JP3759968B2 - Method of constructing shaft and paddle assembly for mixer and processor and shaft and paddle assembly - Google Patents

Description

[0001]
[Industrial application fields]
The present invention is a twin screw mixer (twin screw mixer), relates to an extruder or processor (processor), in particular, it relates to new and useful improvements in methods of making the paddle shaft assembly. This paddle shaft assembly is used in twin screw mixers or blenders to allow increased mixing power and to limit the amount of processing material that travels through such continuously operating machines. It is not accompanied by a decrease in the free volume in the brazing machine.
[0002]
[Background Art and Problems to be Solved by the Invention]
The present invention was developed for use in, for example, the plastics industry and for twin screw mixing and compounding machines of the type illustrated in the assignee's prior US Pat. Nos. 3,195,868 and 4,826,323. . A relatively large machine of this type preferably uses shafts driven by a hydraulic motor and individual paddles or worm parts that are on these shafts and wipe each other aligned in the radial direction of the shaft. It is. Both the paddle and the warm part are included in the term “paddle” used in the text in the following description. In machines with this property, the shaft having a permanently fixed paddles, paddle completely mutually wiping each other, and at the same time, in order to wipe the complete interior of the barrel bore paddle is activated, is rotated in the same rotational direction at the same speed Must-have. Paddle used is Whether a either a single-lobe or multi-lobe (lobe) type, geometric graphical outer shape, paddle components of the counterpart as mutual wiping each other resulting in any surface of the paddle components These geometric shapes are directly influenced by the diameter of the barrel holes relative to the center spacing of the shafts. Normally, to increase the power supplied to the paddles of such machines for mixing purposes and increased throughput, the dimensions of both the paddles and the shafts driving those paddles can be increased to accommodate the increased load. It is necessary to carry at the level . However, to increase the diameter of a shaft for a machine with a specific size barrel, it is necessary to change the hole-to-center spacing ratio of the twin screw paddle assembly, which reduces the width of the assembly. Will increase. Along with this, increased in relation to the diameter of the shaft wall thickness of the paddle components is increased, thus the paddle elements are thicker, the free volume of the machine to the diameter of the same hole is greatly reduced. Thus, conventional machines intended to cause an increased product processing rate can not tolerate increases in power is required to process the material.
[0003]
Typically, in-volume toothed splines are used today to transmit power from shaft to paddle, as disclosed in prior US Pat. No. 4,591,487, but various key and hexagonal shaft profiles are also available. Proposed. While not all are considered to be closely related to the field of the present invention, Applicants are aware of the following prior patents, which are incorporated herein by reference.
US Pat. No. 2,668,756 Kearney US Pat. No. 2,777,353 Willis US Pat. No. 3,584,667 Leyland US Pat. No. 4,073,013 Blatch US Pat. No. 4,236,833 Brach US Pat. No. 4,269,246 Larson et al. US Pat. No. 4,591,487 Flitch US Pat. No. 5,171,117 Seidur
[Means for Solving the Problems]
The present invention relates to supplying greater power at lower stress levels to a mixer paddle in a pre-sized mixer barrel that currently uses the most state of the art involute spline shaft in the field. While maintaining the proper hoop strength for the paddle, the method and apparatus of the present invention is a series of lobes that connect as a tangent as a contour for the inner bore of the mixer paddle. Use one that alternates with the root recess. These align with lobes and valley bottom recesses provided on the outer periphery of the mixer shaft. In the case of a specific size mixer or steam liquefier with a specific size barrel, increased power can be generated. Since most processing in such a processor is in horsepower / pound, more material can be moved through the processor with increased horsepower to process it.
[0005]
One of the main objectives of the present invention is to increase the power delivered without reducing the free volume of the mixer and without limiting the material throughput.
[0006]
A further object of the present invention is to promote the use of more reliable equipment without the risk of imposing greater load stresses and without fear of potentially unreliable equipment operation with a large premature failure rate. is there.
[0007]
It is a further object of the present invention to provide a twin screw mixer in which the shaft and paddle assembly can produce greater power at lower stress levels than in current machines and can greatly increase production rates.
[0008]
A further object of the present invention is that some of the lobe contours described below may be used even if the stress is increased elsewhere to provide a reduced stress ratio, taking into account appropriate and practical manufacturing tolerances. The present invention provides a twin screw mixer having a paddle and shaft assembly that reduces the shear stress imposed at critical paddle locations.
[0009]
Yet another object of the present invention is a higher strength shaft and paddle assembly that transmits power by using an optimal number of new lobes and lobe valley recesses to form a profile. It is intended to provide a system that can reduce the total stress generated in the process.
[0010]
Yet another object of the present invention is to provide an assembly that allows the transmission of greater torque than previously possible with identically sized mixers.
[0011]
Yet another object of the present invention is a system of the disclosed characteristics that receives increased torque without the paddles spreading and interfering with the operation of the paddles in their wiping relationship with the barrel wall. To design the one with the proper hoop strength.
[0012]
Other objects and advantages of the present invention will become apparent by referring to the attached drawings and the following description.
[0013]
【Example】
1 and 2 for the description of the prior art mechanical apparatus, the mixer-processor shown generally as M has an upright strut 10a as a whole with MB as a mixer-processor. It is shown as having a platform 10 that supports the illustrated mixing barrel. The mixing barrel MB, as particularly shown in FIG. 2, defines a mixing chamber 11 which has the shape of the number 8 and has the shape of the number 8 in which the twin mixing shafts 12 and 13 are rotated. ing.
[0014]
The mixing shaft 12, 13 is fixed paddle 20, 21 of the screw or worm forms mutually wiping each other. Furthermore, provided as a lens-shaped machine element also paddles 22, 23 mutually wiping each other contours shown in FIG. 2, it is fixed to the mixing shaft 12. And that multiple pairs of coupling the Hare paddles 22 radially wipe each other is angularly displaced from one another to define a spiral shape continuous, cross-section of the paddles 22 and 23 are lens-shaped as shown in FIG. 2 the contours and defining child should leave understood.
[0015]
As shown particularly in FIG. 2, the mixing shaft 12, 13 has an outer contour of the involute gear, the outer contour of these involute gear meshes with involute gear contour provided in the hole of the paddle 22. Contours of these involute gears, the teeth 24 and valleys 25 provided on the mixing shaft 12, 13, the paddles 20, 21 and 22, 23, provided on the contour of the shown to pores with a BR as a whole, the teeth being interdigitated and a 26 and valleys 27. In particular, as shown in FIG. 3, the involute teeth 24 , 26 respectively provided in the contours of the mixing shaft and the paddle hole have a convex side wall 28 on the tooth 24 and a concave side wall 29 on the tooth 26. Side walls 28 of the convex surface is bonded to the inner circumferential surface 31 i.e. root of involute gear contour an outer circumferential surface 30 of the teeth 24, formed on the inner peripheral surface 31 is the radius on which from the center c of the mixing shaft 12 and these outer peripheral surface 30 Has been . Similarly, the concave side wall 29 connects the peripheral surface 32 of the tooth 26 with a valley bottom 33 provided in the involute profile of each paddle hole . As shown in FIG. 3, the peripheral surface 32 and the valley bottom surface 33 are aligned with the inner peripheral surface 31 and the outer peripheral surface 30, respectively, and a small sliding gap is provided between the peripheral surfaces for manufacturing and assembly purposes. .
[0016]
FIG. 4 shows different contours, in which the same reference numerals are used to indicate the same parts of the machine. In FIG. 4, the mixing shafts 12 and 13 are provided with lobes 34 separated by recesses 35. These recesses and lobes are provided in lobes 36 and recesses 37 provided alternately in the contour of the hole BR of the paddle. Mating. These lobes and recesses have sinusoidal contours, and the lobes 34 and recesses 35 are formed from curves of the same radius that are completely tangential to each other . The contours of the hole lobes 36 and recesses 37 are the same and align with the recesses and lobes of the mixing shaft, except for the manufacturing and assembly gaps described above. The torque transmission by the profile shown in FIG. 4 allows for stronger power than the currently used prior art involute profile , and the disclosed 12 lobe profile allows for less stress in critical areas. To do.
[0017]
In FIGS. 5 and 6, a preferred embodiment of the present invention is illustrated, again using the same reference numerals to identify previously identified components. 5 and 6, the hole contour BR of each element or paddle 22 and 23 is shown as having twelve alternating lobes and valley bottom recesses generally indicated by 38 and 39, respectively. ing. An intermediate portion 39 a of the recess 39 is located on a radius 40 from the hole center 41. The mixing shaft 12 has matching lobes 42 and valley bottom recesses 43. As FIG. 6 shows, each of the valley bottom recesses 43 has an intermediate surface 43a located on a radius 55 from the hole center or axis center 41 and the radius 55 is 7.5 at the end of each intermediate surface 43a. It should be noted that an angle of degrees is formed. As shown in FIG. 6, the lobe 38 of the paddle 22 has a matching intermediate surface 38a that forms the same angle as described above.
[0018]
Needless to say, there is a normal operating slip gap between the mating surfaces of the paddle and mixing shaft that allows the manufacture and assembly of these components. To couple the recess intermediate surface 43a that is defined on the surface 42a and the radius 55 of the axis that is defined on the radius 40, and an arc-shaped corner radius 42b connected tangentially on the lobe 42, the intermediate An arc corner radius 43b that is tangentially connected to the surface 43a is provided. Surfaces 38b and 39b connected in alignment are provided on the contour of the hole BR of the paddle .
[0019]
In the exemplary paddle disclosed in FIG. 6 where dimensions are used to describe the particular configuration of the paddle and mixing axis, the arcuate corner radius or corner surface 42b is centered on a point 44 located on the radius 54. It will be noted that it is defined on a radius of 0.375 mm (0.0148 inch). Aligned and connected surface 38b is defined on a radius of 1.874 mm (0.0741 inches) from point 45 positioned to cause contact between aligned and connected surface 39b and intermediate surface 38a. Yes. The relationship between the arc corner radius 42b and the radius defining the aligned and joined surface 38b is linear and in the preferred embodiment is 5 to 1. Needless to say, the arcuate paddle hole face or aligned and connected surface 38b and the arced corner radius 42b are aligned with the arced corner radius 43b and the aligned and connected surface 39b, respectively.
[0020]
The outer surface of the paddle has an intermediate surface 56 defined about a radius 46 and an arcuate portion 47 extending from and in contact with the intermediate surface 56, the arcuate portion 47 having an angle of 11.25 ° from the radius 46. It should be noted that it is defined around a radius 48 (taken from point 49) facing each other. An end face 50 is defined on a radius 51 from the hole center 41.
[0021]
In FIG. 7, the paddle disclosed in FIG. 6 except that the ratio between the paddle hole surfaces or aligned and joined surfaces 38b and 39b is 3: 1 rather than 5: 1 in FIG. Also disclosed are paddles and mixing shaft assemblies that are very similar to the mixing shaft assembly. In FIG. 6, the transmission stress in the component was further reduced by changing the valley radius of 43b as a function of the tip radius of the lobe at 42b in a linear fashion. Better results were achieved in the format of FIG. 6 than in the format of FIG. However, the form of FIG. 7 is superior to the sinusoidal profile disclosed in FIG. 4, which is superior to the prior art involute profile disclosed in FIGS. 1-3.
[0022]
Next, when compared to FIG. 2 and FIG. 5, which are not accurate but close to scale, a considerably larger free volume, ie a net volume greater than about 23%, is provided in the mixing chamber 11 in FIG. The mixing shaft and paddle in FIGS. 2 and 5 transmit the same power, but because of the improved stress characteristics, the mixing shafts 12 and 13 in FIG. 5 can be somewhat smaller. This allows the center-to-center distance of the mixing shafts 12 and 13 to be shortened in FIG. 5, thus allowing the paddles 22 and 23 to be considerably thinner.
[0023]
It should be emphasized that the contours developed by the applicant are developed as a result of the balance of the various stresses that the assembly is subjected to when performing its functions. In the case of Applicant's FIG. 6, stress was considered to provide a stress balance that allowed a greater force to be transmitted by the test. One of the tests that are important to the assignee's assignee in the market for the twin screw device is torsional stress analysis and a shear force concentration defined as the shear stress at point B divided by the shear stress at point A. It is what is called. Because of the involute profile of FIG. 3 and the favorable profile shown in FIG. 6, point A is located in the valley diameter recess, while point B is located in the root of the tooth.
[0024]
The stress concentration for the involute convolution shown in FIGS. 2 and 3 in units of kg / cm ² (psi) was 0.127 (1.81) in the tests performed. For a 12 splined involute profile it was higher at 0.148 (2.11). In contrast, the comparable stress concentration for the contour of FIG. 4 was 0.096 (1.37). For a profile (FIG. 7) using a 3: 1 root root to tip radius ratio, the stress concentration is 0.089 (1.27) and the root root to tip radius ratio is 5 When it was 1: 1, the stress concentration was reduced to 0.086 (1.23). Applicant, in the preferred embodiment of the present invention disclosed in FIG. 6, the dimension of the lobe valley radius at point B to avoid a failure situation where the shear stress at point B exceeds the yield strength when sheared. Increased significantly. The hoop strength of the paddles 22 and 23 is also a consideration and must be maintained within acceptable values. In Applicants' embodiment, sufficient material remains between the lobe projections of the mixing shaft and the paddle wall portion or intermediate surface (56) to maintain sufficient hoop strength.
[0025]
In operation, it is assumed that the machine shown in FIG. 1 is a machine that uses Applicants' invention. The material to be mixed is continuously fed through opening 17 and advanced by screws or paddles 20 and 21, more intimately mixed by elements or paddles 22 and 23 and continuously discharged at 20. In prior art machinery, up to about 75 horsepower can be used to obtain a production rate of about 900 kg (2,000 pounds) per hour. According to Applicant's new method, the horsepower can be safely doubled by keeping the mixing shaft and paddle the same dimensions and the operating speed the same, and consequently 2 Double the material can be charged through the opening 17 and can be mixed with increased power. On the other hand, about 50% of the available space was previously filled with material, but now about 75% can be filled. The relationship between mixed horsepower and production is linear.
[0026]
In short, from the consideration of paddle torsional stress, the contours disclosed by the inventor disclosed herein are clearly superior. When the gap had a property of 0.127 mm (0.005 inch), it was called contact stress strength, but sufficient hoop strength was maintained. Applicants have been able to achieve essentially greater throughput with a contour that is superior in terms of torsional stress analysis, while retaining other stresses that are within acceptable limits.
[0027]
It should be understood that the described embodiments are merely illustrative of various forms of the invention, and that the invention is defined in the claims that envision various modifications within the spirit and scope thereof. .
[Brief description of the drawings]
FIG. 1 is a schematic side partial longitudinal sectional view of a twin screw mixer of the type disclosed in some of the assignee's previous patents.
FIG. 2 is an enlarged schematic partial cross-sectional view taken along line 2-2 of FIG. 1 disclosing an involute gear profile for the paddle hole and the periphery of the mixing shaft.
FIG. 3 is an enlarged schematic partial cross-sectional view of a paddle hole involute spline structure according to the current prior art.
FIG. 4 is an enlarged cross-sectional view similar to FIG. 2 but disclosing a true sinusoidal, lobed profile.
FIG. 5 is similar to FIG. 2 of a preferred embodiment of the mixing shaft paddle assembly of the present invention illustrating the increased throughput available and utilized in a mixer barrel of approximately the same dimensions as FIG. Schematic.
FIG. 6 is an enlarged cross-sectional view of only one of the preferred paddle and mixing axes, with a lobe and valley bottom corner radius ratio of 5: 1.
FIG. 7 is an enlarged partial cross-sectional view of another embodiment in which corner tangent corner radii are used in a 3: 1 ratio.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Mixing chamber 12 Mixing shaft 13 Mixing shaft 20 Paddle 21 Paddle 22 Paddle 23 Paddle 34 Robe 35 Recess 36 Robe 37 Recess 38 Robe 38a Aligned and connected surface 39 Recess 39b Aligned and connected surface 42 Robe 42b Arc-shaped corner Radius 43 Recess 43b Arc corner radius

Claims (13)

In a method for constructing or reconfiguring a drive assembly comprising shafts (12, 13) and elements (22, 23) in mutual drive relationship,
a) Process of forming a hole (BR) in the element (22, 23), the hole being formed on a large radius and a smaller radius (40, 55) from the axis of the hole (BR) A process that is a contour having machine element lobe-shaped protrusions (38) having circumferential surface portions (38a, 39a) located alternately and machine element valley bottom recesses (39);
b) A shaft lobe-like projection (42) and a shaft valley bottom recess (43) that mesh and align with each other are formed in the shaft (12, 13), and the lobe-like projection (38) of the element (22, 23) and The element (22, 23) is mounted on the shaft, with the valley bottom recess (39) and the valley bottom recess (43) of the shaft (12, 13) and the lobe-shaped projections (34, 42) engaging with each other. The process of
c) forming arc-shaped corner portions (38b, 39b) in the element lobe-shaped protrusions (38) and the element valley bottom recesses (39) of the element holes (BR), and these arc-shaped corners; The portion connects the surface of the element lobe-shaped protrusion (38) and the element valley bottom recess (39) and forms a pair of oppositely curved tangentially arcuate surfaces (38b, 39b). The arcuate surfaces are also tangentially connected to the peripheral surface portions (38a, 39a) of the element lobe-shaped projections (38) and the element valley bottom recess (39);
d) the arcuate corner portion (38b) of the elemental lobe projection (38) with a radius that is a multiple of the radius producing the arcuate corner portion (39b) of the element valley bottom recess (39); The stress concentration part is reduced by generating,
e) A contour that fits into the contour of the element valley bottom recess (39) and the element lobe protrusion (38) in the shaft lobe protrusion (42) and the shaft valley bottom recess (43) of the shaft (12). Are formed, and the shafts (12, 13), the lobe-shaped projections (38, 42) of the element holes (BR) and the valley bottom recesses (39, 43) are engaged with each other and matched to each other. And a method comprising: 2. The method of claim 1, wherein the element is a paddle (22, 23) for a mixer and processor, aligned radially on parallel axes (12, 13) at the same speed and in the same direction. Rotating paddles wipe each other and wipe the inside of the mixer or processor barrel (MB), which continuously receives material near one end (17) and discharges it near the other end (20a). In a method comprising a mixer chamber (11) comprising connected cylindrical holes,
c) a pair of such shafts (12, 13) provided with said shaft lobe-like projections (42) and shaft valley bottom recesses (43);
d) forming the element lobe-like protrusion (38) and the element valley bottom recess (39) on the plurality of paddles (22, 23);
e) The paddle element lobe-shaped protrusion (38) and element valley bottom recess (39) and the shaft shaft lobe-shaped protrusion (42) and shaft valley bottom recess (43) are engaged with each other and aligned. A plurality of the paddles (22, 23) are mounted on the shafts (12, 13);
f) A complete mixer chamber (MB) in which the shafts (12, 13) are wiped by the paddles (22, 23) by separating the axes of these shafts to provide a predetermined center-to-center distance between the shafts. A method characterized by additional processes that are accomplished and attached to a spaced parallel relationship. 2. The method according to claim 1, wherein the element and the shaft lobe-shaped protrusion (38, 42) and the element and the shaft valley bottom recess (39, 43) are respectively separated from the center (41) of the hole (BR). Intermediate peripheral surface portion tangentially connected to these element and axial arc-shaped corner portions between the arc-shaped corner portions (38b, 39b, 42b, 43b) each generated on a radius (40, 55) taken (38a, 39a, 42a, 43a). 2. The method of claim 1, wherein the multiple is 3: 1. 2. The method of claim 1, wherein the multiple is 5: 1. A drive assembly comprising shafts (12, 13) and elements (22, 23) in mutual drive relation,
a) The element (22, 23) has a hole (B) with an axis (41) coinciding with the axis of the axis. R), and this hole is contoured to receive such a shaft (12, 13) in drive relation;
b) The contour of the hole is an elemental lobe with alternating circumferential surface portions (38a, 39a) formed on a large radius and a smaller radius (40, 55) from the axis of the hole (BR) Having a protrusion (38) and a machine valley bottom recess (39),
c) The shafts (12, 13) are in meshed and aligned shaft lobe projections (42) and shafts respectively received in the element valley recesses (39) and element lobe projections (38) of the holes. It has a valley bottom recess (43),
d) The alternating element lobe-shaped protrusions (38) and element valley bottom recesses (39) include arc-shaped corner portions (38b, 39b), which arc-shaped corner portions are the element lobe-shaped protrusions (38). 38) and the surface of the element valley bottom recess (39) are connected to each other to form a pair of arcuate surfaces (38b, 39b) which are curved in opposite directions and are connected in a tangential direction, and these arc-shaped surfaces are also formed in the element lobe. Are connected tangentially to the circumferential surface portions (38a, 39a) of the machine-shaped valley bottom recess (39), and the arc-shaped corner portion (38b) of the machine-shaped lobe-shaped projection (36, 38) is Formed on a larger radius that is a multiple of the radius that formed the arcuate corner portion (39b) of the element valley bottom recess,
e) The shaft lobe-shaped projections (42) and the shaft valley bottom recesses (43) are contours that respectively fit the contours of the machine element valley bottom recesses (39) and the machine element lobe-shaped projections (38). A drive assembly that forms an intermeshing and aligning relationship between the lobes (38, 42) and the valley bottom recesses (39, 43) of the shafts (12, 13) and element holes (BR). . 7. An assembly according to claim 6, wherein a pair of said shafts (12, 13) are provided and a plurality of said elements in the form of paddles (22, 23) are radially aligned with each of said shafts. And is provided with a drive for driving the shaft in the same rotational direction at the same speed, the shaft and paddle comprising a plurality of interconnected parallel cylindrical holes that receive the shaft in the axial direction A drive assembly mounted in a mixer barrel (MB). 7. An assembly as claimed in claim 6, wherein there are twelve such elemental lobe projections (38). The assembly according to claim 6, wherein the element lobe-shaped protrusion (38) and the element valley bottom recess (39) are on a radius (40, 55) taken from the axis (41) of the hole (BR). The intermediate peripheral surface portion (38a, 39a) is formed, and the peripheral surface of the intermediate peripheral surface portion (38a) of the element lobe-shaped projection (38) is the intermediate peripheral surface portion of the element valley bottom recess (39). A drive assembly that is larger than the perimeter of (39a). 7. The assembly according to claim 6, wherein the assembly is in the form of a twin shaft mixer or processor having a mixer barrel (MB) with a material inlet (17) at one end and a material outlet (20a) at the other end. And
a) a pair of shafts (12, 13) extending longitudinally into the barrel (MB);
b) a mechanism for driving the shafts (12, 13) in the same rotational direction at the same speed;
c) The element is in the form of paddles (22, 23) provided with holes (BR), these holes having an axis (41) coinciding with the axis of the axis, and the axes (12, 13) Contoured to accept driving relationship,
d) The paddle hole contour (BR) is formed by the alternating element lobe-shaped protrusions (38) and element valley bottom recesses (39), and the arc-shaped corner portions (38b, 39b). An element-shaped lobe-shaped protrusion (38) and an arc-shaped connecting portion connecting the element-valley bottom recess (39), and the element-shaped lobe-shaped protrusion (38) has an arc-shaped connecting portion (38b). Tangentially connected to the arc-shaped connecting part (39b) of the recess (39),
e) Aligning shaft lobe projections (42) in which the shafts (12, 13) are received in the element valley bottom recesses (39) and element lobe projections (38) of the paddles (22, 23), respectively. And a drive shaft assembly having a shaft valley bottom recess (43). 11. An assembly according to claim 10, wherein an arcuate corner surface (38b) of the element lobe projection (38) is provided with a concave bottom of the element valley to reduce stress concentration in the paddle (22, 23). Multiple times the radius to produce the arcuate corner portion (39b) of the place (39) A drive assembly having a larger radius which is 9. The assembly of claim 8, wherein the multiple is 3: 1. 7. The drive assembly of claim 6, wherein the multiple is 5: 1.

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