INJECTION MOLDING MACHINE

Abstract: An improvement in the construction of a unit base (5), on which an injection unit (4) is placed, in an injection molding machine, an object of this invention being to simplify the construction of the unit base (5), enable the ball screw and nut (19, 20) in a nozzle touch mechanism (6) to be taken out easily, prevent the ball screw (19) from being whirled, and enable the nozzle touch pressure to be identified realistically and continuously with ease. The machine is formed by combining the front support portion (11) of the unit base with the rear support portion (12) thereof by a connecting pipe (13). A longitudinally extending through passage (28) connected to the connecting pipe is provided in a lower portion of the unit base (5), and the ball screw and nut (19, 20) of the nozzle touch mechanism in this through passage. The rear end portion of the ball screw (19) is supported. An indicator bar (40) is attached to a pressure plate (17) adapted to be moved when a touch pressure increases, and the moving condition of the pressure plate is indicated in a display window.

Description: The present invention relates to an improvement of a carriage unit of an injection unit and a nozzle touching mechanism in an injection molding machine. In an injection molding machine, a mold clamping unit and an injection unit are arranged facing each other on a base, and the injection unit is moved back and forth for nozzle touching and release therefrom, with respect to the mold clamping unit. For this purpose, the injection unit is placed on a carriage unit which can move back and forth on the base. The carriage unit includes a front supporting portion and a rear supporting portion, which conventionally are formed integrally with each other or connected by means of a plurality of frame members. The junction between these portions is required to have a structure capable of withstanding a compressive force or tensile force to which it is subjected during nozzle touching operation of the injection unit. JP-A-1-294 024 discloses these front and rear portions being connected by bars. Since various devices and cables are arranged intensively in this region, the junction is required to be built as simple as possible. Since the various cables are connected to the injection unit so that they can move back and forth together with the injection unit, they must be arranged such that they will not interfere with one another or run against some other members. The injection unit is moved in the longitudinal direction by means of a nozzle touching mechanism. Usually, the nozzle touching mechanism includes a screw and a ball bearing nut, which are arranged so that the injection unit can be moved back and forth by driving the screw which is screwed in the ball bearing nut fixed to the carriage unit of the injection unit. This screw-nut portion is adequately protected by a flexible cover or the like, so that such a cover must be removed at the time of inspection or replacement. According to the conventional arrangement and construction of the carriage unit and the nozzle touching mechanism, however, when removing the screw of the nozzle touching mechanism, the injection unit and the carriage unit have to be removed from the base. Thus, removing the screw not only requires the removal of other parts but also requires time-consuming centering and adjustment after remounting. Furthermore, in the conventional injection unit, there is provided no means for supporting the portion of the screw which projects backward from the ball bearing nut. Thus, when the injection unit is in an advanced position where the projecting rear end portion of the screw is long, the screw tends to whirl, so that the screw and ball bearing nut may possibly suffer uneven wear. Moreover, in the stage of adjusting of the injection molding machine, nozzle touching of the injection unit is sometimes made manually. In this case, the operator is always required to know the position of the injection unit so that he will be able to know the level of the touching pressure at least roughly even after the touching. Since the nozzle touching operation of the injection unit is controlled in accordance with the position of a dog relative to a limit switch or proximity switch, it is difficult to display the position of the injection unit continuously on a display unit by using intuitive means such as graphic forms as the display unit is under the control of NC device. Therefore, the position of the injection unit is indicated only numerically or only by notifying the arrival of the unit at a predetermined position. Thus, it is difficult to know the relative position of the injection unit, and so still there is room for improvement for the operating procedure of the conventional injection molding machine. A preferred embodiment of the present invention provides an improved injection molding machine which is provided with a carriage unit of simple construction, and in which a screw and a ball bearing nut of a nozzle touching mechanism can easily be taken out, or the screw is prevented from whirling, or an operator can easily know the position of an injection unit relative to a mold clamping unit and nozzle touching pressure. According to the present invention, there is provided an injection molding machine comprising a mold clamping unit and an injection unit mounted facing each other on a base, the injection unit being placed on a carriage unit capable of being moved in the longitudinal direction on the base by means of a nozzle touching mechanism; in which the carriage unit includes a front supporting portion and a rear supporting portion connected to each other by means of a longitudinally extending connecting pipe. According to a preferred embodiment of the invention, the carriage unit is formed having a longitudinally penetrating through passage with the axis thereof in alignment with the axis of the connecting pipe, and is fitted with a ball bearing nut of the nozzle touching mechanism and a longitudinally disposed screw mating with the nut in a threaded manner so that the respective axes of the nut and the screw are in alignment with the axis of the through hole, a flange of the ball bearing nut being formed having a diameter smaller than that of the connecting pipe so that the screw and ball bearing nut can be drawn out from behind the carriage unit through the connecting pipe. According to another preferred embodiment of the invention, the carriage unit is fitted with a bearing pipe arranged inside the connecting pipe so that the axis of the bearing pipe is in alignment with that of the connecting pipe, the rear end of the screw of the nozzle touching mechanism being inserted into the bearing pipe to be supported thereby for being movable in the longitudinal direction. According to another preferred embodiment of the invention, the rear end of the screw inserted into the bearing pipe is fitted with a bush having an outside diameter substantially equal to the inside diameter of the bearing pipe. According to another preferred embodiment of the invention, the bearing pipe is supported by bearing members arranged respectively in the front and rear portions of the connecting pipe so as to be slidable in the connecting pipe, a mounting plate connected to the rear end side of the bearing pipe being fixed to a stay integrally protruding from the rear supporting plate by bolt-nut connection, so that the screw and ball bearing nut can be drawn out from behind the carriage unit through the connecting pipe by releasing the mounting plate and the stay from the bolt-nut connection. Further, in an injection molding machine according to a development of the present invention, cables for the injection unit are separated into those for communication and those for power services, housed individually in corresponding cable supporting devices, and arranged on the portion of the base under the carriage unit. Further, in an injection molding machine according to another development of the present invention, the carriage unit is provided with a spring bearing portion; a spring for nozzle touching is mounted between the bearing portion and a backup plate arranged for longitudinal movement behind the bearing portion at a certain distance therefrom; a ball nut of screw and ball bearing nut means arranged in the longitudinal direction in the nozzle touching mechanism is fixed to the backup plate and threadedly engaged with a screw penetrating the bearing portion through threads; and an indicator rod having one end fixed to the backup plate is arranged so that a pointer at the distal end thereof faces an indicator window which is attached to a carriage unit cover. According to the present invention, as described above, the connecting pipe is used to securely but simply connect the front and rear supporting portions of the carriage unit. Where the through passage and the screw and ball bearing nut of the nozzle touching mechanism are arranged with their respective axes in alignment with that of the connecting pipe, the screw and ball bearing nut can be drawn out backward. Furthermore, where the rear end of the screw is inserted in the bearing pipe, the screw can thereby be prevented from whirling. According to the aforesaid development of the present invention, the cable supporting devices not only protect the cables, but also prevent communication and power lines from interfering with one another or with some other members. According to the aforesaid another development of the present invention, an operator can visually recognise the position of the injection unit or touching pressure by watching the position of the pointer through or by means of the indicator window. Brief Description of the Drawings Fig. 1 is a front view, partially in section, showing a mold clamping unit and an injection unit of an injection molding machine according to the present invention; Fig. 2 is a plan view showing a base of the injection molding machine of the present invention and a carriage unit for movably carrying the injection unit on the top surface of the base; Fig. 3 is a plan view showing a main part of cable supporting devices for holding cables for communication and power services arranged on the top surface of the base of the injection molding machine of the present invention; Fig. 4 is a front view, partially in section, illustrating main part of the cables for communication and power services from the base of the injection molding machine of the present invention connected to the injection unit side; Fig. 5 is a perspective view showing main part of a nozzle touching mechanism of the injection molding machine of the present invention to which a pointer indicating the touching pressure is attached; and Fig. 6 is a front view schematically showing the mold clamping unit and the injection unit placed on the base of the injection molding machine of the present invention. An injection molding machine 1 (Fig. 6) comprises a mold clamping unit 3 and an injection unit 4 mounted opposite to each other on a base 2. The injection unit 4 is placed on a carriage unit 5 (Figs. 1 and 2), which is movable in the longitudinal direction on the top surface of the base 2, and can be moved back and forth by means of a nozzle touching mechanism 6. Numerals 7a and 7b designate two parallel rails mounted in the longitudinal direction on the top surface of the base 2. The injection unit 4 has a nozzle 9 at the distal end of its cylinder assembly 8. Nozzle touching is accomplished as the nozzle is brought into contact with a sprue of a mold attached to the mold clamping unit 3. Further, a carriage unit cover 10 is attached to outer periphery of the carriage unit 5. The carriage unit 5 includes a front supporting portion 11 and a rear supporting portion 12, which are connected to each other by means of a connecting pipe 13. The connecting pipe 13 having a relatively large diameter is used to connect the front and rear supporting portions 11 and 12 to each other by fixing the flange rings 14a and 14b, fixed respectively on both ends of the connecting pipe 13, to the two supporting portions respectively with bolts. Both left- and right-hand sides of each of the front and rear supporting portions 11 and 12 are placed on the rails 7(a) and 7(b) of the base 2, so that the carriage unit 5, as a whole, can move in the longitudinal direction on the base 2. The front supporting portion 11 is provided with a pivot receiving hole 15 for swiveling the injection unit 4 at the center of its top surface with respect to the crosswise direction, and a spring bearing plate 16 is mounted on the front side. The spring bearing plate 16 has a through hole at its center part. Underlying the front supporting portion 11, a backup plate 17 having a center hole is separately formed for movement in the longitudinal direction. A stay 18 (Fig. 1) protrudes downward integrally from the lower part of the rear supporting portion 12. The nozzle touching mechanism 6 includes a screw 19 and a nut 20. The front end of the screw 19 is coupled to an output gear 23 of a reduction and braking mechanism 22, which is connected to a motor 21 for nozzle touching. On the other hand, the ball bearing nut 20 is inserted into the hole of the backup plate 17 from behind to cause a fixing flange 24 to contact the rear face of the backup plate 17, and is fixed to the front face of the backup plate 17 by means of bolts 25. The rear end of the screw 19 passes through the hole of the spring bearing plate 16, and is screwed in the ball bearing nut 20 so that its rear end portion projects backward and beyond the ball bearing nut 20 (Fig. 1). One end of each of longitudinal guide bars 26, arranged on the left and the right, is fixed to the spring bearing plate 16, and a spring 27 is mounted on each bar 26 (Fig. 5). The backup plate 17 is fitted on the guide bars 26 so that the springs 27 are compressed between the plate 17 and the spring bearing plate 16. The respective axes p and q of the connecting pipe 13 and the ball crew 19, mounted in this manner, are in alignment with each other (Fig. 1), and a longitudinal through passage 28 is formed penetrating the front supporting portion 11, connecting pipe 13, and rear supporting portion 12. The flange 24 of the ball bearing nut 20 is designed so that its diameter is smaller than those of the through passage 28 and the connecting pipe 13. The principal parts of the screw 19 and ball bearing nut 20 are situated in the portion of the through passage 28 right under the front supporting portion 11. A bearing pipe 29 is disposed in the connecting pipe 13 with its axis r in alignment with the axis p of the connecting pipe 13, and is mounted inside the connecting pipe 13 by means of front and rear bearing members 30(a) and 30(b). A transversely elongated mounting plate 31 is fixed to the rear end portion of the bearing pipe 29. As both ends of the plate 31 are fixed to the stay 18 from behind by means of bolts 32, the pipe 29 can be mounted on the carriage unit 5. The bearing members 30(a) and 30(b) are simply inserted into the connecting pipe 13 so that they can be moved back and forth by being pulled and pushed in the connecting pipe 13. Further, the front portion of the bearing pipe 29 projects from the front end of the connecting pipe 13, and penetrates the lower part of the front supporting portion 11, thereby supporting the rear end portion of the screw 19. In order to make this state of support stabler, a plastic bush 33 is attached to the rear end of the screw 19. The outside diameter of the bush 33 is substantially equal to the inside diameter of the bearing pipe 29 so that there is no rattling between the bush 33 and the inner wall of the pipe although the bush is movable in the longitudinal direction. Thus, the screw 19 and ball bearing nut 20 of the nozzle touching mechanism 6, along with the bearing pipe 29, can be drawn out behind the carriage unit 5 after going through the following steps: disconnecting the reduction and braking mechanism 22 from the screw 19, removing the bolts 25 to disconnect the backup plate 17 from the ball bearing nut 20, and further removing the bolts 32 to remove the mounting plate 31 and the carriage unit 5. In mounting the elements, in contrast with this, the screw 19 and ball bearing nut 20 are first to be attached and fixed; the bearing pipe 29, fitted with the bearing members 30(a) and 30(b), is then to be inserted into the connecting pipe 13 from behind so that its front end can be fitted on the rear end of the screw 19; and the mounting plate 31 is to be fixed to the stay 18. Communication cables 34 and power cables 35 (Fig. 4) are connected to the injection unit 4 from the side of the base 2. These cables 34 and 35, which are divided into those for communication and those for power services, are housed in cable supporting devices 36 and 37, respectively. These cable supporting devices 36 and 37 are arranged on the top surface of the base, and their respective distal end portions, directed to the injection unit 4, are fixed to the injection unit 4 by means of connecting cases 38 and 39. Thus, the cables 34 and 35 are arranged in order on the portion of the top surface of the base 2 which underlies the carriage unit 5. Since the two cable supporting devices are used, the height of each cable supporting device can be reduced, so that the devices can easily be stored under the carriage unit 5 without interference with any other members. Further, one end of an indicator rod 40 is fixed to the backup plate 17 which is associated with the nozzle touching mechanism 6. The indicator rod 40 is a slender rigid rod having a pointer 41 on the other end, and is used to indicate the movement of the backup plate 17 by means of the pointer 41. The pointer 41 is located inside an indicator window 42, which is provided on the unit carriage cover 10 together with a scale. When the nozzle touching mechanism 6 continues to be driven in the direction to advance the injection unit 4 after the nozzle touching operation, the springs 27 are compressed without causing the movement of the injection unit 4, thereby producing a nozzle touching pressure. In this case, the backup plate 17 also advances, and an operator can measure the level of the current touching pressure by the movement of the pointer 41, though only roughly. The above is a description of an embodiment, and the present invention is not limited to the illustrated specific arrangement. For example, the pointer 41 may be formed of an electrical contact which moves gradually. In this case, the scale of the indicator window 42 is composed of a row of light emitting diodes (LEDs) so that the position can be indicated by causing the LEDs to glow by being in contact with the pointer. In this case, a switch for changing the type of diodes to be turned on when the backup plate 17 is moved forward for a predetermined distance after the nozzle touching operation may be additionally provided so that the color of luminous indication can be changed when the nozzle touching has occurred. When arranged as described in the foregoing, the present invention can provide the following various effects. The front and rear supporting portions 11 and 12 of the carriage unit 5 being coupled by means of the connecting pipe 13, the construction of the carriage unit 5 is enabled to have a simple construction. Besides, the high rigidity of the pipe structure contributes to the increase in the rigidity of the whole carriage unit 5 during the nozzle touching operation. The screw 19 and ball bearing nut 20 of the nozzle touching mechanism 6 can be taken out without dismantling the injection unit section, so that the screw 19 and ball bearing nut 20 can easily be inspected, repaired, and replaced. The principal parts of the screw 19 and ball bearing nut 20 are housed in the portion of the through passage right under the front supporting portion 11, thereby providing dustproof effect and resulting longer life to the screw 19 and ball bearing nut 20. Since the rear end of the screw 19 is supported by the bearing pipe, the screw 19 can be prevented from whirling, thereby preventing uneven wear of the screw and nut mechanism. The cables 34 and 35 are separated into those for communication and those for power services, arranged in order and protected by means of the cable supporting devices 36 and 37, respectively, thereby preventing the occurrence of awkward situation resulting from the troubles such that the cables functionally interfere with one another or come into contact with some other members causing mutual damage during the operation of the injection molding machine. The operator can realize the nozzle touching pressure by the position of the pointer on the indicator window of the unit carriage cover 10.

Claims: An injection molding machine comprising a mold clamping unit (3) and an injection unit (4) facing each other on a base (2), the injection unit (4) being mounted on a carriage unit (5) capable of being moved in the longitudinal direction on the base (2) by means of a nozzle touching mechanism (6), wherein the carriage unit (5) includes a front supporting portion (11) and a rear supporting portion (12) connected to each other, and characterised in that said front and rear supporting portions (11, 12) are connected to each other through longitudinal ends of a connecting pipe (13). An injection molding machine according to claim 1, wherein said carriage unit (5) includes a longitudinally penetrating through passage with the axis thereof in alignment with the axis of the connecting pipe (13), and is fitted with a ball bearing nut (20) of the nozzle touching mechanism (6) and accommodates a longitudinal ball bearing screw (19) mating with the nut (20) in a threaded manner so that the respective axes of the nut (20) and the screw (19) are in alignment with the axis of said through passage, a flange (24) of the ball bearing nut (20) being formed to have a diameter smaller than that of the connecting pipe (13) so that the screw (19) and ball bearing nut (20) can be drawn out from behind the carriage unit (5) through the connecting pipe (13). An injection molding machine according to claim 1 or 2, wherein said carriage unit (5) is fitted with a bearing pipe (29) arranged inside the connecting pipe (13) so that the axis of the bearing pipe (29) is in alignment with the axis of the connecting pipe (13), the rear end of the screw (19) of the nozzle touching mechanism (6) being inserted into the bearing pipe (29) and supported therewith so as to be movable in the longitudinal direction. An injection molding machine according to claim 3, wherein the rear end of said screw (19) inserted into said bearing pipe (29) is fitted with a bush (33) having an outside diameter substantially equal to the inside diameter of the bearing pipe (29). An injection molding machine according to claim 3 or 4, wherein said bearing pipe (29) is supported by bearing members (30a, 30b) arranged individually in the front and rear portions of the connecting pipe (13) so as to be slidable in said connecting pipe (13), and a mounting plate (31) connected to the rear end side of the bearing pipe (29) is fixed to a stay (18) integrally protruding from said rear supporting portion (12) by bolt-nut connection (32), so that the screw (19) and ball bearing nut (20) can be drawn out from behind the carriage unit (5) through the connecting pipe (13) by releasing the mounting plate (31) and the stay (18) from the bolt-nut connection (32). An injection molding machine according to any one of the preceding claims, wherein cables for the injection unit are separated into those for communication (34) and those for power services (35), housed individually in corresponding cable supporting devices (36, 37), and arranged on the portion of the base (2) under the carriage unit (5). An injection molding machine according to any one of the preceding claims, wherein the carriage unit (5) is provided with a spring bearing portion (16); a spring (27) for nozzle touching is mounted between said spring bearing portion (16) and a backup plate (17) arranged for longitudinal movement behind said bearing portion (16) at a certain distance therefrom; a ball bearing nut (20) of screw and nut means arranged in the longitudinal direction in the nozzle touching mechanism (6) is fixed to said backup plate (17) and engaged with a ball screw (19) penetrating said spring bearing portion (16) through threads; and characterised by an indicator rod (40) having one end fixed to the backup plate (17) and arranged so that a pointer (41) at the distal end thereof faces an indicator window (42) which is attached to a carriage unit cover (10). An injection molding machine according to claim 7, wherein said pointer (41) is formed of an electrical contact, and said indicator window (42) is composed of a row of light emitting diodes.

Inventors: ITO SUSUMU, KOJIMA KUNIO, ITO, SUSUMU, KOJIMA, KUNIO, ITO, SUSUMU, FANUC MANSHONHARIMOMI, KOJIMA, KUNIO, FANUC DAI-3 VIRA-KARAMATSU
Applicants: FANUC LTD, FANUC LTD.
Application year: 1993
Main classification: B29C45
IPC codes: B29C45