CA1223136A - High torque drive means for two very close shafts and application thereof to a double screw extruder - Google Patents
High torque drive means for two very close shafts and application thereof to a double screw extruderInfo
- Publication number
- CA1223136A CA1223136A CA000450420A CA450420A CA1223136A CA 1223136 A CA1223136 A CA 1223136A CA 000450420 A CA000450420 A CA 000450420A CA 450420 A CA450420 A CA 450420A CA 1223136 A CA1223136 A CA 1223136A
- Authority
- CA
- Canada
- Prior art keywords
- gear
- drive
- shafts
- drive gear
- driving
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Extrusion Moulding Of Plastics Or The Like (AREA)
Abstract
ABSTRACT
An apparatus for rotationally driving two closely spaced parallel shafts comprises a driven gear on each shaft and two drive means for driving each of the driven gears. The shafts are constrained to rotate at the same speed by interengaging teeth of the driven gears or by an idler gear. Four independent motors are used to drive the shafts.
An apparatus for rotationally driving two closely spaced parallel shafts comprises a driven gear on each shaft and two drive means for driving each of the driven gears. The shafts are constrained to rotate at the same speed by interengaging teeth of the driven gears or by an idler gear. Four independent motors are used to drive the shafts.
Description
2 ~223:~3fi "HIGH DRIVE TORQUE MEA~S FOR TWO CLOSELY SPACED SHAE'TS
AND APPIICATION THEREOF TO A DO~BLE SC~EW EXTRUDER"
Thls invention relates to drive means capable of rotating two parallel adjacent shafts which are used, for example, in a double screw extruder for plastic materials.
In the case of two adjacent shafts rotating in opposite directions, the simplest way for rotating them is to transmit the entire torque of the motor only to one of the two shafts, and then impart a rotation to the second shaft by a pair of identical gears, each one - keyed to each shaft, such as to mesh with the other gear. On the other hand, if the parallel adjacent shafts must rotate in the same direction, the rotation imparted to the first shaft, by a single motor, is transmitted to the second shaft by means of an intermediate gear.
However, in these embodiments, the high speed of rotation of the shafts leads to severe wear and to very short life of the plasticizing screws. On the other hand a low speed would cause high torques and accordingly occasional hreakage. Further, when the distance between the shafts is very small, the gears must have very small pitch diameters.
In the last few vears, two ways have been developed to overcome this drawback.
The ~irst way consists of making shafts which are not parallel to one another but carry, for example, conical e~truding screws, so that at some distance from the cone apex the gears may have larger dimensions.
However, this complicates the entire construction.
A second approach is to separate the shaft actuation, by providing a reduction unit, in which each shaft directly receives from the reduction unit half of the total torque.
~ttempts were also made to increase the gear ; sturdiness by lengthening the latter or increasing their number. However, this also considerably adds to costs.
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~Z~3~L36 There~ore, it is the object of an aspect of the present invention to provide a structurally economical solution to the problem of driving two closely spaced parallel adjacent shafts.
According to the present invention, the above object has been achieved by providing that two parallel shafts, each fitted with a gear meshing with further gears, are each driven by at least two drive members.
In a preferred embodiment the drive members are units which are completely independent of one another;
that is having fully distinct motors.
In this case, preferably, the use of epicyclical reduction units which are readily commercially available is contemplated.
In an application of the invention to a double screw extruder for plastic materials, it is preferable that the housing containing the extruding screws is directly connected to the support of the th-rust bearings, without overstressing the drive box. Preferably, the connection is obtained by means of tie rods passing through the drive box.
For two shafts rotating in the same direction, the two gears mounted on such shafts are slightly spaced - apart from each other, while the drive members are synch-ronized by an idler gear meshing therewith.
An aspect of the invention is as follows:
An apparatus rotationally driving two closely spaced parallel shafts, comprising: a first driven gear on a first of said shafts; a first drive gear and a se~ond drive gear, said first drive gear and said second drive gear being for directly driving said first dri~en gear; a first independent drive means for driving said first drive gear and a second independent drive means for driving said second drive gear; a second driven gear on a second of said shaft; a third drive gear and a fourth :
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drive gear, said third drive gear and said fourth drive gear being for directly driving said second driven gear;
a third independent dr~ve means for drlving said third drive gear and a fourth independent drive means for driving said fourth drive gear; and synchronizing means for constraining each of said closely spaced parallel shafts to rotate at the same speed; whereby torque applied to said first driven gear by said first drive gear and by said second drive gear and to said second driven gear by said third drive gear and by said fourth drive gear at points along the circumference of said first driven gear and said second driven gear respectively, is distributed so as to be reduced in magnitude.
~he invention will now be explained by exemplary embodiments as shown in the accompanying drawings, in which:
Fig. 1 is a schematic perspective view of a drive means according to the present invention, in which the two shafts rotate in opposite directions;
Fig. 2 is a schematic side view of the same drive means, in which one of the two extruding screws is also shown; and Fig. 3 is a schematic perspective view of another embodiment, in which the two shafts are caused to rotate in the same direction.
~ Referring first to Fig. 1, it will be seen that ; reference numerals 1 and 2 denote the two synchronized parallel counter-rotating shafts, which are arranged at a very close distance ~rom each other. Meshing gears 3 and 4 are mounted on shafts 1 and 2 respect-ively. According to the present invention, rotation is imparted to each of such gears 3 and 4 by means of at least two drive members. Two torques act upon gear ; 3 as provided by gears 6 and 7, which are located in suitable zones extending along the circumference of ~.~23~L~6 gear 3, to limlt the resulting thrust on ~ear 3. Gear4 is driven by two further clrive members terminating with gears 8 and 9, respectively. ~n the particular embodiment of Fig. ]., the drive members are gears driven by other gears 10, 11, 12 and 13~ respectively, which in turn are driven by independent motors.
This approach permits a reduction in the length of gears 3 and 4 since the latter, serving for synchroniza-tion of the two shafts, do not transmit the full power. Furthermore, good '~power division is obtained for the power supplied to each of the gears, as each torque is applied to the respective gear 3 or 4 at spaced apart peripheral zones so as to minimize stresses.
Referring now to Fig. 2, in which an extruder has been schematica].ly shown, it will be seen that the screws 15 have been formed on the shafts 1 and 2, although only one screw is shown in Fig. 2. The four gears 10, 11, 12 and 13 (of which only two are shown in Fig. 2) are connected to epicyclical reduction units 23 and 24, which are driven by motors 2~ and 26, respectively.
The shafts 1 and 2 must be supported by a series ~; of axial thrust bearings 16, which in turn are supported by a support 17. The axial strain caused by ; the extrusion pressure of the plastic material must be supported by a housing 18 containing the extruder screws 15. According to the invention, housing 18 and support 17 are directly connected to each other, for example by tie rods 19 and 20 which conveniently pass through hollow shafts 21 carrying the gears 6, 7, 8 and 9. Thus, the drive box 22, containing the gears 3 to 13, is relieved of any stress due to these considerable strains.
Referring to Fig. 3, it will be noted that the same reference numerals 1 and 2 are used to indicate two synchronized parallel shafts which rotate in the same direction and are arranged at a very close distance with respect to one another. Each of the `; ''~' ,.
:, .
' ~2~3L36 shafts has gears 3 and 4 mounted thereon, but not meshinq with each other. As in the embodiment of Fig.
1, each of sald gears 3 and 4 is caused to rotate by means of two drive members. Two torques are caused to act upon gear 3 by means of at least gear 6 and gear 7, which are arranged in suitable zones extending along the circumference of gear 3 to limit the resulting thrust on gear 3. Gear 4 is driven by two further drive members terminating with gears 8 and 9, respectively. As in Fig. 1, in this embodiment the drive members are gears driven by further gears 10, 11, 12 and 13, respectively, which in turn are driven by independent motors.
In this embodiment, synchronism between shafts 1 and 2 is provided by gear 30 meshing with gears 6 and 8 forming part of the drive members operating the two gears 3 and 4, respectively. Also in this case, the dimensions of gears 3 and 4 may be reduced, since gears
AND APPIICATION THEREOF TO A DO~BLE SC~EW EXTRUDER"
Thls invention relates to drive means capable of rotating two parallel adjacent shafts which are used, for example, in a double screw extruder for plastic materials.
In the case of two adjacent shafts rotating in opposite directions, the simplest way for rotating them is to transmit the entire torque of the motor only to one of the two shafts, and then impart a rotation to the second shaft by a pair of identical gears, each one - keyed to each shaft, such as to mesh with the other gear. On the other hand, if the parallel adjacent shafts must rotate in the same direction, the rotation imparted to the first shaft, by a single motor, is transmitted to the second shaft by means of an intermediate gear.
However, in these embodiments, the high speed of rotation of the shafts leads to severe wear and to very short life of the plasticizing screws. On the other hand a low speed would cause high torques and accordingly occasional hreakage. Further, when the distance between the shafts is very small, the gears must have very small pitch diameters.
In the last few vears, two ways have been developed to overcome this drawback.
The ~irst way consists of making shafts which are not parallel to one another but carry, for example, conical e~truding screws, so that at some distance from the cone apex the gears may have larger dimensions.
However, this complicates the entire construction.
A second approach is to separate the shaft actuation, by providing a reduction unit, in which each shaft directly receives from the reduction unit half of the total torque.
~ttempts were also made to increase the gear ; sturdiness by lengthening the latter or increasing their number. However, this also considerably adds to costs.
~A
, .......... .
. . ~ , . ~ .
:
: ~.
-; .
~Z~3~L36 There~ore, it is the object of an aspect of the present invention to provide a structurally economical solution to the problem of driving two closely spaced parallel adjacent shafts.
According to the present invention, the above object has been achieved by providing that two parallel shafts, each fitted with a gear meshing with further gears, are each driven by at least two drive members.
In a preferred embodiment the drive members are units which are completely independent of one another;
that is having fully distinct motors.
In this case, preferably, the use of epicyclical reduction units which are readily commercially available is contemplated.
In an application of the invention to a double screw extruder for plastic materials, it is preferable that the housing containing the extruding screws is directly connected to the support of the th-rust bearings, without overstressing the drive box. Preferably, the connection is obtained by means of tie rods passing through the drive box.
For two shafts rotating in the same direction, the two gears mounted on such shafts are slightly spaced - apart from each other, while the drive members are synch-ronized by an idler gear meshing therewith.
An aspect of the invention is as follows:
An apparatus rotationally driving two closely spaced parallel shafts, comprising: a first driven gear on a first of said shafts; a first drive gear and a se~ond drive gear, said first drive gear and said second drive gear being for directly driving said first dri~en gear; a first independent drive means for driving said first drive gear and a second independent drive means for driving said second drive gear; a second driven gear on a second of said shaft; a third drive gear and a fourth :
',~: ' ' ' ~23~3~
drive gear, said third drive gear and said fourth drive gear being for directly driving said second driven gear;
a third independent dr~ve means for drlving said third drive gear and a fourth independent drive means for driving said fourth drive gear; and synchronizing means for constraining each of said closely spaced parallel shafts to rotate at the same speed; whereby torque applied to said first driven gear by said first drive gear and by said second drive gear and to said second driven gear by said third drive gear and by said fourth drive gear at points along the circumference of said first driven gear and said second driven gear respectively, is distributed so as to be reduced in magnitude.
~he invention will now be explained by exemplary embodiments as shown in the accompanying drawings, in which:
Fig. 1 is a schematic perspective view of a drive means according to the present invention, in which the two shafts rotate in opposite directions;
Fig. 2 is a schematic side view of the same drive means, in which one of the two extruding screws is also shown; and Fig. 3 is a schematic perspective view of another embodiment, in which the two shafts are caused to rotate in the same direction.
~ Referring first to Fig. 1, it will be seen that ; reference numerals 1 and 2 denote the two synchronized parallel counter-rotating shafts, which are arranged at a very close distance ~rom each other. Meshing gears 3 and 4 are mounted on shafts 1 and 2 respect-ively. According to the present invention, rotation is imparted to each of such gears 3 and 4 by means of at least two drive members. Two torques act upon gear ; 3 as provided by gears 6 and 7, which are located in suitable zones extending along the circumference of ~.~23~L~6 gear 3, to limlt the resulting thrust on ~ear 3. Gear4 is driven by two further clrive members terminating with gears 8 and 9, respectively. ~n the particular embodiment of Fig. ]., the drive members are gears driven by other gears 10, 11, 12 and 13~ respectively, which in turn are driven by independent motors.
This approach permits a reduction in the length of gears 3 and 4 since the latter, serving for synchroniza-tion of the two shafts, do not transmit the full power. Furthermore, good '~power division is obtained for the power supplied to each of the gears, as each torque is applied to the respective gear 3 or 4 at spaced apart peripheral zones so as to minimize stresses.
Referring now to Fig. 2, in which an extruder has been schematica].ly shown, it will be seen that the screws 15 have been formed on the shafts 1 and 2, although only one screw is shown in Fig. 2. The four gears 10, 11, 12 and 13 (of which only two are shown in Fig. 2) are connected to epicyclical reduction units 23 and 24, which are driven by motors 2~ and 26, respectively.
The shafts 1 and 2 must be supported by a series ~; of axial thrust bearings 16, which in turn are supported by a support 17. The axial strain caused by ; the extrusion pressure of the plastic material must be supported by a housing 18 containing the extruder screws 15. According to the invention, housing 18 and support 17 are directly connected to each other, for example by tie rods 19 and 20 which conveniently pass through hollow shafts 21 carrying the gears 6, 7, 8 and 9. Thus, the drive box 22, containing the gears 3 to 13, is relieved of any stress due to these considerable strains.
Referring to Fig. 3, it will be noted that the same reference numerals 1 and 2 are used to indicate two synchronized parallel shafts which rotate in the same direction and are arranged at a very close distance with respect to one another. Each of the `; ''~' ,.
:, .
' ~2~3L36 shafts has gears 3 and 4 mounted thereon, but not meshinq with each other. As in the embodiment of Fig.
1, each of sald gears 3 and 4 is caused to rotate by means of two drive members. Two torques are caused to act upon gear 3 by means of at least gear 6 and gear 7, which are arranged in suitable zones extending along the circumference of gear 3 to limit the resulting thrust on gear 3. Gear 4 is driven by two further drive members terminating with gears 8 and 9, respectively. As in Fig. 1, in this embodiment the drive members are gears driven by further gears 10, 11, 12 and 13, respectively, which in turn are driven by independent motors.
In this embodiment, synchronism between shafts 1 and 2 is provided by gear 30 meshing with gears 6 and 8 forming part of the drive members operating the two gears 3 and 4, respectively. Also in this case, the dimensions of gears 3 and 4 may be reduced, since gears
3 and 4 serve only to transmit the portion of the power assigned thereto.
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Claims (5)
1. An apparatus rotationally driving two closely spaced parallel shafts, comprising:
a first driven gear on a first of said shafts;
a first drive gear and a second drive gear, said first drive gear and said second drive gear being for directly driving said first driven gear;
a first independent drive means for driving said first drive gear and a second independent drive means for driving said second drive gear;
a second driven gear on a second of said shaft;
a third drive gear and a fourth drive gear, said third drive gear and said fourth drive gear being for directly driving said second driven gear;
a third independent drive means for driving said third drive gear and a fourth independent drive means for driving said fourth drive gear; and synchronizing means for constraining each of said closely spaced parallel shafts to rotate at the same speed;
whereby torque applied to said first driven gear by said first drive gear and by said second drive gear and to said second driven gear by said third drive gear and by said fourth drive gear at points along the circumference of said first driven gear and said second driven gear respectively, is distributed so as to be reduced in magnitude.
a first driven gear on a first of said shafts;
a first drive gear and a second drive gear, said first drive gear and said second drive gear being for directly driving said first driven gear;
a first independent drive means for driving said first drive gear and a second independent drive means for driving said second drive gear;
a second driven gear on a second of said shaft;
a third drive gear and a fourth drive gear, said third drive gear and said fourth drive gear being for directly driving said second driven gear;
a third independent drive means for driving said third drive gear and a fourth independent drive means for driving said fourth drive gear; and synchronizing means for constraining each of said closely spaced parallel shafts to rotate at the same speed;
whereby torque applied to said first driven gear by said first drive gear and by said second drive gear and to said second driven gear by said third drive gear and by said fourth drive gear at points along the circumference of said first driven gear and said second driven gear respectively, is distributed so as to be reduced in magnitude.
2. The apparatus of claim 1, wherein said synchronizing means includes means for constraining said shafts to rotate in opposite directions.
3. The apparatus of claim 1, wherein said synchronizing means comprises interengaging teeth of said driven gears.
4. The apparatus of claim 1, wherein said synchronizing means includes means for constraining said shafts to both rotate in one direction.
5. The apparatus of claim 1, wherein said drive means each include a terminating gear for driving said respective drive gears and said synchronizing means comprises an idler gear, said idler gear engaging one terminating gear of one drive means of each driven gear.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000450420A CA1223136A (en) | 1984-03-23 | 1984-03-23 | High torque drive means for two very close shafts and application thereof to a double screw extruder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000450420A CA1223136A (en) | 1984-03-23 | 1984-03-23 | High torque drive means for two very close shafts and application thereof to a double screw extruder |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1223136A true CA1223136A (en) | 1987-06-23 |
Family
ID=4127496
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000450420A Expired CA1223136A (en) | 1984-03-23 | 1984-03-23 | High torque drive means for two very close shafts and application thereof to a double screw extruder |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1223136A (en) |
-
1984
- 1984-03-23 CA CA000450420A patent/CA1223136A/en not_active Expired
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |