JPH0694045A - Screw shaft coupling of extruder, etc. - Google Patents

Abstract

PURPOSE:To aim at the easing of working accuracy, simplification in structure, the facilitation of assembly and a reduction in cost by securing an overload protection function in a shaft coupling. CONSTITUTION:This is a shaft coupling which connects a screw shaft 1 and a transmission shaft 8 via a cylindrical coupling 10, and a joint part 2 of the screw shaft 1 and this coupling 10 are joined by means of spline connection, while a joint part 9 of the transmission shaft 8 is formed into being spline (or key)-less, and a fitting part 14 of the coupling 10 is formed a spline (or key)-less transmission surface. In succession, a ring slit 13, where a pressure fluid is pressed in, is formed in a coupling inner part of the fitting part 14, and a fluid is fed to the inner part of a slit 13, whereby an inner circumferential side of this slit 13 is bulged toward a shaft center or diametrally contacted otherwise, tightening a peripheral surface of the joint part 9 uniformly to lock it tight, and thereby torque transmission by means of frictional transmission is made achievable, and at the time of slip occurrence due to overloading, a shear tube 21 is provided which spouts a fluid in the ring slit 13, whereby depressurization takes place instantly and automatically for torque interruption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw shaft joint in a machine for processing plastics, for example, a twin-screw extruder for kneading granulation and molding, as well as various extruders, injection molding machines, screw type feeders and the like. It is a thing.

[0002]

2. Description of the Related Art Generally, a twin-screw kneading extruder for processing plastics has a drive motor 31, a speed reducer 32, a transmission gear unit 33, and a junction box 3 as shown in FIG.
4, barrel assembly 35, screw assembly 36
(See FIG. 7), a shaping die head 37 and the like, a transmission gear unit 33 is provided with a biaxial distribution gear, a thrust bearing and the like, which are not shown, and a screw shaft joint 38 is provided in the junction box 34. Is provided.

As shown in FIG. 7, the barrel assembly 35 is assembled in a long manner by connecting a number of short sections having eyeglass-shaped through holes 39 in the longitudinal direction, and a pair of two screw assemblies 36 are rotated inside. The screws are freely incorporated, and the screws mesh with each other to rotate in the same direction (or different directions). Conventionally, as shown in FIGS. 6 and 7, a spline 41 is formed at the joint portion of the screw shaft 40, and a spline 43 is also formed at the end of the output shaft 42 (transmission shaft) of the transmission gear unit 33 to form a cylindrical shape. The inner circumference of the coupling 44 is splined over the entire length to form a spline shaft hole 45.
The splines 41 and 43 of both shafts 40 and 42 are inserted into the shaft 45 from both sides, and torque is transmitted to the screw shaft 40 by the spline joint.

Then, in order to restrict the movement of the screw shaft 40 in the longitudinal direction and fix the position, the coupling 46 is tightened and fixed by a ring 46 and a nut 47 at both ends. In addition, it is necessary to exactly match the phase in the axial direction together with the phase in the rotational direction of the screw shaft 40.
An adjustment plate 48 is fitted between 0 and 42, and the thickness is adjusted on site.

In a plastic extruder, an excessive torque may be generated on the load side due to raw materials, operating conditions, and some kind of abnormality (due to a control state, inclusion of foreign matter, etc.), or a sudden peak load or a sticking stop may occur. However, there is a need for overload protection measures, but the actual situation is that no measures have been taken, except when the user's requirements and severe usage conditions are expected.

On the other hand, in the twin-screw extruder,
Due to the physical properties of the product and the conditions under which it is used, there are severe restrictions on mechanical strength. In particular, the distance between the two screw shafts is very narrow, so the diameters of the screw shaft and shaft joint are inevitable. It becomes smaller and becomes a neck on strength. As the overload protection means of the twin-screw extruder, the motor is stopped by detecting the overload current, and the mechanical torque is limited (a slip clutch is provided in the middle of the drive system, and when the torque is exceeded, the torque is slipped to the set torque or less). ,
Mechanical torque shut-off (1 Shear pin on drive system coupling or V pulley, or 2 ball system on drive system)
(A pocket type torque transmission mechanism is provided).

[0007]

By the way, in the above-mentioned prior art, in order to accurately match and hold the two-shaft meshing phase of the screw assembly, the spline of the shaft joint portion must be exactly matched. However, there is a problem that high processing accuracy is required. Further, since all the conventional overload protection means are installed in the transmission system together with the coupling or the V pulley between the motor and the gear box, even if the torque is instantaneously cut off, the torque release portion and the screw shaft contact are not formed. The inertial energy of the whole rotating body must be absorbed by the screw shaft. Therefore, in the case of sudden overload or stoppage of load fixation, shock absorbing torque of rotational energy is generated together with the driving torque of the motor. Therefore, there is a problem that sufficient overload protection is difficult.

Therefore, it is conceivable to provide the torque release at the screw shaft joint portion which is as close to the load as possible, but the distance between the two shafts is narrow and there is no mounting space, and the allowable value of the overhang load of the shaft portion is very small and the weight is heavy. Since it is not possible to attach an object, it is the position where the motor output shaft torque is most decelerated and the transmission torque becomes maximum, so
The conventional overload protection means requires a very large size. Furthermore, when the screw assembly is attached and detached, it is necessary to quickly disassemble and assemble the screw shaft joint part in a narrow space. There are many problems such as not being possible.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to protect a machine most effectively under severe operating conditions of an extruder or the like. With a load protection function, the structure is simple, processing accuracy can be relaxed, disassembling and assembling in the junction box is easy, and assembly accuracy is easy to secure. To provide.

[0010]

In order to achieve the above object, the present invention takes the following technical means. That is, according to the present invention, in a shaft joint that connects a screw shaft and its transmission or drive shaft via a tubular coupling, at least one of both shaft ends to be connected is a spline or keyless joint portion. At the same time, the fitting portion of the coupling fitted to the joint portion is a transmission surface without splines or keys, and an annular slit into which a pressurized fluid is pressed is formed inside the coupling of the fitting portion. By supplying fluid into the slit, the inner peripheral side of the annular slit bulges and contracts toward the axis, and the outer peripheral surface of the splineless joint is evenly tightened and fixed, and torque transmission by friction transmission is performed. It is characterized by making it possible.

Further, the present invention is characterized in that a depressurizing means for automatically discharging the pressurized fluid in the annular slit when the friction transmission surface is slipped due to overload torque is provided.

[0012]

According to the present invention, when a pressurized fluid is supplied into the annular slit of the coupling, the screw shaft and the drive system transmission shaft are connected by friction transmission via the coupling,
Torque is transmitted. When a slip (overload) occurs between the splineless joint and the fitting of the coupling, the depressurizing means operates to eject the pressurized fluid in the annular slit and instantly depressurize. Therefore, the friction transmission is released, the torque transmission is completely cut off, and overload protection at the optimum position becomes possible.

Further, in assembling the screw shaft joint, the screw shaft side joint part is inserted into the fitting part of the coupling, and the coupling and the joint part are fixed, whereby the screw shaft joint can be easily assembled. At this time, by releasing the tightening fixation of the splineless joint part and the fitting part of the coupling, it is only necessary to match the screw meshing phase of the screw shaft, and the joint part can be fixed at any optimum position. Can be performed accurately and easily.

Further, the disassembly of the screw shaft joint can be easily carried out by releasing the fixation of the joint part of the screw shaft and the coupling and pulling out the screw shaft. When the joint portion of the screw shaft is splineless, the screw shaft may be pulled out after discharging the fluid in the annular slit of the fitting portion of the coupling to release the pressure.

[0015]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a first embodiment of the present invention, the basic construction of the extruder is the same as that shown in FIG.
Only the book is shown, but it is the same as the conventional example, and the joint part 2
Has a spline formed therein, a locking circumferential groove 3 formed therein, a threaded hole 4 formed in an end surface thereof, and an adjusting ring 5 mounted by a screw 6.

The adjusting ring 5 is for adjusting the shaft end position of the screw shaft 1 and for transmitting and absorbing axial force, that is, thrust, due to the resin pressure at the screw tip to the gear box 7, and at the time of torque release. The thrust transmitting surfaces in the above are provided for mutual rotation. Reference numeral 8 denotes a transmission shaft (output shaft of a transmission gear unit), which is supported by the gear box 7 and has a joint 9 protruding from the gear box 7. The joint 9 is a splineless (or keyless) shaft portion. The diameter of the tip is reduced to form the bearing fitting portion 9A.

Reference numeral 10 denotes a coupling, which has a cylindrical shape, one inner peripheral surface of which is formed as a spline shaft hole 11, and the other splineless fitting portion is provided with an annular slit 13, and the fitting portion 14 is formed. Bearings 15 and 16 are fitted to the inner and outer ends of the joint portion 9 and the bearing fitting portion 9A, respectively.
And the bearings 15 and 16, and the outer peripheral surface of the joint portion 9 and the expansion / contraction inner peripheral surface 12 of the fitting portion 14 of the coupling 10 are relatively rotatable.

Also, the spline shaft hole 11 of the coupling 10
A male screw portion 17 is formed on the outer periphery of the side end, and a fixing nut 18 is screw-fitted therein, and a pressurized fluid supply hole 19 communicating with the annular slit 13 and a peripheral surface of the coupling portion 10 on the fitting portion 14 side are provided. A shear tube fitting hole 20 is provided, and a shear tube 21 (see FIG. 2) as a depressurizing means is fitted in the fitting hole 20. A shear lug 25 is fixed to the transmission shaft 8 and the tip of the shear tube 21 is cut to form an annular slit.
The fluid in 13 is discharged to release the pressure.

Reference numeral 22 denotes a thrust receiving plate which is fitted between the adjusting ring 5 and the bearing 15 so that the thrust of the screw shaft 1 is transmitted from the adjusting ring 5 through the bearing 15 to the end face of the joint 9 of the transmission shaft 8. It has become. The receiving plate 22 can be formed integrally with the adjusting ring 5 and made of a material containing a solid lubricant. 23 is a lock ring divided into two parts. When assembling the shaft joint, the lock ring is externally fitted into the lock circumferential groove 3 of the screw shaft 1, and the fixing nut 18 is screwed in to press the side surface of the lock ring 23. Adjusting ring on the end face of screw shaft 1 joint 2
5 through the thrust receiving plate 22 and the thrust receiving plate 22 to the final position where it abuts on the bearing 15, and by fixing the screw shaft 1
The joint portion 2 and the coupling 10 are connected and fixed like relative rotation and axial movement.

The outer peripheral surface of the joint portion 9 of the transmission shaft 8 is
It is a friction transmission surface, and the optimum material is selected and surface treatment is applied to prevent seizure during slippage.
Then, a groove 24 for fine lubrication is formed on the expansion / contraction inner peripheral surface 12 of the coupling 10, and a lubricant is filled in the groove 24 to prevent wear during slip and idling. It is possible to deal with it more effectively.

The metal fitting 19 '(details omitted) connected to the pressurized fluid supply hole 19 has a check valve for preventing backflow so as to prevent the pressurized fluid from leaking. In the first embodiment, the coupling 10 is attached to the joint portion 9 of the transmission shaft 8 via the bearings 15 and 16, and supplies a pressurized fluid (for example, pressure oil) into the annular slit 13 to cause a predetermined pressure abnormality. Unless otherwise, since there is a minute gap between the outer peripheral surface of the joint portion 9 and the (expanding / contracting inner peripheral surface of the coupling 10), there is no power transmission and they can rotate relative to each other.

Therefore, when connecting the screw shaft 1 to the transmission shaft 8, first, the fixing nut 18 is externally fitted to the screw shaft 1 so as to be positioned on the tip side of the circumferential groove 3, and the spline joint portion is provided.
2 After adjusting the axial phase of the screw assembly of the two screw shafts 1 with the adjusting ring 5 at the end,
The joint portion 2 is inserted into the spline shaft hole 11 of the coupling 10, the split locking ring 23 is externally fitted to the locking circumferential groove 3, and the inlet side expanded portion 11A of the shaft hole 11 is fitted. Screw the nut 18 into the external thread 17 of the coupling 10, push the screw shaft 1 toward the transmission shaft 8 via the side surface of the ring 23, and bring the adjusting ring 5 into contact with the thrust receiving plate 22. This completes the connection assembly.

Therefore, the annular slit 13 of the coupling 10
When a pressurized fluid is supplied to the inside and the pressure exceeds a predetermined pressure, the expansion / contraction inner peripheral surface 12 expands and contracts in diameter toward the axial center, uniformly tightens the joint portion 9 of the transmission shaft 8, and transmits the friction force. Axial fixation is performed. At this time, since the frictional force of the fitting portion 14 changes according to the fluid pressure to be supplied, it can be set to an arbitrary transmission torque by adjusting the discharge pressure of the fluid supply pump (manual or electric). it can.

During power transmission, the load side (screw shaft 1
Side) torque exceeds the set value, the joint part 9 and the mating part 14
Although slippage occurs on the transmission surface of, and overload is prevented,
At this time, the tip of the shear tube 21 is cut by the shear lug 25 that rotates together with the transmission shaft 8, the fluid in the annular slit 13 is ejected and depressurized, and a minute gap is generated between the joint portion 9 and the fitting portion 14. Occurs, the transmission torque is instantaneously cut off, and only the transmission shaft 8 idles.

The joint between the coupling 10 and the transmission shaft 8
Since the bearings 15 and 16 are fitted between the 9 and 9,
Since the concentricity of the joint portion 9 is maintained, idling after the torque release is smoothly performed without any trouble, and seizure does not occur. Then, after the operation is stopped, the shear tube 21 is replaced, the shear lug 25 is engaged, the pressurized fluid is supplied into the annular slit 13, and the coupling portion 9 between the coupling 10 and the transmission shaft 8 is connected.
The operation can be restarted by tightening and fixing so that the power can be transmitted.

When the shaft joint is disassembled when the screw shaft 1 is pulled out or replaced, after tightening the fixing nut 18 to remove it from the male thread 17 of the coupling 10, the screw shaft 1
By pulling out 1 in the material extruding direction, the spline joint portion 2 comes out of the shaft hole 11 and can be easily disassembled. FIG. 3 shows the essential parts of the second embodiment of the present invention, and
The difference from the embodiment is that the friction transmission portion of the coupling 26
This is a point where the above is separately attached to the coupling 10 (about press-fitting), and an effect equivalent to that of the first embodiment can be expected. In the second embodiment, since the torque release portion in which the annular slit is swollen is a separate body, its processing is facilitated, and the optimum material can be selected and used as necessary.

FIG. 4 shows a third embodiment of the present invention.
The difference from the first embodiment is the joint of the screw shaft 1.
2 is spline (or keyless) and coupling 10
The fitting portion 27 of is also formed by the expansion / contraction inner peripheral surface 28 and the annular slit 29 is formed, and the pressurized fluid supply hole 30 and the supply metal fitting 30 ′ communicating with the guide slit 29 are provided to supply the fluid into the annular slit 29. The point is that the expansion / contraction inner peripheral surface 28 is expanded / contracted by pressure to transmit and release the torque.

Incidentally, the screw shaft 1 in the third embodiment
Although the coupling fitting portion 27 fitted to the joint portion 2 of is a splineless joint with a simple friction transmission surface,
A shear tube attachment hole communicating with the annular slit 29 can be provided and a shear tube can be attached to provide a torque release function. According to the third embodiment, the same effect as that of the first embodiment can be expected, and since the spline processing is unnecessary, the manufacturing cost can be reduced.

In the above embodiments, ball bearings are used as the bearings 15 and 16, but needle bearings, oil-impregnated bushes, and other optimum bearings can be used according to the design conditions. Further, in each of the embodiments, at the same time when the instantaneous torque cutoff operation due to the overload torque is performed, the decrease or stop of the rotation speed of the screw shaft 1 (load side) is detected, and the drive motor is stopped as soon as possible. As a result, contact wear of each member due to continuous idling in the fitting portion 14 of the joint portion 9 after depressurization in the annular slit 13 is further reduced, and the adjusting ring 5 at the end of the screw shaft 1 is also reduced. It is possible to reduce sliding wear of the bearings 15 and 16, and to improve the durability of the entire shaft joint including the lives of the bearings 15 and 16 and maintain accuracy.

The present invention is not limited to each of the above-mentioned embodiments, but in a twin-screw extruder, a plasticizer for an end-screw extruder, a kneader, an injection molding machine and a hollow molding machine, and various screw type feeders. It can be used for screw shaft joints, and applicable materials include various synthetic resins, rubber and their composites, ceramics such as plastic ceramic materials and plastic fine ceramics, powder metallurgy materials, foods (soybean, corn, wheat, rice, rice cake, fish, etc.). Processing of surimi, dehydration of various materials, drying, etc.) and the like.

[0031]

As described above, according to the present invention, in a shaft coupling which connects a screw shaft and its transmission or drive shaft via a tubular coupling, at least one of both shaft ends to be connected is a spline or The fitting part of the coupling that is fitted to the fitting part is a spline or a keyless transmission surface, and a pressurized fluid is press-fitted into the coupling of the fitting part. An annular slit is formed, and by supplying a fluid into the slit, the inner peripheral side of the annular slit bulges and contracts toward the axial center to uniformly tighten the outer peripheral surface of the spline-less joint portion. Since it is fixed and enables torque transmission by friction transmission, it is most effective because slippage occurs in the shaft joint when overload occurs under severe operating conditions such as extruders. In machine Protection can be achieved, processing accuracy can be eased, assembly and disassembly can be facilitated and accuracy can be secured, and cost reduction due to omission or reduction of spline processing, etc. can be achieved, and it is not necessary to separately provide a torque releaser. Therefore, the structure is simple and compact, and the transmission torque can be changed accurately and greatly by adjusting the pressure of the pressurized fluid.

Further, the present invention is characterized in that it is provided with depressurizing means for automatically discharging the fluid under pressure in the annular slit when slippage occurs, so that the joint portion and its contact portion due to overloading are provided. When slippage occurs on the transmission surface of the fitting portion, depressurization in the annular slit is instantaneously performed, torque transmission to the load side is completely cut off, and the overload protection of the machine can be most effectively achieved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is an enlarged view of part A in FIG.

FIG. 3 is a vertical sectional view showing a main part of a second embodiment of the present invention.

FIG. 4 is a vertical sectional view showing a third embodiment of the present invention.

FIG. 5 is an overall front view of a twin-screw kneading extruder.

FIG. 6 is a partially cutaway plan view showing an example of a conventional screw shaft joint.

7 is a partially cutaway front view of FIG.

[Explanation of symbols]

 1 Screw shaft 2 Joint part 8 Transmission shaft 9 Joint part 10 Coupling 13 Annular slit 14 Fitting part 21 Shear tube (decompression means) 25 Shear lug (decompression means) 27 Fitting part 29 Annular slit

Claims (2)

[Claims] 1. A shaft joint for connecting a screw shaft and its transmission or drive shaft via a tubular coupling, wherein at least one of both shaft ends to be connected is a spline or keyless joint portion. , The fitting part of the coupling fitted to the joint part is a transmission surface without splines or keys, and an annular slit into which the inside of the coupling of the fitting part is press-fitted is formed, and a fluid is supplied into the slit. By doing so, the inner peripheral side of the annular slit bulges and contracts toward the axial center, and the outer peripheral surface of the joint portion without splines is uniformly tightened and fixed, enabling torque transmission by friction transmission. Characteristic screw shaft joints for extruders, etc. 2. A screw shaft joint for an extruder or the like according to claim 1, further comprising depressurizing means for automatically discharging the pressurized fluid in the annular slit when slippage occurs.