JP2531784B2 - Electric injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention provides a screw housed in a heating cylinder through a rotary motion transmitting means and a straight motion transmitting means in order to impart rotary motion and linear motion to the screw. The present invention relates to an electric injection device configured to transmit power by an electric motor.

(Prior Art) Conventionally, in an injection molding method in which a molding material such as plastic is injected into a molding die to manufacture a molded article, a hydraulic type and an electric type injection device are mainly used. .

The basic problem when molding using such an injection device is that the injection device generally arranges its screw along the horizontal axis, and in this arrangement, the screw is rotated, Further, it is a point that the installation area becomes very large due to a structural relationship such as a driving operation and a control means, which are associated with a straight movement. In particular, in a factory where work processes such as assembling work are linked to a molded product, it is necessary to devise a mounting area as small as possible.

(Problems to be Solved by the Invention) Therefore, it has been proposed that the injection apparatus be vertical and the floor projection area of the apparatus be as small as possible to ease the installation conditions of the injection apparatus in the factory. However, the hydraulic injection device requires peripheral devices such as a hydraulic pump and piping equipment, which alone has a drawback that the occupied floor area is large.
In addition, there is a risk that the environment will be contaminated with oil mist generated from hydraulically driven equipment, and it is unsuitable as a peripheral equipment of a molding machine that needs to maintain a clean molding environment.

On the other hand, in the conventional electric injection device, since the installation area is not taken into consideration in advance, the structure and arrangement of the means for imparting the rotation operation and the rectilinear operation of the screw on the proximal end side of the screw are unsuitable. However, even if the configuration and arrangement are maintained vertically, the effect of sufficiently reducing the floor projection area cannot be obtained.

The present invention has been made based on the above-mentioned circumstances, and rotational movements and rectilinear movements related to a screw, further, each component such as a back pressure imparting means capable of handling a back and forth in accordance with the injection amount, of the screw. An object of the present invention is to provide an electric injection device that is arranged in series in the axial direction and has a vertical structure so that the floor projection area can be made as small as possible.

(Means for Achieving the Object) In order to achieve the above object, in the electric injection device of the present invention, a heating cylinder vertically arranged with an injection port for injecting a molding material facing downward, and the inside of the heating cylinder. A screw housed in, a vertically arranged spline shaft connected to the upper end of the screw, a ball screw coaxially provided on a guide shaft continuous to the upper end of the spline shaft, and a ball nut screwed to the ball screw. Corresponding to the upper end of the ball screw, a cylinder rod that operates under the control of compressed fluid in a back pressure cylinder to apply a back pressure to the guide shaft, and the spline shaft and the ball nut are provided. , A structure in which power is transmitted from an electric motor via a rotary motion transmitting means for giving a rotary motion and a linear motion transmitting means for giving a straight motion In addition, the detection sensor that detects the process path length in the screw moving process during suck back is arranged corresponding to the moving region of the ball screw so that the position can be set according to the amount of injection molding material. And

(Operation) In the above configuration, most of the components are arranged in tandem along the axis of the screw, and the electric motor also
The rotary motion transmission means and the rectilinear motion transmission means are commonly used, and hence the floor projection area can be reduced. Moreover, the process path length at the time of suck back can be easily determined by setting the position of the detection sensor, and it is possible to cope with the adjustment of the suck back amount according to the amount of the injection molding material.

(Embodiment) FIG. 1 (a) is a schematic sectional view of an electric injection apparatus according to this embodiment, and FIG. 1 (b) is II-II in FIG. 1 (a).
A sectional view, FIG. 1 (c) is III-III in FIG. 1 (a).
FIG. 2 is a sectional view, and FIG. 2 is a rotation mechanism, a rectilinear mechanism,
A back pressure mechanism, a perspective view around the clutch and the electric motor, the third
(A)-(e) are operation | movement explanatory drawings of a present Example, FIG. 4 is a flowchart of the injection molding by the apparatus of a present Example.

As shown in FIGS. 1 and 2, the electric injection device of the present embodiment includes a screw 2 housed in a superheated cylinder 1, a spline shaft 3 fixed to the screw 2 by a pin 4, and a spline shaft. 3, a hollow ball screw guide shaft 5 connected to an upper end of a stopper plate 7 by a bolt or the like (not shown), a hollow ball screw 6 slidably fitted on the ball screw guide shaft 5, and a guide shaft 5 The stopper plate 7 of the guide shaft 5, which is provided above, and the cylinder rod 33, which abuts via the thrust bearing 35, are arranged in the same straight line in the vertical direction.

A hopper 29 for supplying the molding material into the superheated cylinder 1 is connected to the superheated cylinder 1 via a pipe 28.

The 19 is arranged parallel to these components and controls
The electric motor is controlled by 30, and is fixed to the injection unit base 21 that holds the overheating cylinder 1 fixed. The input shaft 18 is connected to the electric motor 19 via a joint sleeve 20. Two clutches 16 and 17 (the clutch 16 is referred to as a metering / kneading clutch and the clutch 17 is referred to as an injection clutch) are fixed to the input shaft 18 at the upper and lower sides. The weighing / kneading clutch 16 can be connected to the input timing pulley 14, which is a timing belt.
It is connected via 12 to an output side timing pulley 10 fixed to the outer circumference of the spline nut 8 fitted to the spline shaft 3. Therefore, when the clutch 16 is connected to the pulley 14, rotation of the electric motor 19 drives the pulley 14,
The spline shaft 3 rotates via the timing belt 12, the timing pulley 10, and the spline nut 8, and the screw 2 rotates accordingly. The clutch 17 can be connected to the input side timing pulley 15, and the pulley 15 is connected to the output side timing pulley 11 fixed to the ball nut 6 via the timing belt 13. Therefore, when the clutch 17 is connected to the pulley 15, the ball nut 9 is rotated via the pulley 15, the timing belt 13, and the timing pulley 11 by the rotational driving of the electric motor 19, and the hollow ball screw 6 is vertically moved accordingly.

It should be noted that the hollow ball screw 6 is provided with a projection piece 31 whose cross section is shown in FIG. 1 (b), and is fixed to the injection unit base 21 at the bifurcated distal end of the projection piece 31 (not shown). ) By fitting the guide rod 32, the ball nut 9
The hollow ball screw 6 does not rotate with the rotation of, but can only move linearly with respect to the guide shaft 5.

The hollow ball screw 6 is slidably provided on the guide shaft 5 as described above, and is configured to move up and down as the ball nut 9 rotates. The upper end of the guide shaft 5 has a diameter larger than that of the hollow ball screw 6. Since the stopper plate 7 is fixed and the lower end of the guide shaft 5 is fixedly mounted on the spline shaft 3 having a diameter larger than that of the hollow ball screw 6, when the hollow ball screw 6 moves up and down, the stopper plate 7 abuts on the upper side. , And contacts the spline shaft 3 below. Therefore,
Since the stopper plate 7, the guide shaft 5, the spline shaft 3 and the screw 2 are integrally fixed to each other as described above, the hollow ball screw 6 is rotated by the rotation of the ball nut 9 which is interlocked with the rotational driving of the electric motor 19. The screw 2 can be vertically moved in the heating cylinder 1 by vertically moving and pushing out the stopper plate 7 or the spline shaft 3 located above.

The back pressure cylinder 22 is attached to the injection unit base 21 (not shown), is arranged on the same straight line as the stopper plate 7, the guide shaft 5, the spline shaft 3 and the screw 2 as described above, and moves the cylinder rod 33 up and down. Move it.
As a result, the cylinder rod 33 can be lowered to press the stopper plate 7 and apply back pressure to the screw 2. Reference numeral 23 denotes a back pressure cylinder pressure regulator, which is connected to the back pressure cylinder 22 via a tube 34 and is connected to a compressed fluid (air or the like) supply source (not shown). The pressure control of the back pressure cylinder 22 is controlled by the pressure regulator 23.
By controlling the pressure of the compressed fluid.

With the back pressure mechanism having such a configuration, thrust can be applied to the screw 2 against the pressure generated in the molten molding material that is gradually accumulated in front of the screw 2 due to the measurement and kneading of the molding material. It is possible to prevent the generation of bubbles and the like that occur in the molten molding material when no back pressure is applied. Further, since the back pressure mechanism of the present embodiment is configured to perform the pushing operation of the back pressure cylinder 22 as described above, the configuration is simple, and its control source can also be configured by a simple mechanism. Can be done easily.

The thrust bearing 35, which is provided at the lower end of the cylinder rod 33 so as to contact the stopper plate 7,
As shown in Figure (c), two angular bearings 3
Cylindrical member having bearings 36 and 37, inner races of bearings 36 and 37 being fixed by stepped portions of cylinder rod 33 and nuts 38 screwed from the tip of cylinder rod 33, and outer races having shoulder portions 39. Cylindrical member 42 having 40 and protrusion 41
When the cylinder rod 33 contacts the stopper plate 7, the cylindrical members 40 and 42 rotate and the cylinder rod 33 does not rotate because the bearings 36 and 37 are interposed.

24, 25, 26, 27 are sensor groups for detecting the stroke of the screw 2 or the hollow ball screw 6, 24 is a suck back completion detection sensor, 25 is a measurement completion detection sensor, 26 is a screw / overrun detection sensor, 27 Is a hollow ball screw standby position sensor. Each sensor 24,25,26,27
Is attached so that the detection position can be adjusted by appropriately moving the injection unit base 21.

In this configuration, each sensor is a reflective photoelectric sensor,
The side surface of the stopper plate 7 is used as a sensor dog for the suck back completion detection sensor and the weighing completion detection sensor, and the side surface of the hollow ball screw 6 is used as a sensor dog for the hollow ball screw standby position sensor. Each sensor is turned on when it moves to the position where the light of the sensor hits. Further, the overrun detection sensor substitutes the side surface of the hollow ball screw 6 as a sensor dog, and the sensor is turned on when the hollow ball screw moves to a position where the light of the sensor does not hit.

In the present embodiment, the stroke path length of the moving stroke of the screw during suck back is detected by the weighing detection sensor 25 and the suck back completion detection sensor 24. Weighing completion sensor 25 and suck back completion detection sensor 24
Is a suck back amount, and after the position of the measurement completion detection sensor 25 is set by the amount of the molten molding material accumulated in front of the screw 2, the position of the suck back completion detection sensor 24 is set. . As a result, the stopper plate 7
After the measurement completion detection sensor 25 is turned on at the upper end of the, the screw is detected to have moved by the distance required for suck back.

Although not shown in FIG. 1 (a), when actually performing injection molding, a molding die is arranged at the tip of the heating cylinder 1, and the die is opened / closed or clamped. Devices and the like are provided.

Further, in this embodiment, a pressure holding timer and a cooling timer are provided in the control device 30 in order to measure the pressure holding time and the cooling time of the molded product in the mold cavity.

Next, the operation of the electric injection apparatus of this embodiment configured as described above will be described with reference to the operation diagrams of FIGS. 3A to 3E and the flowchart of FIG. The symbol indicated by S in parentheses indicates a step in the flowchart of FIG.

In FIG. 3 (a), the hollow ball screw 6 is in a position where the hollow ball screw standby position sensor 27 is turned on, and at the same time, the back pressure cylinder 22 and the measuring clutch 16 are also turned on (S1).
At this time, the motor 19 rotates clockwise (CW; clockwise)
Is rotated (S2), screw 2 is the timing belt
12, rotated through the spline nut 8 and the spline shaft 3, and rises in the superheat cylinder 1 while measuring and kneading the molding material supplied in the superheat cylinder 1. At the same time, the back pressure is applied to the screw 2 by the back pressure cylinder 22 through the stopper plate 7, the guide shaft 5, and the spline shaft 3.

Next, when the screw 2 moves up to the state shown in FIG. 3 (b), the measurement completion detection sensor 25 receives an ON signal (S3). Here, the motor 19 is stopped (S4). Further, the measuring clutch 16 and the back pressure cylinder 22 are turned off (S5), and the measuring / kneading is completed.

On the other hand, when the molding material is weighed and kneaded in the cylinder 1 as described above, the molding material that has been weighed and kneaded in the previous step is stored in the mold (not shown) provided below the cylinder 1. Where the holding pressure, cooling, and removal of the molded product are performed. However, at this time, suck back is required to prevent the molding material kneaded in the cylinder 1 from leaking from the injection port of the cylinder 1.

Therefore, as described above, the measurement / kneading in the cylinder 1 is completed, the motor 19 is turned off (S4), and the measurement / kneading clutch 1
Turn off 6 and back pressure cylinder 22. When the injection clutch 17 is turned on (S6), the motor 19 is rotated clockwise (CW) (S7). As a result, the timing belt 13,
When the hollow ball screw 6 rises via the ball nut 9, the stopper plate 7 is pushed up and suck back is performed. In this suck back, as described above, the hollow ball screw 6 has the suck back completion detecting sensor 24 shown in FIG. 3 (c).
It is carried out until it goes up to the position to turn on (S8).

At this time, the motor 19 is stopped (S9), and suck back is completed. In FIG. 3 (c), a is a suck back stroke, and b is a hollow ball screw moving stroke during suck back.

After suck back is completed as described above and the cooling timer counts up (S10), the mold is unfastened (S11), the mold is opened (S12), and the molded product is taken out (S13). , Close the mold again (S14) and close the mold (S1
Do 5).

Next, in order to inject the molding material mixed in the mold clamped as described above, the motor 19 is rotated counterclockwise (CC
W: Rotate to counter clock width (S1
6). At this time, since the injection clutch 17 is still in the ON state, when the motor 19 is rotated counterclockwise, a downward thrust is applied to the hollow ball screw 6. At this time, the hollow ball screw 6 is first fed idle, and then the lower end of the hollow ball screw 6 hits the spline shaft shoulder 3a to push the screw 2 downward as shown in FIG. Injection into the inside is performed. Since the back pressure cylinder 22 is turned off, the cylinder rod 33 remains in the position shown in FIG. 3 (c).

The control of the motor 19 at the time of injection is performed by the control device 30, and the change in the current consumption value of the motor 19 at the time of completion of injection is detected (S1
8), the control of the motor for injection is switched from speed control (S17) to current value control (S19), whereby injection is completed, and the pressure shifts to a holding pressure state where a constant pressure is applied to the molding material. That is, the rotation speed of the motor 19 is kept constant, the descending speed of the ball screw 6 is kept constant, and the injection is performed at a constant speed.
However, during this injection, the pressure of the molding material increases as the molding material is filled in the mold cavity, so to maintain a constant injection speed as described above, gradually increase the current. Must flow to motor 19.
Therefore, by setting a constant current value and setting the time when the consumption current value reaches this constant value as the completion time of injection, it is possible to detect the completion time of injection by measuring the consumption current value. Then, at the time of completion of this injection, by switching the control so that the value of the electric current applied to the motor 19 becomes constant, a constant pressure can be applied to the molding material in the mold cavity to maintain the pressure.

After switching the motor 19 to the current value control, the pressure holding timer starts counting (S19). When FIG. 3 (d) shows the injection completed state, c is the hollow ball screw moving stroke and d is the injection stroke. Incidentally, reference numeral 26 is a screw overrun detection sensor, and in a normal operation, the injection completion state is reached at a position above the sensor 26.

Next, when the holding pressure timer counts up (S2
0), the motor 19 is stopped to complete the holding pressure, and the cooling timer starts counting (S21).

When the holding pressure is completed as described above, in order to prepare for the next weighing and kneading, the motor 19 is rotated clockwise with the injection clutch 17 kept in the ON state (S22), and the hollow ball screw 6
Until the hollow ball screw standby position sensor 27 is turned on, and the hollow ball screw standby position sensor 27 is turned on (S2
3) By the way, the motor 19 is stopped (S24), and the hollow ball screw 6 is made to stand by at that position as shown in FIG. 3 (e). At this time, the injection clutch 17 is turned off (S2
Five). In FIG. 3 (e), e is a hollow ball screw moving stroke.

After going through the steps above, weigh the clutch 16 again.
By turning on the back pressure cylinder (S1) and repeating the above steps, kneading and weighing of the molding material, back pressure, suck back and injection can be performed.

As shown in the above description of the operation, in the present invention, the hollow ball screw 6 is in a state where it is lifted and stopped to the measurement standby position and the injection clutch 17 is disengaged, that is, the screw 2
Measurement and kneading are performed in a state where the drive source of the motor 19 traveling straight ahead is completely separated. That is, at the time of measuring and kneading, only the rotational driving force is applied to the screw 2,
Since the vertical direction is completely separated from the linear drive system (motor 19, ball screw 6, ball nut 9, etc.), only the vertical thrust force due to the measurement of the molding material is generated in the vertical direction of the screw 2. Screw 2 with the progress of
Will rise. At this time, the back pressure applied to the screw 2 to suppress the variation in measurement is determined only by the output of the back pressure cylinder 22, and the volume of the measured molding material of the screw 2 detected by the measurement completion detection sensor 25. Determined by travel path length.

In this embodiment described above, the length of the travel path of the screw is detected by adjusting the position of the measurement completion detection sensor 25 and the position of the suckback completion detection sensor 24. Therefore, the suckback adjustment can be easily performed.

In this embodiment, photoelectric sensors are used as the sensors 24, 25, 26, 27, but the switches are switched by bringing the end portions of the stopper plate 7 into contact with the micro switches using the micro switches. You may do it.

The electric injection device to which the present invention is applied can be modified in various ways.

For example, in the above embodiment, the spline shaft 3 is provided at the rear end of the screw 2 and the hollow ball screw guide shaft 5 is provided at the rear end thereof. However, the hollow ball screw guide shaft is provided at the rear end of the screw and the spline shaft is provided at the rear end thereof. With
It is also possible to use a linear mechanism and a rotating mechanism in this order. In this case, the back pressure cylinder is provided so as to press the rear end of the spline shaft. In the above embodiment, the guide shaft 5 has a smaller diameter than the spline shaft 3, and the boundary between the guide shaft 5 and the spline shaft 3 is the locking portion below the hollow ball screw 6.
When the guide shaft 5 has a diameter larger than that of the spline shaft 3, for example, a flange portion having a diameter larger than the diameter of the hollow ball screw is provided at the boundary portion to form the locking portion of the hollow ball screw.

In the above embodiment, the rotary shaft of the rotary mechanism is the spline shaft, and the rotary driving force transmission mechanism is the timing pulley 14, the timing belt 12, the timing pulley 10, and the spline nut 8. However, the rotary shaft is a wide gear, and A gear that meshes with the input shaft 18 may be attached, and the gear attached to the input shaft 18 may slidably transmit the rotational force to the wide gear.

Further, also in the rectilinear mechanism, instead of using the timing belt 13, a gear may be attached to the ball nut 9, and a gear that meshes with this may be attached to the input shaft 18 as a rotary driving force transmission mechanism in the rectilinear mechanism. .

Further, in the above-described embodiment, the rotating mechanism and the rectilinear mechanism are driven by one motor 19 and the two clutches 16 and 17, but the clutch is abolished and one is provided for each of the rotating mechanism and the rectilinear mechanism. You may use the electric motor of.

(Advantages of the Invention) The present invention is as described above in detail, and a heating cylinder vertically arranged with an injection port for injecting a molding material facing downward, a screw housed in the heating cylinder, and the screw. A vertically arranged spline shaft connected to the upper end of the ball screw, a ball screw coaxially provided on a guide shaft continuous to the upper end of the spline shaft, a ball nut screwed to the ball screw, and the upper end of the ball screw. ,
In order to apply a back pressure to the guide shaft, a cylinder rod that operates by control of a compressed fluid in a back pressure cylinder is provided, and the spline shaft and the ball nut,
The electric power is transmitted from the electric motor through the rotary motion transmitting means that gives the rotary motion and the straight motion transmitting means that gives the straight motion, respectively, and detects the stroke path length in the moving stroke of the screw at the time of suckback. The detection sensor is arranged corresponding to the moving area of the ball screw so that the position can be set according to the amount of the injection molding material.

Therefore, each component such as the rotational movement and the linear movement related to the screw, and the back pressure applying means (the back pressure cylinder or the cylinder rod thereof) capable of supporting suck back according to the injection amount is set in the axial direction of the screw. It is possible to obtain the effect that the floor projection area can be made as small as possible by arranging in series with the above in a vertical structure.

Further, the stroke path length during suck back can be easily determined by setting the position of the detection sensor, and it is possible to deal with the adjustment of the suck back amount according to the amount of injection molding material.

[Brief description of drawings]

FIG. 1 (a) is a conceptual explanatory view of an electric injection device according to one embodiment of the present invention, and FIG. 1 (b) is II in FIG. 1 (a).
-II sectional view, FIG. 1 (c) is III in FIG. 1 (a)
-III cross-sectional view, FIG. 2 is a perspective view of the rotating mechanism, the rectilinear mechanism, the back pressure mechanism, the clutch, and the electric motor shown in FIG.
FIG. 3 and FIG. 4 are an operation explanatory view and a flow chart in the above embodiment, respectively. 1 …… Heating cylinder 2 …… Screw 3 …… Spline shaft 3a …… Spline shaft shoulder 5 …… Hollow ball screw guide shaft 6 …… Hollow ball screw 7 …… Stopper plate 8 …… Spline nut 9 …… Ball nut 10, 11 …… Output side timing pulley 12,13 …… Timing belt 14,15 …… Input side timing pulley 16,17 …… Clutch 18 …… Input shaft 19 …… Electric motor 21 …… Injection unit base 22 …… Back pressure Cylinder 23 …… Pressure regulator 24 …… Suck back completion detection sensor 25 …… Weighing completion detection sensor 26 …… Screw / overrun detection sensor 27 …… Hollow ball screw standby position sensor 30 …… Control device 33 …… Cylinder rod

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mitsuo Arai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A 61-266218 (JP, A) JP-A 63 -1517 (JP, A) Actually opened 63-139915 (JP, U)

Claims (1)

(57) [Claims] 1. A heating cylinder vertically arranged with an injection port for injecting a molding material facing downward, a screw housed in the heating cylinder, and a vertically arranged spline shaft connected to an upper end of the screw. A ball screw coaxially provided on a guide shaft continuous to the upper end of the spline shaft, a ball nut screwed to the ball screw, and a back pressure applied to the guide shaft corresponding to the upper end of the ball screw. A cylinder rod that operates by controlling the compressed fluid in the back pressure cylinder, and applies a rotational motion transmitting means for applying a rotational motion and a linear motion transmitting means for applying a linear motion to the spline shaft and the ball nut, respectively. The power is transmitted from the electric motor via the motor, and the process path length in the screw moving process during suck back is detected. The detection sensor, to be positioned set according to the amount of the injection molding material, electric vertical injection apparatus characterized by being arranged to correspond to the movement region of the ball screw.