Electric injection mechanism

Abstract

The object of the present invention is to allow to perform easily the centering of the injection heating cylinder and the screw driver by a simple means even after the assembly, by providing an electric injection mechanism with a height adjustment means of the screw driver. A front plate provided with an injection heating cylinder 4 having a screw 3 installed inside at the front middle and a rear plate 2 provided with an electric motor 5 for injection-driving are rested on and fixed to the installation member 7. The front and rear plates 1, 2 are linked by means of a plurality of guide bars 6 installed right and left between the plates. The screw driver 10 is inserted into the guide bar 6 and disposed movably forward and backward between the plates. A driving means connected to the electric motor 5 and composed of a ball screw shaft 11 and a ball nut member 12 is installed over the screw driver 10 and the rear plate 2. A centering member 16 interposed between the installation means 7 for slidably supporting the screw driver 10 and, moreover, provided with a height adjustment means is installed at lower both sides of the screw driver 1.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention concerns an electric injection mechanism for driving the screw injection by an electric motor.

[0003] 2. Detailed Description of the Prior Art

[0004] The electric injection mechanism having an electric motor such a servomotor or the like as driving source, and injection-driving a screw by converting rotation movement by the electric motor into liner movement by a ball screw shaft and a ball nut member, includes one adopting a single ball screw shaft and one adopting a plurality of ball screw shafts.

[0005] In any of these types, a screw driver is inserted movably forward and backward into a guide bar between a pair of front and rear plates, and the ball screw shaft rotating by the electric motor engages with the ball nut member installed in the screw driver. Further, the rear end of a screw in an injection heading cylinder mounted at the front middle of the front plate is rotatably linked to the front middle of the screw driver.

[0006] In such a configuration, if the injection heating cylinder and the screw driver are decentered even slightly in the mounting, the injection heating cylinder and the screw therein are also decentered provoking gnawing or break and, moreover, the parallelism with a guide bar supporting the screw driver goes wrong, increasing the sliding resistance against the movement of the screw driver, and inconveniences of control or troubles or others appear easily by these causes.

[0007] The centers of the injection heating cylinder and screw driver are defined by the processing accuracy or the assembling accuracy of respective members composing an injection mechanism, and it is claimed that it is extremely difficult to adjust the misalignment after completion of the assembling. However, as it is pretended that the misalignment often appears in the height direction by the effect of the load, and the misalignment during the service is caused by the inflection of the guide bar due to the load of the screw driver, most of problems due to the misalignment shall be resolved, if the height of the screw driver can be adjusted by any means, even after the assembling.

[0008] The present invention devised in consideration of the situation mentioned above has an object to provide a novel electric injection mechanism allowing to adjust the height of the screw driver by an extremely simple means after the assembling, align easily the injection heating cylinder and the screw driver easily, and prevent misalignment during the operation.

SUMMARY OF THE INVENTION

[0009] According to the object, the present invention is the one, comprising a front plate provided with an injection heating cylinder having a screw inside at the front middle, a rear plate provided with an electric motor for injection-driving, an installation member affixing both plates, a plurality of guide bars installed at the right and at the left between the plates by linking with the pair of front and rear plates, a screw driver disposed movably forward and backward between the plates by inserting into the guide bars and a driving means comprised of ball screw shaft and ball nut member disposed over the screw driver and the rear plate by connecting with the electric motor, wherein a member for centering the injection heating cylinder and screw driver, slidably supporting the screw driver, being interposed between the installation member, and having a height adjustment means, is installed at both sides of the lower portion of the screw driver.

[0010] In addition, the driving means is the one, comprised of a pair of ball screw shafts rotatably juxtaposed over the front plate and rear plate, and a pair of the ball nut members at both sides of the screw driver, installed in the screw driver and engaging respectively with the ball screw shafts.

[0011] Further, the centering member is the one, comprised of a pair of wedge-shape members overlapping alternately by forming the contact surface respectively as the slant surface, both are linked relatively movably by an adjustment screw, the one is affixed to the bottom face of the screw driver, while the other is put on the top face of the installation member.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1. a side view showing a part of the electric injection mechanism of the present invention by a section;

[0013] FIG. 2. section view along the line A-A of the same;

[0014] FIG. 3. a side view of essential parts of another embodiment;

[0015] FIG. 4. a side view of the electric injection mechanism of the present invention provided with a driving means by a pair of ball screw shaft wherein the electric motor is omitted;

[0016] FIG. 5. a section view along the line B-B of the same.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] In the drawing, 1 indicates a front plate and 2 a rear plate, the front plate 1 is provided with an injection heating cylinder 4 having a screw 3 for injection installed inside, rotatably and movably forward and backward, at the front middle, and the rear plate 2 is provided with an electric motor 5 of injection-driving by a servomotor or the like.

[0018] The pair of front and rear plates 1, 2 are linked to four corners by guide bars 6, 6, and at the same time, both sides of the lower portion are respectively fixed onto both ends of a pair of right and left installation members 7, for affixing on the top face of a foundation 9 of a machine base 8.

[0019] 10 indicates a screw driver, disposed movably forward and backward between the pair of front and rear plates 1, 2 and, the rear end of the screw 3 is rotatably linked to the front middle thereof. Also, a ball nut member 12 engaged with a ball screw shaft 11 born rotatably by the rear plate 2 is mounted integrally to the rear middle of the screw driver.

[0020] Though not shown in the drawing, an electric motor and a screw rotation mechanism of weighing the material is mounted on the screw driver 10.

[0021] A pulley 13 is attached to the outer end of the rear plate 2 of the ball screw shaft 11, and a timing belt 15 is wound around the pulley 13 and a pulley 14 of the electric motor 5. Thereby, the ball screw shaft 11 is rotated by the electric motor 5, the rotational movement is converted into a liner movement by the ball nut member 12, the screw driver 10 drives forward with the screw, and resin weighed in the front section of the injection heating cylinder 4 is injected.

[0022] 16 indicates an centering member of the injection heating cylinder 4 and screw driver 10, comprised of a pair of wedge-shape members overlapping alternately by forming a contact surface respectively as a slant surface, and both of them are linked relatively movably by an adjustment screw 17 on the side.

[0023] One of the centering members 16 is affixed as upper member 16a to the bottom face just under the guide bar of the screw driver 10, while the other is put as sliding lower member 16b on the top face of the installation member 7, between both sides of the lower section of the screw driver 10 and installation member 7, and the height of the screw driver 10 is changed together with a tie bar 6, by changing the degree of their mutual overlapping by rotating the adjustment screw 17, whereby the injection heating cylinder 4 and screw driver 10 can be aligned.

[0024] During the attachment of the centering member 16, it is preferable to put a sliding plate 18 on the top face, set the lower member 16b thereon, so that the forward and backward movement of the screw driver 10 generates smoothly, and the height adjustment position by the centering member 16 is maintained also during the operation, even when both sides of its lower section is in a state being always supported by the installation member 7.

[0025] Concerning also the attachment point of the centering member 16, though it is attached to two point at the front lower side of the screw driver 10, in the embodiment of FIG. 1 and 2, it is preferable to attach also to the rear section for performing the height adjustment and support of the screw driver 10 at front and rear four points, as shown in FIG. 3, according to the increase in size of the screw driver 10.

[0026] In the aforementioned embodiment, as the height of the screw driver 10 can be adjusted together with the tie bar 6 even after the assembly, by attaching the centering member 16, the centering of the injection heating cylinder 4 and the screw driver 10 can be performed easily only by adjusting the height of the screw driver 10 through the individual operation of right and left, or front and rear right and left centering members 16, 16, even in a case where such centering is required, from the processing accuracy or assembly state of the injection mechanism.

[0027] Besides, in the one adopting wedge-shape upper and lower members 16, 16 for the centering member 16, the structure is extremely simple and the attachment can be completed simply, and even a delicate misalignment can be rectified, as the height adjustment can be performed by changing the degree of overlapping of mutual slant faces through the screw rotation.

[0028] Still further, as both sides of the screw driver 10 is in a state grounded to the machine base side by the centering member 16, the screw driver side load is shared by both of the guide bar 6 and the centering member 16, whereby, allowing to prevent an misalignment caused by the flexion due to the load of the guide bar 6.

[0029] FIG. 4 and FIG. 5 shown embodiments of the electric injection mechanism provided with twin shaft type driving means. It should be appreciated that same parts as the embodiment shown in FIG. 1 to FIG. 3 are indicated by the same symbol.

[0030] In this embodiment also, a pair of front and rear plates 1, 2 are affixed to the machine base 8 by linking with guide bars 6, 6 at four corners, and the fixation is realized by resting and affixing the lower both sides on a disk-shape installation member 71 put on the top face of the foundation 9.

[0031] Besides, at both sides middle of the front and rear plates 1,2, a pair of ball screw shafts 11, 11 are installed, being rotatably supported in parallel with the guide bars 6, 6. The read end of the ball screw shaft 6, 6 is connected on an electric motor for injection-driving (not shown).

[0032] A screw driver 10 is supported movably forward and backward by inserting into the guide bar 6, 6, and in the middle of right and left both side of the screw driver 10, a pair of ball nut members 12, 12 moving with the screw driver 10 on the ball screw shaft, engaging with the ball screw shaft 11 is installed inside.

[0033] A centering member 16 of the screw driver 10 is installed between the front and rear both sides of the lower portion wherein the guide bar 6, 6 of the screw driver 10 is inserted and the installation member 71. The centering member 16 is comprised of a pair of wedge-shape members overlapping alternately by forming a contact surface respectively as a slant surface, and both of them are linked relatively movably by an adjustment screw 17 on the side.

[0034] One of the centering members 16 is affixed as upper member 16a to the bottom face inside the guide bar of the screw driver 10, while the other is rested as lower member 16b on the top face at both sides of the installation member 71, and the height of the screw driver 10 is changed together with the tie bar 6, by changing the degree of their mutual overlapping by rotating the adjustment screw 17, whereby the injection heating cylinder 4 and screw driver 10 can be aligned.

[0035] In addition, during the attachment of the centering member 16, a sliding plate 18 is put on the top face at both sides of the installation member 71, the lower member 16b is rested thereon, so that a smooth sliding generates, even when both sides of the lower section of the screw driver 10 is in a state being always supported by the installation member 71.

[0036] As mentioned above, in the electric injection mechanism provided with a twin type driving means also, the height of the screw driver 10 after the assembly can be adjusted together with the tie bar 6, by attaching the centering member 16. Therefore, the centering can be performed easily, even in a case where such centering is required, from the processing accuracy or assembly state of the injection mechanism, and the screw driver side load can be shared through the centering member 16, allowing to prevent the misalignment caused by the flexion due to the load of the guide bar 6.

Claims

1. An electric injection mechanism, comprising: a front plate provided with an injection heating cylinder having a screw inside at the front middle, a rear plate provided with an electric motor for injection-driving, an installation member affixing both plates, a plurality of guide bars installed at the right and at the left between the plates by linking with said pair of front and rear plates, a screw driver disposed movably forward and backward between the plates by inserting into the guide bars, and a driving means comprised of ball screw shaft and ball nut member disposed over the screw driver and the rear plate by connecting with said electric motor, wherein: a centering member for centering said injection heating cylinder and screw driver, having a height adjustment means and slidably supporting the screw driver by being interposed between said installation member and said screw driver is installed at both sides of the lower portion of said screw driver.

2. The electric injection mechanism of claim 1, wherein: said driving means is comprised of a pair of ball screw shafts rotatably juxtaposed over said front plate and rear plate, and a pair of said ball nut members at both sides of the screw driver, installed in said screw driver and engaging respectively with the ball screw shafts.

3. The electric injection mechanism of claim 1, wherein: said centering member is comprised of a pair of wedge-shape members overlapping alternately by forming a contact surface respectively as the slant surface, both are linked relatively movably by an adjustment screw, the one is affixed to a bottom face of said screw driver, while the other is put on a top face of said installation member.