JPS621770B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a rotationally symmetrical disc, the central region of which is formed into a concave portion concave toward the inside of the cylinder, and a circle constituting the concave portion. At least a portion of the plate surface area has at least one disk having a conical surface, and the disk has an annular appendage extending parallel to the cylindrical wall on its outer periphery, and the annular appendage extends parallel to the cylindrical wall. The invention relates to a centrifuge drum which is tightly fitted into the inner diameter of the centrifuge drum and which is connected to the inside of the cylindrical wall along the annular surface of the annular appendage.

[Prior art] The centrifugal drum as described above is disclosed in the West German Patent Publication No.
It is disclosed in No. 2033714.

Centrifuge drums such as those described above are used, for example, to centrifuge mixtures of fluids of different molecular weights.

For this purpose, centrifuge drums are generally made of high strength materials and loaded at high speeds close to the limit of material failure. Centrifuge drums, in turn, require careful dynamic interpretation and processing to the narrowest tolerances to eliminate local overload, unbalance, and seam problems.

The technique described above is characterized in that the disc formed as the lid is made from a high-strength, expensive die-forged part, is tightly fitted into the centrifuge drum, and is fixed to the centrifuge drum by electron beam welding. Centrifuge drums are known.

In the welding method, the electron beam passes through the drum wall from the outside at the point of maximum compression. The rotation of the centrifuge drum creates a molten pool at the edge of the lid that is approximately 1 mm deep and revolves around the longitudinal axis of the drum.
This first causes a widening of the more elastic drum tube wall and then a contraction, so that the region where the initial stress has occurred is brought into a state of stress that cannot be ignored. (The end of the drum tube wall is widened to a larger diameter by attaching a disk with a larger diameter than the drum tube wall to the inside of the drum tube wall. After welding, the drum tube wall is expanded to a larger diameter. (The stress field in the expanded region transforms into another unknown stress field due to thermal effects.) Furthermore, this structure requires the input of relatively expensive materials.

In other known constructions, the lid is shaped like a pot and is connected to a cylinder at the free end of the cylindrical part of the lid. For this purpose, it must in particular be achieved that the extent of the cylinder and the extent of the edge of the cylindrical part of the lid are approximately equal and that no significant bending stresses occur at the joint. On the other hand, a joint located in the cylindrical part far from the bottom of the pot-shaped lid is disadvantageous, since as a rule the joint area is weak in strength.

The fused region of such a joint is not self-supporting. Therefore, such a joint can be made by the bottom of the lid, which is at a lower stress level, than by the cylindrical part of the centrifuge drum, where additional stress on one part would reduce the load-carrying properties of the whole cylinder. This can be supported much more favorably.

[Problem that the invention seeks to solve]

Therefore, the problem to be solved by the present invention is a rotationally symmetrical disk whose central region is formed as a concave portion concave toward the inside of the cylinder, and at least a portion of the disk surface area constituting the concave portion. has at least one disc that is a conical surface, the disc has an annular appendage extending parallel to the cylindrical wall on its outer periphery, and the annular appendage is an interference fit on the inner diameter of the cylindrical wall. A centrifuge drum which is connected to the inside of the cylindrical wall along the annular surface of the annular appendage, which does not exhibit any significant stress concentration when loaded in the area of the disk-rotor connection. The object of the present invention is to provide a centrifuge drum that does not generate

[Means for solving problems]

As a result of research to solve the above-mentioned problems, the inventor of the present invention has determined that the bending moment of the centrifuge drum at the joint part of the centrifuge drum at the joint part between the annular appendage and the cylindrical wall of the centrifuge drum is to the bottom of the disc such that the movement of the disc 12 due to centrifugal force tends to change the disc shape with a concave central region to a disc shape with a less concave central region. Place it as close as possible,
Furthermore, the inventors have discovered that the desired object can be achieved by configuring the support portion of the cylindrical wall of the annular appendage to be outside the area of the joint, and based on this knowledge, the present invention has been completed. . That is, the centrifuge drum of the present invention is a rotationally symmetrical disc, and
The central region is formed as a concave portion concave toward the inside of the cylinder, and at least a portion of the disc surface region constituting the concave portion is a conical surface.
the disk has an annular appendage extending parallel to the cylindrical wall on its outer periphery, the annular appendage being tightly fitted to the inner diameter of the cylindrical wall, and having an annular surface on the annular appendage; In a centrifuge drum which is connected to the inside of the cylindrical wall along It is located as close as possible to the bottom of the disc so that it is essentially offset by the movement of the disc due to centrifugal force which tends to change the shape of the concave disc to a less concave shape in the central region. , and the support of the cylindrical wall of the annular appendage is outside the area of the joint. Thus, in the present invention, the annular appendage of the disc is welded to the cylindrical wall.

In the present invention, the conical slope of the disk is then directed toward the center of the centrifuge drum.

Next, in the present invention, a collar is connected to the annular appendage, the end surface of the cylindrical wall is in contact with the collar, and the end surface of the cylindrical wall is welded to the collar.

According to the invention, the lid can be made economically using thin sheet metal, and the annular appendage can be formed by bending the ends of the disc.

In the centrifuge drum of the invention, the cylinder, which is contracted onto the annular appendage with an interference margin, is supported in the area of a portion of the annular appendage. Since the maximum bending moments occur in this support, a joint with only low bending stresses is obtained if the cylinder and the annular appendage are joined together, for example by welding, outside the area of this support.

In the centrifuge drum of the present invention, the disk is a separating wall inside the drum and also a lid closing off the inner chamber. Of course, the drum may also be provided with multiple separating walls and/or lids. A disk of machined sheet metal or a disk of deep-drawn sheet metal can be provided for the dual purpose. A cylindrical annular appendage can here be formed on the outer contour of the disc.

In discs designed as lids, the disc with the bottom surface is connected to the end face of the cylinder, while the annular appendage projects into the cylinder. The annular appendage can be provided with a collar in the region of the height of the bottom surface, and the end surface of the cylinder is aligned with this collar,
Welded.

This technique of weld seam formation is somewhat comparable to I-impact welding directly facing the electron beam. Therefore, there are the following advantages over pipe wall penetration welding that has been performed up to now.

(1) The molten volume is reduced to approximately one third of that of a conventional welded seam.

(2) Shrinkage stress and distortion are reduced.

(3) The mass of the molten material, which is not self-supporting, is considerably low, meaning that the applied loads are applied to areas that are not disturbed by external forces.

(4) Exists based on a constant stress between the cylinder and the lid,
In addition, the changing stress conditions during welding cause only small movements in the cylinder and lid due to changes in the stress field.

(5) The always unavoidable notches, tears and other damage on the end faces of highly loaded cylindrical walls can be over-welded.

(6) Since the impact welding part to be welded can be seen from the outside, it is possible to accurately prevent the welding sol state.

By eliminating through-wall welding, there is no longer a need to join the cylinder and lid by high-energy and costly electron beam welding.

[Effect]

The invention is based on the knowledge that the joint between a disk and a cylinder made by electron beam welding, particularly in the area of the weld seam, is the weakest tube section. The poor strength of the joints is due in part to the fact that the components of the centrifuge drum (discs and cylinders) are age-hardened by welding in the area of the weld joints.
This is due to a decrease in the strength of the material. This weld seam and narrow region of the cross-section of the cylinder are in the molten red-hot state of the material, where the fracture strength of the material is approximately half that of the age-hardened region. On the other hand, during the operation of the centrifuge drum at the joint of the cylinder, a multiaxial stress state with a small principal stress difference and a high stress concentration occurs, and the multiple high stress concentrations are caused by melting red-hot soft materials. This is due to an excessively large elastic deformation being caused at a certain point.

In contrast, according to the present invention, bending stress in the meridian direction of the cylinder is hardly generated at the joints, which are weak parts of the rotor during driving, especially when driving a regular centrifuge drum. No meridional elastic deformation of the material within the soft region occurs.

During normal centrifuge drum drive, the radial movement of the free end of the annular appendage causes a certain tilt angle change at the joint, which tilt angle change causes almost no bending moment at the joint. It does not occur in That is, the cylinder wall is deformed to a shape that limits the transmission of forces from the cylinder to the disc to radial annular loads.

Also, the tangential stress concentration is sufficiently reduced so that the stress state of the centrifuge drum over the length of the cylinder has an overall lower stress level and a stronger uniaxial tendency. This means that the cylindrical material can freely exhibit greater deformation capacity in the main load direction (tangential direction), and the risk of stress failure due to multiaxial stress states with small principal stress differences is almost eliminated. give birth to

In the centrifuge drum of the present invention, the cylindrical portion is expanded in the radial direction by centrifugal force while the centrifuge drum is being driven to rotate, while the disk does not expand in the radial direction to the same extent as the cylinder, so the axis of the cylinder is The central portion in the direction is wider than both ends of the cylinder, and the ends of the cylinder are inclined, so that the cylinder stands up from the support. The radial movement of the free end of the annular appendage of the disc compensates for the angular torsion of the cylinder at the joint, so that the joint remains at least free from bending stress, and said movement It is not transmitted to the cylindrical wall beyond the cylindrical support provided in the cylindrical wall. Therefore, no load is applied to the cylinder by the disk.

In the present invention, as a result of the movement of the annular appendage of the disk, the inclination of the conical surface of the disk becomes gradual during rotation due to its own mass and the radial centrifugal force from the cylindrical wall. Become flat. At this time, the disk generates radial and circumferential stress, and the radial stress in the middle portion of the disk is more dangerous than the circumferential stress. However, since the disk has a conical shape, the stress in the radial direction of this intermediate portion is alleviated by flattening the disk, thereby preventing its breakage. Moreover, when the disc is deformed flat, its middle part bulges in the axial direction, thus compensating for the bulging and axial shortening of the cylindrical wall during rotation and keeping the length of the drum constant.

In the present invention, then, the joint is located close to the bottom of the lid, so that relatively low tangential stresses can take up the additional loads of the weld seam in this joint.

The tangential stress and the radial extent of the outer annular appendage increase away from the lid base until it becomes a pure tube stress. The conically shaped lid base, which is loosened under rotational loads, folds back the annular appendage inwardly, thus correcting a portion of the radial extent of the annular appendage. As a result, the tangential stresses, which are normally actually high in the region of the annular appendage, are reduced.

Since no bending moment acts on the cylindrical end when it is at rest, no cylindrical warping, ie, no meridional plastic deformation, occurs during welding. The fusion volume of the welded joint at the cylindrical end face is reduced to approximately one third of that of a conventional weld in known constructions. Thereby, the original stress of the disk (the stress field caused by the action of centrifugal force due to the mass of the disk and its shape) is reduced, the mass that is not self-supporting is smaller, and the eccentricity of the disk is reduced. Furthermore, in the case of such joints, obstacles that actually occur, notches or micro-cracks in the cylindrical end face can easily be over-welded. Furthermore, the state of sol in the weld seam can be effectively prevented since the joint can be observed from the outside.

〔Example〕

The drawings schematically depict embodiments of the invention.

Figure 1 is a cross-sectional view of the centrifuge drum, Figure 2 is a cross-sectional view of the centrifuge drum.
FIGS. 3 and 4 are partial cross-sectional views of the front of the illustrated centrifuge drum, and FIGS. 3 and 4 are partial cross-sectional views of the joint shown in the second figure.

The centrifuge drum 10 has a cylindrical wall 11 and two disks 12 arranged as lids and arranged at the ends of the cylinder.
and 13, and are rotatably supported by ball bearings and magnetic bearings. The first disc 12 has a shaft 1 for a drive 17, which is shown schematically.
4 is fixed. The second disk 13 carries a magnet 15, which together with a fixed magnet 16 forms a magnetic bearing. Furthermore, a separating disk 18 is provided inside the cylinder.

The disc 12 connected to the shaft 14 is shown in more detail in FIG. It consists of a thin sheet of metal,
For the outer periphery, an annular appendage 20 is articulated and molded to form a recess 22 in the central region pointing towards the inside of the cylinder. The conical slope 21 is inclined towards the center of the cylinder. A collar 23 for joining the lid and the cylindrical wall is provided at the level of the bottom of the lid of the annular appendage 20.

The disc 12 thus formed as a lid is tightly fitted into the cylindrical wall 11 . At that time, the cylindrical wall 1
1 is expanded. The modification of the cylindrical wall is shown in detail in FIG. 3, which shows a machined solid lid disc 12' instead of a thin sheet metal lid.

When the cylindrical wall 11 on the annular appendage 20' is pushed out, the support part 25 of the annular appendage 20' is wrapped by the cylindrical wall, and then the end surface of the cylindrical wall 11 and the cylinder of the annular appendage 20' The diameter of the cylindrical end increases until the distance between the supports 25 reaches a certain value,
The diameter then decreases again. As a result, a cylindrical support 25 is formed in the corner region of the annular appendage 20', in which bending stresses of the cylindrical wall 11 essentially occur. The end of the cylinder in the immediate vicinity of the annular appendage 20' is brought into abutment with the disc without any bending stress being created by the cylinder being further spread apart at the annular appendage 20'. If both cylinder parts are spread out uniformly, the distance between the cylinder end face and the support part 25 is approximately 3 when the cylinder has a diameter of 15 cm and the wall thickness is 0.4 mm or less.
It becomes mm.

Under these conditions, the free end of the cylinder used as the joining area does not have any bending stresses. Also, this stress condition is made less essential by further welding the cylindrical end to the lid. The joint portion 26 exists between the end surface of the cylindrical wall 11 and the joint collar portion 23 .

In FIG. 3, the joining area between the cylindrical wall 11 and the disc 12' is shown in a static state, the cylindrical wall 11 being connected to the disc 12'.
2' is supported by a support part 25 consisting of a corner of an annular appendage 20'.

After an acceleration period of the cylinder (acceleration period in which the cylinder is accelerated to maximum velocity), the stress field changes. During normal operation, with a fairly mounted disk 12', a situation is obtained in which little or no bending stresses in the joints are observed. As shown in Figure 4, the cylinder is wider than the disk 12'. The free end of the cylindrical wall is held to the disk by a welded joint 26. In this case, the angular torsion α caused by the cylindrical wall at the joint is offset by the angular torsion β of the disc of approximately the same value. As a result, the joint, which is the weakest part of the cylinder, is loaded to the minimum possible, and the stress effects are not as strong as under the conventional maximum permissible rotational speed limit.

In the case of a disk 18 fixed in a cylinder, a disk that is inserted more strongly or a disk that has been made of a suitable material will be expanded due to centrifugal force in addition to the angular twist due to its position inside the cylinder, and as a result, the cylinder will The expansion of the body plate is almost corrected.

[Effects of the Invention] As described in detail above, according to the present invention, bending stress in the meridian direction of the cylinder can be prevented from occurring at the joints, which are weak parts of the rotor, during driving, especially during driving of a regular centrifuge drum. Almost no meridional elastic deformation of the material in the soft region of the joint occurs.

During the operation of a regular centrifuge drum, a certain change in the angle of inclination occurs at the joint due to the folding of the annular appendage, and the cylindrical wall directs the transmission of forces from the cylinder to the disc in the radial annular shape. The cylindrical material is deformed to a load-limiting shape, no bending moments occur at the joint, and the tangential stress concentration is sufficiently reduced so that the material of the cylinder is Large deformability can be freely exerted, and the risk of stress fracture due to multiaxial stress states is almost eliminated.

Also, during the rotational drive of the centrifuge drum, the cylinder is expanded by the higher centrifugal force and lifted off the support, but the folding movement of the annular appendage of the disk compensates for the angular twist of the cylinder at the joint. No additional load is applied to the cylinder from the disk.

Furthermore, since no bending moment is applied to the cylindrical end in a stationary state, no cylindrical warping occurs during welding. Also, the molten volume of the welded joint at the cylindrical end face can be reduced by approximately one-third of that of a conventional weld in known constructions, thus reducing the source stresses, reducing the non-self-supporting mass, and reducing the disc's Eccentricity can be further reduced.
Furthermore, notches or minute cracks in the cylindrical end surface can be easily over-welded, and since the joint can be seen from the outside, the state of sol in the weld seam can be effectively prevented.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the centrifuge drum, Figure 2 is a cross-sectional view of the centrifuge drum.
FIGS. 3 and 4 are partial cross-sectional front views of the illustrated centrifuge drum, and FIGS. 3 and 4 are partial cross-sectional views of the joint shown in FIG. 10...Centrifuge drum, 11...Cylindrical wall, 1
2, 12', 13...disc, 14...shaft, 15...
... Magnet, 17 ... Drive device, 18 ... Separation disk, 20, 20' ... Annular appendage, 22 ... Recess, 23 ... Flange, 21 ... Slope.

Claims (1)

[Claims] 1. A rotationally symmetrical disc, the central region of which is formed as a concave portion concave toward the inside of the cylinder, and at least a portion of the disc surface region constituting the concave portion is a conical surface. at least one disk, the disk having an annular appendage extending parallel to the cylindrical wall on its outer periphery, the annular appendage being a tight fit on the inner diameter of the cylindrical wall, and having an annular In the centrifuge drum, the joint 26 of the annular appendage 20 and the cylindrical wall 11 is connected to the inside of the cylindrical wall along the annular surface of the appendage.
However, while the centrifuge drum 10 is being driven, the joint portion 2
The bending moment of the centrifuge drum 10 at 6 is essentially offset by the movement of the disk 12 due to the centrifugal force which tends to change the shape of the disk with a concave central region to a shape with a less concave central region. so that the support 2 of the cylindrical wall 11 of the annular appendage 20 is located as close as possible to the bottom of the disc and
A centrifugal drum characterized in that 5 is outside the area of the joint 26. 2. Centrifuge drum according to claim 1, characterized in that the annular appendage 20 of the disk 12 is welded to the cylindrical wall 11. 3. Centrifuge drum according to claim 1 or 2, characterized in that the conical slope 21 of the disc 12 is directed towards the center of the centrifuge drum. 4 A joining collar 23 is connected to the annular appendage 20, and the cylindrical wall 1 is connected to the joining collar 23.
The centrifuge drum according to claim 1, 2, or 3, wherein the end surfaces of the cylindrical wall 11 are in contact with each other, and the end surface of the cylindrical wall 11 is welded to the joining collar portion 23. .