Patent Application
20220080639
This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2020-156099 filed on Sep. 17, 2020, the contents of which are incorporated herein by reference.
The present disclosure relates to a mold thickness adjusting device for a mold clamping device including a toggle mechanism.
Among mold clamping devices constituting an injection molding machine, a mold clamping device including a toggle mechanism includes: a fixed platen to which a fixed side mold is attached; a movable platen to which a movable side mold is attached; a mold clamping housing; a plurality of tie bars connecting the fixed platen and the mold clamping housing; a toggle mechanism provided between the mold clamping housing and the movable platen; and the like. Therefore, when the toggle mechanism is bent or stretched, the movable platen is driven with respect to the mold clamping housing, and the molds can be opened or closed to be clamped by the movable platen.
A mold clamping device including a toggle mechanism is provided with a mold thickness adjusting device, for example, as described in JP-A-2008-284788. The mold thickness adjusting device is configured as follows.
Tip ends of the tie bars are male screws which are screwed with tie bar nuts, respectively; and the tie bar nuts are accommodated in recesses formed in the mold clamping housing. Sprockets are fixed to the tie bar nuts, respectively, and one chain is wound around the sprockets such that the sprockets rotate in conjunction with each other. The mold clamping housing is provided with a motor for mold thickness adjustment, and the chain is also wound around a drive sprocket provided on the motor. Therefore, when the mold thickness adjusting motor is driven, all the tie bar nuts are rotated in conjunction with each other by the chain and the sprockets, and a distance between the fixed platen and the mold clamping housing, that is, a tie bar effective length is adjusted. That is, a mold thickness is adjusted.
In many mold clamping devices, the number of tie bars is four, and therefore, the number of tie bar nuts and sprockets is also four. Although the chain is wound around the four sprockets and the drive sprocket of the mold thickness adjusting motor, the chain needs to be wound around at least ¼ or more of a circumference of the sprocket so as not to idle with the sprockets. Since a mold opening and closing mechanism that drives the toggle mechanism is provided at a center of the mold clamping housing, the mold thickness adjusting motor and the drive sprocket need to be provided at a side portion of the mold clamping housing. Therefore, in order to satisfy a condition for winding the chain, generally, an idler sprocket needs to be additionally provided in the mold clamping housing, which causes a problem of an increase in the number of components. When the idler sprocket is provided, a load is applied to a rotation shaft of the idler sprocket, and thus there is a concern that the rotation shaft may be damaged.
Other problems and novel features will become apparent from description of the present specification and the accompanying drawings.
The present disclosure relates to a mold clamping device including a mold thickness adjusting device having a pre-determined configuration. The mold clamping device includes: a fixed platen; a movable platen; a mold clamping housing; a plurality of tie bars connecting the fixed platen and the mold clamping housing; a toggle mechanism provided between the mold clamping housing and the movable plate. The mold thickness adjusting device provided with such a mold clamping device is configured as follows. First, a tie bar nut is provided with each of a plurality of the tie bars. A rotation member is provided integrally with each of the tie bar nuts. One endless string-shaped force transmission member is wound around the plurality of rotation members. At least one of the plurality of tie bar nuts is determined as a drive target tie bar nut. A driving force is transmitted to the drive target tie bar nut directly by providing a rotation drive unit.
According to the present disclosure, a mold clamping device, which does not need to be additionally provided with a member such as an idler sprocket that may be damaged, can be provided.
Hereinafter, specific illustrative embodiments will be described in detail with reference to the drawings. However, the present disclosure is not limited to the following illustrative embodiments. The following description and drawings arc simplified as appropriate to clarify the description. In the drawings, the same elements are denoted by the same reference numerals, and repeated description thereof is omitted as necessary. In addition, hatching may be omitted to avoid complicating the drawings.
<Injection Molding Machine>
As shown in
<Mold Clamping Device>
The mold clamping device 3 according to the present illustrative embodiment is a toggle type mold clamping device. That is, the mold clamping device 3 includes a fixed platen 8 fixed to the bed B, a movable platen 9 provided to be slidable on the bed B so as to face the fixed platen 8, a mold clamping housing 11 provided to be slidable with respect to the bed B, four tie bars 12 connecting the mold clamping housing 11 and the fixed platen 8, and a toggle mechanism 13 provided between the mold clamping housing 11 and the movable platen 9.
The toggle mechanism 13 is driven by a ball screw mechanism 15, and the ball screw mechanism 15 is provided with a large pulley 16. As shown in
<Mold Thickness Adjusting Device>
The mold thickness adjusting device 25 according to the present illustrative embodiment is configured as follows. First, as shown in
Predetermined rotation members 29 are fixed to the tie bar nuts 27, and as shown in
The rotation members 29 that rotate the tie bar nuts 27 in synchronization with each other and the force transmission member 30 can be constituted by, for example, a pulley and a timing belt respectively, and any members can be used as long as the members can rotate in conjunction with each other. However, in the present illustrative embodiment, the rotation members 29 are formed of sprockets, that is, tie bar nut side sprockets 29, and the force transmission member 30 is formed of a chain 30. As shown in
The mold thickness adjusting device 25 according to the present illustrative embodiment is characterized in a method and a unit that drive the tie bar nuts 27. Specifically, one of the four tie bar nuts 27 is set as a drive target tie bar nut 27a, and the drive target tie bar nut 27a is rotated by a predetermined rotation drive unit. When the drive target tie bar nut 27a is rotated by the rotation drive unit, the other tie bar nuts 27 are rotated in conjunction with each other.
As shown in
In this way, in the mold thickness adjusting device 25 according to the present illustrative embodiment, the unit that drives the tie bar nuts 27 directly rotationally drives one tie bar nut 27, that is, the drive target tie bar nut 27a, and thus it is not necessary to separately provide a sprocket or the like that drives the chain 30. Therefore, it is ensured that the chain 30 is wound around ¼ or more of a circumference of each of the tie bar nut side sprockets 29, and it is not particularly necessary to provide an idler sprocket or the like in the mold clamping housing 11. Since the mold thickness adjusting motor 34 constituting the rotation drive unit is provided on a side of the mold clamping housing 11, the mold thickness adjusting motor 34 does not protrude from a bottom surface of the mold clamping housing 11. Therefore, the mold thickness adjusting motor 34 does not affect a machine length of the injection molding machine 1.
<Modification of Mold Thickness Adjusting Device>
The rotation drive unit that drives the drive target tie bar nut 27a can be modified as shown in
Although it has been described that one drive target. tie bar nut 27a is provided, the number of the drive target tie bar nuts 27a may be two or more as shown in
<Modification of Mold Clamping Device>
The mold clamping device 3 according to the present illustrative embodiment is provided with four tie bars 12, but the present disclosure can be similarly implemented with three tie bars, five or more tie bars. Regardless of the number of the tie bars 12, one or more of the tie bar nuts 27 provided on the tie bars 12 may be set as the drive target tie bar nut 27a, and the drive target tie bar nut 27a may be rotated by the rotation drive unit.
Comparative Example
The inventors of the present application have designed a mold clamping device 50 and a mold thickness adjusting device 51 shown in
In a design of this comparative example, the chain 57 is driven by a predetermined drive unit as in the related art without directly rotating the tie bar nuts 27. That is, the mold thickness adjusting motor 59 and a motor side sprocket 60 are used as the drive unit. However, the motor side sprocket 60 does not drive the tie bar nuts 27, but drives the chain 57 by the chain being wound therearound.
In the design, the same conditions as those in the illustrative embodiment of the present disclosure are imposed. That is, the mold thickness adjusting motor 59 serving as the drive unit is provided on a side of the mold clamping housing 11 so as not to affect a machine length, the large pulley 16 is provided at a central portion of the mold clamping housing 11, so that members constituting the mold thickness adjusting device 51 are not disposed around the large pulley 16, and the chain 57 is wound around ¼ or more of a circumference of each of the tie bar nut side sprockets 55.
As a result of these design conditions being imposed, in the mold thickness adjusting device 51 according to the comparative example, it is necessary to provide two idler sprockets 62, 63 in addition to a tension adjusting member 61. In this case, a large force as a resultant force acts on the idler sprockets 62, 63 due to a tension of the chain 57, so that there is a high possibility that bolts that pivotally support the idler sprockets 62, 63 will be damaged. In particular, it can be said that the chain 57 is wound around ¼ or more of a circumference of the idler sprocket 62, so that the resultant force is large and the possibility of damage of the bolt is high.
Compared to such a comparative example, the mold clamping device 3 and the mold thickness adjusting device 25 according to the present illustrative embodiment are superior without a risk of damage to the members.
Here, the present disclosure is not limited to the above-described illustrative embodiment, and modifications can be made without departing from the scope of the present disclosure. A plurality of examples described above can be implemented in combination as appropriate.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-156099 | Sep 2020 | JP | national |
