shape slightly larger than the outer diameter of the holding pin 26 (FIG. 2). In FIG. 11, only the guide rib 143 and the pin receiving portion 144 connected to one thick portion 142 can be seen, but the same guide rib 143 and pin receiving portion 144 are also formed on the thick portion 142 located on the opposite side. The

The guide rib 143 serves as a guide for guiding the holding pin when the bucket 140 is mounted on and removed from the rotor main body. A guide surface 143a, which is a wall surface formed on the recess 145 side of the guide rib 143, is formed so as to face the outer peripheral side sliding surface (cylindrical shape) of the holding pin, and is in the axial direction of the swing axis. It becomes a plane area (plane area) formed in parallel. In FIG. 11, only the guide ribs 143 connected to one side of the thick portion 142 and the recesses (dents 145, pin receiving portions 144, guide surfaces 143a) formed in a portion surrounded by the ribs and formed in a concave shape in a side view. Although not visible, a similar concave portion is formed in the thick portion 142 located on the opposite side, and a recess 145 and a pin receiving portion 144 are formed at two locations on the long side of the bucket 140.

FIG. 12 is a side view of the conventional centrifuge during high-speed rotation of the rotor, as seen from the outer peripheral side toward the inner side. It can be understood from this figure that the centrifugal load is held by the bucket 140 being pivotally supported by the holding pin 126 formed on the branch arm portion 124 of the swing rotor. A boundary portion between the recess 145 and the guide surface 143a of the guide rib 143 is not a right angle at the corner of the recess 145 serving as a recess of the bucket 140, and the corner 145c is formed to be slightly rounded. A similar roundness is also formed at the boundary between the depression 145 and the pin receiving portion 144, which are vertical planes. This is because the roundness of the corner 145c must be smaller than the roundness (chamfering) of the corner 126c at the tip of the holding pin 126. In order to reduce the stress concentration by increasing the roundness of the corner of the concave recess 145, the roundness of the corner 126c of the holding pin 126 must be further increased. Therefore, the cylindrical surface 126b and the pin receiving portion 144 In addition to the decrease in the contact area, the gap between the recess 145 and the front end surface 126a of the holding pin 126 is increased. When the contact area decreases, the contact surface pressure, that is, contact stress increases, causing cracks in the contact surface and surface roughness of the contact surface, resulting in poor slidability and a cause of poor swinging of the bucket 140. End up. Further, if the clearance between the front end surfaces 126a of the holding pins 126 is large, the amount of movement of the bucket 40 in the axial direction of the holding pins increases, so that there is a high possibility that unbalance will occur during rotation. The present invention has been made in order to solve these problems.

FIG. 4 is a perspective view of the bucket 40 used in the centrifuge 1 according to the present embodiment. The bucket 40 is detachable with respect to the rotor main body 20, and can be mounted on the rotor main body 20 by moving the bucket 40 from top to bottom (mounting direction: downward parallel to the axial direction). The bucket 40 has an opening 41 at the top, and an internal space 48 for accommodating a plurality of sample containers 50 is formed below the opening 41. In the present embodiment, the bucket 40 in which the opening 41 is in an open state is illustrated, but an openable / closable lid may be formed in the opening 41. The bucket 40 is manufactured by integral molding of a metal such as an aluminum alloy, for example, and has a cup shape having a substantially rectangular opening 41 when viewed from above, and the periphery of the opening 41 is partially A thick part 42 having an increased thickness is formed. The bucket 40 of the present embodiment has a shape in which the internal space 48 is separated into two.

On the long side surface of the bucket 40, a thick portion 42 and a concave portion sandwiched by two guide ribs 43 extending downward from the thick portion 42 are formed. This concave portion is concave when viewed from the axially outer side of the swing axis of the bucket, and the width of the concave portion is slightly larger than the diameter of the holding pin 26 so that the holding pin 26 can be guided. It is. The main purpose of the guide rib 43 is to form the guide surface 43 a for guiding the holding pin 26, but the rigidity of the bucket 40 can be significantly increased by forming the guide rib 43. In the present embodiment, a continuous groove portion 46 facing the tip end side of the cylindrical surface of the pin receiving portion 44 and having an inverted U shape in a side view in a region orthogonal to the swing axis (the bottom portion in terms of the recess). Formed. The inner surface of the inverted U-shaped groove 46 is formed with an orthogonal surface 45 that is a flat surface orthogonal to the swing axis.

FIG. 5 is a side view of the centrifuge 1 according to the embodiment of the present invention when the rotor of the centrifuge 1 is rotating at a high speed, and is a side view as seen from the AA portion of FIG. The difference between the conventional centrifuge and the centrifuge 1 according to the present embodiment is mainly the shape of the bucket 40, and the shape of the corner of the holding pin 26 is optimized according to the bucket 40. The holding pin 26 has a substantially cylindrical shape, and its axis (swing axis) is the swing center of the bucket 40. The portion of the holding pin 26 that contacts the bucket 40 is a cylindrical surface 26 b, and the tip end surface 26 a is formed at the tip end in the axial direction of the holding pin 26 in a direction perpendicular to the swing axis. On the other hand, on the bucket 40 side, a pin receiving portion 44 having a cylindrical inner wall shape is formed, and the pin receiving portion 44 comes into contact with the cylindrical surface 26b. On the bucket 40 side, an orthogonal surface 45 is formed in a vertical region facing the front end surface 26a. In this embodiment, a groove 46 is formed on the radially outer side of the orthogonal surface, and the locally concentrated stress of the bucket 40 is formed. Was configured to be dispersed. The groove 46 can be formed by cutting using an end mill having a hemispherical cutting tip shape. The groove contour of the groove 46 is semicircular when viewed from the bottom view (or the cross-sectional view of FIG. 6) as shown in FIG. 5, but the reason for providing the groove is to disperse the stress concentrated locally at the corners and the like. Therefore, other cross-sectional shapes may be used as long as the cross-sectional shape is not only a perfect semicircular shape but also a curved shape. The tip surface 26a and the orthogonal surface 45 are configured to face each other with a slight gap. This gap is such that the bucket 40 can be smoothly attached to the rotor body 20 and the bucket 40 can swing smoothly when the rotor body 20 rotates, and should be formed as small as possible.

Next, the cross-sectional shape of the BB portion in FIG. 5 will be described with reference to FIG. This section is because the rotor main body 20 is rotating at high speed and the bucket 40 is swinging horizontally, so that the section of the BB section is the center axis (swing axis) of the holding pin 26 and the center axis of the bucket 40. It will be a surface that passes through. The bucket 40 is swingably supported while sliding along the pin receiving portion 44 of the holding pin 26, and the centrifugal load of the bucket 40 is supported by the pin receiving portion 44 coming into contact with the cylindrical surface 26 b of the holding pin 26. In the portion of the bucket 40 adjacent to these contact surfaces, a groove 46 is formed on the contact surface (cylindrical half surface) on the axial center side of the swing axis. Here, the orthogonal surface 45 of the bucket 40 with respect to the holding pin 26 is necessarily faced on the swing axis of the holding pin 26. This is necessary to provide a gap between the front end surface 26 a of the holding pin 26 and the orthogonal surface 45 of the bucket 40. The width of the groove 46 is determined by the radius of the hemispherical cross-sectional shape, but there is no problem even if the tip surface 26a of the holding pin 26 and the orthogonal surface 45 of the bucket 40 are reduced to the extent that they remain parallel ridgelines. Here, the width of the groove 46 is reduced to about 2/3 of the radius of the holding pin 26 so that the groove 46 is not positioned on the central axis (swing axis) of the holding pin 26. As a result, when viewed from the swing axis of the holding pin 26, the tip surface 26 a and the orthogonal surface 45 are close enough to face each other with a small gap, so that there is little shaking when the bucket 40 is swung, and the rotation center of the rotor body 20 is not affected. The amount of unbalance is reduced, and vibration during rotation can be kept low. The bucket 40 is provided with a bucket partition plate 41b for dividing the internal space into two.

FIG. 7 is a side view of a single bucket 40 of the centrifuge 1 according to the embodiment of the present invention. What is drawn with a dotted line is the position of the holding pin 26 during the centrifugal separation operation. A guide rib 43 serving as a reinforcing portion is provided on a side surface of the bucket 40, and a concave portion is formed using the thick portion 42 and the guide rib 43. The concave portion is a region which becomes a bottom portion of the groove and is a vertical region which is a side facing the front end surface of the holding pin 26 and a parallel region which is formed orthogonal to the vertical region. The vertical region is a region extending in the vertical direction on the distal end side of the holding pin 26 when viewed from the axial direction of the swing axis. On the other hand, the parallel region is a region formed by a plane parallel to the swing axis, and is a surface that cannot be seen in the side view of FIG. The groove 46 and the orthogonal surface 45 formed in the vertical region can be visually recognized in a side view.

In the manufacturing method of the concave portion of the bucket 40, first, the portion between the two parallel guide ribs 43 is buried and is manufactured to have a continuous and identical surface, and then the concave portion is formed by cutting. . To form the recess, first, an end mill (not shown) having the same diameter as the width G of the groove 46 is positioned parallel to the swing axis and brought close to 46c of the bucket 40, moved in the direction of the arrow 49a, and reversed near the upper end. And move to the arrow 49b while moving in an inverted U shape. As a result, a deep groove is formed only in the groove portion 46, and a guide surface 43a and a cylindrical pin receiving portion 44 are formed. Next, an end mill (not shown) having a diameter greater than or equal to W and having a flat tip cutting surface is positioned at the lower end of the island portion formed by the formation of the groove portion 46, and from below as indicated by an arrow 49c. The orthogonal plane 45 is formed by moving to the vicinity of the center of the swing axis while cutting upward. As a result of such cutting, a recess is formed in a portion sandwiched between the guide ribs 43. Here, it can be understood that the guide surface 43a of the guide rib 43 and the pin receiving portion 44 are adjacent to each other so that the surfaces thereof are continuous, and the boundary portion between the guide surface 43a and the groove portion 46 is also continuously formed. Will.

The position of the holding pin 26 at the time of rotation of the rotor body 20 is a range indicated by a dotted line in FIG. 7, and a range D from the top is a relative portion facing the holding pin 26. A portion below the relative portion is an extension portion formed to guide the bucket 40 when the bucket 40 is attached to the holding pin 26. In the present embodiment, when the groove 46 is basically formed only in the relative portion having the length D in the vertical direction, the locally concentrated stress of the bucket 40 can be dispersed during the centrifugal separation operation. However, if the groove portion 46 is cut only at the relative portion, the end of the groove portion is located near the transition portion from the groove portion 46 to the extension portion, and there is a possibility that stress is concentrated not a little. Is sufficiently long to extend from the top to the bottom. If it forms in this way, it will also become possible to form each part of a recessed part efficiently by cutting, and the raise of a cutting cost can be suppressed significantly.

A recess for guiding the holding pin 26 is formed inside the guide rib 43 formed in parallel as described above. In this embodiment, the interval W1 between the guide surfaces 43a of the guide ribs 43 in the extension region viewed in the direction orthogonal to the mounting direction of the bucket 40 is constant from top to bottom, that is, the guide surfaces 43a are formed in parallel. Considering the role as a guide for guiding the holding pin 26 when mounting and removing the rotor 40 on the rotor main body, the guide rib 43 has a width W1 (= W + 2G) on the upper side and slightly wider on the lower side. May be formed slightly obliquely.

Next, the shape of the concave portion of the bucket 40 will be further described with reference to FIG. FIG. 8 is a partial perspective view for explaining the shape of the recess formed on the side surface of the bucket 40. The concave portion is divided into a parallel region mainly serving as a wall surface and a vertical region serving as a bottom surface portion. In FIG. 8 (1), the blackened portion shows a wall surface that becomes a parallel region, and the upper side of this wall surface is a pin receiving portion 44 that contacts the holding pin 26 when the bucket 40 swings. A guide surface 43a, which is a flat surface extending from the columnar surface to the extended portion, is provided below.

The portion blacked out in FIG. 8B is the shape of the groove 46 as viewed from the side. The reverse outer peripheral portion 46a of the groove portion 46 is in a position in contact with the upper surface of the pin receiving portion 44, and the reverse inner peripheral portion 46b of the groove portion 46 is above the axis (center point) of the swing shaft. That is, the swing axis is configured to be located in the orthogonal plane 45 that is a plane. For this reason, since the orthogonal surface 45 and the front end surface 26a of the holding pin 26 can face each other in a substantially parallel state on the swing axis, a swing mechanism with less backlash can be realized. In addition, since the periphery of the facing surface is a groove portion 46, it is easy to bring the orthogonal surface 45 and the front end surface 26a close to each other, and the swinging operation is smooth and the risk of the bucket 40 being displaced is greatly increased. Can be reduced.

The portion filled in black in FIG. 8 (3) is a side view of the orthogonal plane 45. When the orthogonal surface 45 is attached to the bucket 40, the axial position of the bucket 40 is determined by contacting the tip of the holding pin 26 in the axial direction. Since it has a sufficient length of more than half of the vertical distance, the bucket 40 mounting mechanism that can properly position the holding pins 20 of the bucket in the axial direction can be realized.

Next, the cross-sectional shape of the holding pin 26 and the cross-sectional shape of the groove 46 will be described with reference to FIGS. 9 and 10. (1) is the shape of the concave portion of the bucket 40 of this embodiment, and (2) is the shape of the concave portion of the bucket 140 using the conventional technique. FIG. 9 is a transverse sectional view (horizontal sectional view) passing through the axis of the holding pin 26. In (1), the bucket 40 vertical region is a portion that is all disposed within the range of the width 51 and indicated by the arrow 52, and the orthogonal surface 45 and the groove 46 are formed in this portion. The pin receiving portion 44 is a semi-cylindrical surface formed in a parallel region, and is in good contact with the cylindrical surface 26 b of the holding pin 26. Here, because of the relationship in which the groove portion 46 is formed, the radius of curvature of the corner portion 26c between the cylindrical surface 26b and the tip surface 26a of the holding pin 26 can be made sufficiently small. If the shape of the holding pin 26 is optimized in accordance with the bucket 40 thus improved, the axial width L1 of the contact portion between the cylindrical surface 26b and the pin receiving portion 44 can be secured large. Further, the groove portion 46 is formed so as to be within the range 51 and the range of the arrow 52, and is formed so as not to protrude to the parallel region side where the pin receiving portion 44 is present. As a result, since the curved surface portion by the groove portion 46 does not interfere with the contact portion between the pin receiving portion 44 and the cylindrical surface 26b, the swing characteristics of the bucket 40 can be kept good. This advantage is clear when the structure of the bucket 140 according to the prior art shown in (2) is compared. In the bucket 140, the curvature radius of the corner 126c of the holding pin 126 is not increased due to the relationship with the curvature radius of the corner 145c. Therefore, the axial width L2 of the contact portion between the cylindrical surface 126b and the pin receiving portion 144 becomes small. This increases the stress due to the centrifugal load applied to the cylindrical surface 126b of the holding pin 126, and also increases the local stress received by the pin receiving portion 144 on the bucket 140 side.

Further, as described with reference to FIG. 8, the orthogonal surface 45 can be formed at an arbitrary height (arbitrary depth when viewed as a concave portion) in order to cut after the processing of the groove portion 46 is finished. Can be appropriately set so as to face each other at a minute interval, and a bucket 40 without backlash can be realized. Here, the gap S <b> 2 between the deepest part of the groove in the groove 46 and the tip surface 26 a of the holding pin 26 is configured to be sufficiently larger than the gap S <b> 1 with the orthogonal surface 45. According to the conventional technique shown in (2), it is necessary to secure the gap S3 to some extent because of the possibility of interference between the corner 145c and the corner 126c. Further, when the bucket 140 is shifted in the axial direction of the holding pin and the orthogonal surface 145a and the front end surface 126a come into contact with each other, there is a possibility that the smooth swing of the bucket 40 may be hindered because the contact area is large. However, in the configuration of the present embodiment of (1), even if the orthogonal surface 45 and the tip surface 26a come into contact with each other, the contact area is small, so that a smooth swing can be realized. In the present embodiment, it is important that the orthogonal surface 45 and the tip surface 26a face each other in a non-contact manner or in contact with each other on the swing axis, and it is not preferable to configure the groove 46 on the swing axis.

FIG. 10 is a vertical cross-sectional view (vertical cross-sectional view) passing through the axis of the holding pin 26. In (1), the concave portion of the bucket 40 is formed such that the groove portion 46 is formed within the range of the width 53 on the upper side from the holding pin line, and the orthogonal surface 45 is formed on the lower side of the groove portion 46. Here, the groove 46 is formed so as not to exceed the range 53 when viewed in the vertical direction. The lower side of the range 53 is the position of the swing axis, and the upper side is the upper end position of the inner wall of the pin receiving portion 44. As described above, the groove portion 46 is formed at the bottom portion of the concave portion of the bucket 140 and is formed along the boundary between the bottom portion and the wall portion, so that it does not affect the surface on the pin receiving portion 44 side. Formed.

As described above, according to the present embodiment, the pair of opposed convex holding pins 26 that support the bucket so as to be swingable are arranged on the opposite sides, and the bucket engages with the cylindrical surface 26 b of the holding pin 26. Since the concave portion is provided on the side surface, the concave portion is formed by the groove portion 46 having a rounder or substantially arc shape larger than the corner portion 26c provided on the tip edge line of the holding pin 26 of the rotor and the orthogonal surface 45 inside the groove portion 46. Further, it is possible to prevent the life of the bucket 40 from being shortened due to partial stress concentration at the corner of the concave portion of the bucket 40. In addition, since the contact width L1 between the cylindrical surface 26b of the holding pin 26 and the bucket 40 can be increased, it is possible to prevent cracking of the contact surface and surface roughness of the contact surface due to increased contact surface pressure, that is, contact stress. Furthermore, since an appropriate gap is provided in the orthogonal surface 45 of the front end surface 26a of the holding pin 26 and the concave portion of the bucket 40, the amount of unbalance caused by the size of the gap can be reduced, and the bucket 40 can be made smooth. A centrifuge that does not give unnecessary vibration to the sample can be realized.

As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to the above-mentioned Example, A various change is possible within the range which does not deviate from the meaning. For example, in the present embodiment, the bucket 140 has been described as having a shape in which the opening 41 is substantially rectangular. However, the shape of the bucket is not limited to this, and the shape of the opening is a substantially circular cylindrical bucket. It may be a bucket of any other shape.

DESCRIPTION OF SYMBOLS 1 ... Centrifuge, 2 ... Rotor assembly, 3 ... Rotor chamber, 4 ... Chamber, 6 ... Protective wall, 7 ... Motor, 7a ... Drive shaft, 7b ... Crown, 8 ... Housing, 9 ... Damper rubber, 10 ... Operation Display part 11 ... Housing, 12 ... Partition plate, 13 ... Mounting member, 14 ... Door, 15 ... Inclined panel, 16 ... Refrigeration pipe, 20 ... Rotor body, 21 ... Hub, 22 ... Through hole, 23 ... Arm part 24 ... Branch arm portion, 25 ... Rib, 26 ... Holding pin, 26a ... End face, 26b ... Cylindrical surface, 26c ... Corner, 30 ... Housing cover, 31 ... Shell, 31a ... Opening, 32 ... Base, 33 ... Lid, 34 ... Knob, 35 ... Lock screw, 35a ... Screw part, 36 ... Coupling, 36b ... Screw hole, 40 ... Bucket, 41 ... Opening part, 41b ... Bucket partition plate, 42 ... Thick part, 43 ... Guide rib, 43a ... Guide , 44 ... Pin receiving part, 45 ... Orthogonal surface, 46 ... Groove part, 46a ... Inverted outer peripheral part, 46b ... Inverted inner peripheral part, 48 ... Internal space, 50 ... Sample container, 55 ... Sample, 120 ... Rotor body, 124 ... branch arm part, 126 ... holding pin, 126a ... tip surface, 126b ... cylindrical surface, 126c ... corner part, 140 ... bucket, 141 ... opening part, 142 ... thick part, 143 ... guide rib, 143a ... guide surface, 144: Pin receiving portion, 145a ... Orthogonal surface, 145b ... Guide surface, 145c ... Corner

Claims

A drive shaft rotated by the drive means, a swing rotor body mounted on the drive shaft, a plurality of holding pins arranged on the swing rotor body, and swingable by being hooked on the holding pins. In the centrifuge having a plurality of buckets, the holding pin is a convex portion formed on the swing rotor body and has a cylindrical surface on the outer periphery, and the bucket has a concave portion corresponding to the convex portion, The concave portion of the bucket is formed with a surface facing the tip surface of the convex portion, a pin receiving portion, and a guide surface formed by two opposing flat surfaces, and the opposing surface has a boundary with the guide surface The centrifuge is characterized in that a groove portion that is continuously formed along the groove and in which the depth direction of the groove is the axial direction of the holding pin, and a flat portion is formed in a portion surrounded by the groove portion.
The groove portion has an inverted U shape when viewed from the axial direction of the holding pin, has a curved cross-sectional shape, and the width of the groove in a cross section passing through the axis of the holding pin is the convex portion. The centrifuge according to claim 1, wherein the centrifuge is less than half of the diameter of the centrifuge.
The centrifuge according to claim 1 or 2, wherein a cross-sectional shape of the groove in a cross section passing through the axis of the holding pin is hemispherical.
The guide surface extends from the pin receiving portion formed in a semi-cylindrical surface substantially in parallel downward, and is formed by a rib for guiding attachment of the bucket to the convex portion. Item 4. The centrifuge according to any one of Items 1 to 3.
The centrifuge according to claim 4, wherein the groove portion is continuously formed from the pin receiving portion so as to be in contact with substantially the entire guide surface.
The centrifuge according to claim 5, wherein an interval W <b> 1 of the guide surface in the direction orthogonal to the mounting direction of the bucket on the guide surface satisfies W <b> 1> 2 G with respect to a width G of the groove.
For a centrifuge having a swing rotor body mounted on a drive shaft of a centrifuge, a plurality of holding pins arranged on the swing rotor body, and a plurality of buckets arranged so as to be swingable by being hooked on the holding pins The holding pin is a convex portion formed on the swing rotor main body and has a cylindrical surface on the outer periphery, the bucket has a concave portion corresponding to the convex portion, and the concave portion of the bucket Is formed with a guide surface formed by two surfaces facing the tip surface of the convex portion, the pin receiving portion, and the opposing surface along the boundary with the guide surface. A centrifuge swing rotor comprising a groove portion formed continuously and a groove portion whose depth direction is the axial direction of the holding pin, and a flat portion formed in a portion surrounded by the groove portion.
A side view as viewed from the axial direction of the holding pin has an inverted U-shape, and the tip surface of the holding pin and the flat portion face each other at a minute interval in the swing axis direction when the bucket swings. The swing rotor for a centrifuge according to claim 7.