JPH0661824B2 - Double screw extruder - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a drive means capable of driving a set of shafts with two shafts arranged in parallel or converging at a distance close to each other. Is subject to strong axial pressure. These shafts are used, for example, in double-screw extruders for plastic materials.

BACKGROUND OF THE INVENTION When two closely spaced shafts move in opposite directions,
The simplest way to rotate them is to transfer the torque of the motor to only one of its two shafts.
Giving rotation to a second shaft by a pair of identical gears, each of which is keyed to each of the two shafts for meshing with the other gear. On the other hand, when the shafts rotate in the same direction, the rotation normally imparted to the first shaft by a single motor is transmitted to the second shaft by the intermediate gear.

However, in these embodiments, the high speed rotation of the shaft causes severe wear of the plasticizing screw, greatly shortening its life. On the other hand, low speeds will result in high torque, resulting in occasional damage. Furthermore, if the shaft distances are very small, the gears must have a very small pitch diameter.

In the last few years, two approaches have been tried to overcome this drawback.

The first method consists of forming a shaft with a conical extrusion screw, which allows the gear to have a larger dimension at a distance from the apex of the cone. However, this complicates the overall configuration.

A second attempt is to isolate the drive of the shafts by providing a reducer with two outlets, each of which outlets is at the free end of each shaft,
That is, movement is given to the end opposite to the end having the screw. The disadvantage of this system is that the two very close shafts that are subject to a strong torsion are very long. That is to leave the required space along their axis for the housing of the thrust bearing. Usually, each thrust bearing of the shaft is displaced relative to the other thrust bearing. Therefore, this solution is still inadequate. This is because shafts that resist torsional stress must increase their diameter.

Attempts have also been made to increase gear strength by increasing the length or number of gears. However, this also results in a considerable cost increase.

The object of the present invention is therefore to provide an economical structural solution to the problem of driving two parallel or converging shafts which are arranged in close proximity to one another and are subjected to strong axial pressure.

According to the invention, the above object is achieved in that two parallel or converging shafts each provided with a gear meshing with another gear are each driven by at least two drive members acting around said respective gear. It is achieved by being done.

In the preferred solution, the drive members are actuated by a unit which has motors which are completely independent of each other and wholly separate.

In this case, it is preferable to use a commercially available planetary gear speed reduction unit.

In the application of the drive to a double screw extruder for plastic materials, the housing containing the extrusion screw is preferably directly connected to the support of the thrust bearing without over-pressing the drive box. Said connection is preferably obtained by means of a joining rod passing through said drive box.

Due to the rotation of the two shafts rotating in the same direction, the two gears mounted on such shafts are slightly separated from each other, while the drive member is synchronized by the idle gear meshing therewith.

If the shafts converge, it is possible to do with all the conical gears of the drive member that mesh with each of the conical gears of each shaft. It is also possible to provide each shaft with two cylindrical gears that do not mesh with each other. The two gears are driven by at least two drive members that terminate in cylindrical gears that mesh with the respective cylindrical gears.

It should be noted that the present invention is described by way of example embodiments as shown in the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION First of all, referring to FIG. 1, reference numerals 1 and 2 designate two parallel shafts which rotate in reverse in synchronization with each other, which are arranged very close to each other. You can see that. Gears 3 and 4 that mesh with each other are mounted on each shaft. According to the invention, the rotation of those gears 3 and 4 is each provided by at least two drive members. Two torques act on the gear 3 by means of the gears 6 and 7, which gears 6 and 7 are arranged in suitable areas on the circumference of the gear 3 in order to limit the axial pressure exerted on the gear 3. Gear 4
Are driven by two further drive members terminating in gears 8 and 9, respectively. In the particular embodiment of FIG. 1, the drive members are gears driven by other gears 10, 11, 12 and 13 each driven by an independent motor.

This solution makes it possible to reduce the length dimension of the gears 3 and 4. Because the latter, which only works for the synchronization of its two shafts, does not transfer all the power. Moreover, a good power division is obtained with respect to the power applied to each of those gears. This is because each torque is applied to the respective gear 3 or 4 in the surrounding area that is spaced to minimize stress.

With reference to FIG. 2 in which the extrusion device is schematically shown, it can be seen that only one screw is shown in FIG. 2 but the shafts 1 and 2 are provided with a screw 15. Will. Four gears 10, 11, 1
2, 2 and 13 (only two of which are shown in FIG. 2) are coupled to planetary gear reducers 23 and 24 driven by motors 25 and 26, respectively.

Shafts 1 and 2 are supported by a series of axial thrust bearings 16, the strain of which is supported by supports 17. The axial strain caused by the extrusion pressure of the plastic material is supported by the housing 18 containing the extrusion screw 15. According to the invention, the housing 18 and the support 17 are directly connected to each other, which is, for example, a hollow shaft 2 supporting the gears 6, 7, 8 and 9.
This is done by connecting rods 19 and 20 conveniently penetrated through 1. The drive box 22 containing the gears 3 to 13 is thus free from any stress due to these considerable strains.

With reference to FIG. 3, the same reference numbers 1 and 2 are used to indicate two synchronized parallel shafts which rotate in the same direction and are arranged at very close distances. You will understand. Gears 3 and 4 are mounted on each of the shafts, respectively, but the gears do not mesh with each other. As in the embodiment of FIG.
The movements of said gears 3 and 4 are each provided by at least two drive means. Two torques are exerted on the gear 3 by the gears 6 and 7 and their gears 6 and 7
Are arranged in suitable areas around the gear 3 in order to limit the axial forces exerted on said gear 3. Gear 4 is driven by two other drive members terminating in gears 8 and 9, respectively. Also in this case, those driving members are gears driven by the other gears 10, 11, 12 and 13 and are sequentially driven by independent motors.

In this case, the synchronization between the shafts 1 and 2 is 2 respectively.
Provided by a gear 30 meshing with gears 6 and 8 forming part of the drive member for operating one gear 3 and 4.
Also in this case, the dimensions of the gears 3 and 4 are greatly reduced.
Because those gears act only to transfer the split power given to them.

FIG. 4 shows two converging shafts 31 and 32 on which conical gears 33 and 34 are mounted in mesh with each other. Two drive members act on each of them, due to the conical gears 36, 37, 38, 39.

FIG. 5 shows another embodiment in which the converging shafts 31 and 32 are provided with cylindrical gears 43 and 44 which do not mesh with each other and which mesh for synchronization. The gears 35 and 45 are provided. Gears 43 and 44 are each driven by two drive members, which drive members are their final gears 46,4.
It operates by 7, 48, 40. In this case, all the driving means can be implemented by cylindrical gears.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a drive means according to the invention, the two shafts of which rotate in opposite directions. FIG. 2 is a schematic side view of the same drive means, also one of the two extrusion screws being shown. FIG. 3 is a schematic perspective view of another embodiment, part 2 thereof.
The two shafts are rotated in the same direction. 4 and 5 are schematic perspective views of two further embodiments, which relate to a converging shaft. In the figure, 1 and 2 are shafts, 3 and 4 are gears attached to each shaft, 6, 7, 8, and 9 are drive members, 10, 11, 12, and 13 are driven by independent motors. A gear, 15 an extrusion screw, 16 a thrust bearing, 17 a support, 18 a housing, 19 and 20 a connecting rod, 21 a hollow shaft, 22 a drive box, 23 and 24 a planetary gear reducer, 25 and 26
Is a motor, 30 is a synchronizing gear, 31 and 32 are converging shafts, 33 and 34 are conical gears on converging shafts, 36, 37, 38 and 39 are conical gears of drive members, gears 43 And 44 are cylindrical gears on the converging shaft, 35 and 34 are synchronizing gears, 46, 47, 48,
Reference numeral 40 denotes a cylindrical gear of the driving member. In each figure, the same reference numerals indicate the same contents or corresponding portions.

Claims (6)

[Claims] 1. A double-screw extruder comprising two closely-closed shafts (1, 2 ,; 31, 32) of a double-screw and a device for rotationally driving the two closely-closed shafts. A drive gear (3,4; 43,4) on each of said shafts.
4), synchronization means for constraining the two shafts in close proximity so as to rotate at the same speed in either one of the same direction and the opposite direction, and a plurality of drive means for driving the two shafts. And (a) the drive means includes at least four independent drive units (25, 26), (b) each of the driven gears (3, 4; 43, 44) is at least the drive unit. And (c) each of the driven gears (3, 4; 43, 44) is driven independently by a corresponding drive unit (6-9; 36-39). ) A double screw extruder. 2. The planetary reduction unit (2)
3, 24) is included.
The double-screw extruder according to the item. 3. The twin-screw extruder according to claim 1, wherein the synchronizing means includes the same driven gears that engage with each other. 4. A drive gear of one drive unit for operating a driven gear is engaged with one idle gear, and the idle gear is also engaged with a drive gear of a drive unit for operating another driven gear. The double screw extrusion apparatus according to claim 1, wherein 5. The twin-screw extruder according to claim 1, wherein the two adjacent shafts are parallel to each other. 6. The two shafts according to claim 1, wherein the two shafts adjacent to each other are closer to each other in the front direction, and the driven gear on each of the shafts is a bevel gear. Heavy screw extruder.