Patent Description:
A mold clamping device provided in an injection molding machine includes a fixed platen and a movable platen that opens and closes a mold with respect to the fixed platen, see for example document <CIT> or <CIT>. In an injection molding machine including a rotary platen for rotating a mold, the rotary platen is provided on a mold platen of a fixed platen and a movable platen, and as described in Patent Literature <NUM>, for example, the rotary platen is often provided on the movable platen. The rotary platen is provided to face the movable platen so as to rotate. Then, a plurality of molds, that is, rotary-side molds are attached. When the molds are clamped, one of the plurality of rotary-side molds is clamped with a fixed-side mold attached to the fixed platen. When a rotation position of the rotary platen is changed and the molds are clamped, another rotary-side mold is clamped with the fixed-side mold.

The mold platen is provided with a metal plate-form member, that is, a wear plate provided with a solid lubricant. This is to reduce friction when the rotary platen rotates relative to the mold platen in a slidable manner. This is because, although there is a type of rotary platen that rotates in a non-contact manner with a slight gap between the rotary platen and the mold platen without sliding against the mold platen, even such a rotary platen is required to be prepared for a case of sliding in contact with the mold platen.

When the rotary platen rotates, a relative speed between each part of the wear plate and the rotary platen is proportional to a distance from a rotation center. The relative speed is greatest at a position farthest from the rotation center. In this case, a sliding speed of the wear plate is maximized at the position farthest from the rotation center. The wear plate has an allowable sliding speed, and cannot be slid beyond this speed. In order to increase production efficiency, it is desirable to shorten a molding cycle by increasing a rotation speed of the rotary platen, but there is a problem in that it is difficult to increase the speed due to a restriction on the allowable sliding speed of the wear plate.

In view of the above problems, an object of the present disclosure is to provide a rotary platen that can be rotated at a high speed.

Other problems and novel features will become apparent from description of the present description and the accompanying drawings.

The present inventors have found that the above problems can be solved by adopting the configuration as defined in claim <NUM>.

According to the present disclosure, it is possible to provide a rotary platen that can be rotated at a high speed, a mold clamping device including the rotary platen, and an injection molding machine.

Hereinafter, specific illustrative embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following illustrative embodiments. In order to clarify the description, the following description and the drawings are simplified as appropriate. 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.

The present illustrative embodiment will be described.

A rotary platen according to an illustrative embodiment of present invention is a rotary platen that is disposed to face a mold platen, the rotary platen being provided to be rotatable with respect to the mold platen, and a mold being attachable to the rotary platen,.

A mold clamping device according to an illustrative embodiment of the present invention includes:.

An injection molding machine according to an illustrative embodiment of the present invention includes:.

As shown in <FIG>, an injection molding machine <NUM> according to the present illustrative embodiment includes a mold clamping device <NUM> for clamping a mold, an injection device <NUM> for melting and injecting an injection material, and a rotary platen <NUM> provided on the mold clamping device <NUM>.

The mold clamping device <NUM> includes a fixed platen <NUM> fixed on a bed B, a mold clamping housing <NUM> that slides on the bed B, and a movable platen <NUM> that also slides on the bed B. The fixed platen <NUM> and the mold clamping housing <NUM> are coupled by a plurality of, for example, four tie bars <NUM>, <NUM>. The movable platen <NUM> is slidable between the fixed platen <NUM> and the mold clamping housing <NUM>. A mold clamping mechanism <NUM> is provided between the mold clamping housing <NUM> and the movable platen <NUM>. The mold clamping mechanism <NUM> may be implemented by a direct pressure type mold clamping mechanism, that is, a mold clamping cylinder. In the present illustrative embodiment, the mold clamping mechanism <NUM> is implemented by a toggle mechanism.

As will be described in detail later, the rotary platen <NUM> according to the present illustrative embodiment is provided on the movable platen <NUM>. The fixed platen <NUM> is provided with a fixed-side mold <NUM>. The rotary platen <NUM> is provided with two rotary-side molds <NUM>, <NUM>. In <FIG>, the two rotary-side molds <NUM>, <NUM> attached to the rotary platen <NUM> are provided on a front side and a back side of the paper surface, and are shown in an overlapping manner. One of the two rotary-side molds <NUM>, <NUM> is aligned with the fixed-side mold <NUM> according to a rotation position of the rotary platen <NUM>. When the mold clamping mechanism <NUM> is driven, the fixed-side mold <NUM> and one rotary-side mold <NUM> aligned therewith are opened and closed.

The injection device <NUM> includes a heating cylinder <NUM>, a screw <NUM> inserted in the heating cylinder <NUM>, and a screw driving device <NUM> configured to drive the screw <NUM>. A hopper <NUM> is provided in the vicinity of a rear end portion of the heating cylinder <NUM>. An injection nozzle <NUM> is provided at a tip end of the heating cylinder <NUM>.

The rotary platen <NUM> is provided on the movable platen <NUM> as described above. <FIG> shows the rotary platen <NUM> and the movable platen <NUM> when viewed from a direction perpendicular to the rotary platen <NUM>. The rotary platen <NUM> rotates smoothly with respect to the movable platen <NUM>. A rotary platen driving mechanism <NUM> is provided above the movable platen <NUM>. A pulley <NUM> having a diameter slightly larger than that of the rotary platen <NUM> is fixed to the rotary platen <NUM>. As shown in <FIG>, a belt <NUM> is wound around the pulley <NUM> and the rotary platen driving mechanism <NUM>. When the rotary platen driving mechanism <NUM> is driven, the pulley <NUM> and the rotary platen <NUM> rotate integrally.

<FIG> shows the movable platen <NUM> with the rotary platen <NUM> (see <FIG>) removed. Four corners of the movable platen <NUM> are cut out to allow the tie bars <NUM>, <NUM>. to pass through. A circular table portion <NUM> having a large diameter is formed on a surface of the movable platen <NUM> on which the rotary platen <NUM> (see <FIG>) is placed, that is, on a facing surface. The circular table portion <NUM> is provided with a plate-form member for friction reduction, that is, a wear plate <NUM> provided with a solid lubricant. In the present illustrative embodiment, the wear plate <NUM> is characterized by an upper surface shape thereof, that is, a contour shape, which will be explained in detail later. The movable platen <NUM> and the wear plate <NUM> have a plurality of ejector rod holes <NUM>, <NUM>,. for protruding ejector rods.

In the illustrative embodiment of the present invention, of the movable platen and the rotary platen, the other platen on which the plate-form member is not provided has a base portion on a surface facing the one platen on which the plate-form member is provided. An upper surface of the base portion serves as a pressure receiving surface that comes into close contact with the plate-form member and receives a mold clamping force during mold clamping. It is preferable that a contour shape of the base portion is non-circular.

<FIG> shows the rotary platen <NUM> viewed from a mounting surface of the rotary-side molds <NUM> and <NUM>. The rotary-side molds <NUM> and <NUM> are indicated by two-dot chain lines. On a back surface side of the rotary platen <NUM>, that is, on a facing surface facing the movable platen <NUM> (see <FIG>), a base portion <NUM> slightly rising from the facing surface is formed. The base portion <NUM> is indicated by a dotted line. An upper surface of the base portion <NUM> serves as the pressure receiving surface that comes into close contact with the wear plate <NUM> (see <FIG>) and receives a mold clamping force during mold clamping. Similar to the wear plate <NUM>, the base portion <NUM> is also characterized by a contour shape, which will be explained in detail later. The rotary platen <NUM> also has a plurality of ejector rod holes <NUM>, <NUM>,. for protruding the ejector rods.

<FIG> is a sectional view of the movable platen <NUM> and the rotary platen <NUM> viewed from the side. The movable platen <NUM> and the rotary platen <NUM> are connected via a cross roller ring <NUM> which is a bearing component having a special shape. As shown in <FIG>, the cross roller ring <NUM> has a ring shape as a whole. The cross roller ring <NUM> includes an outer ring 36a, a pair of inner rings 36b, 36b, and a large number of rollers 36c, 36c,. interposed therebetween. The rollers 36c, 36c,. have a cylindrical shape and roll between the outer ring 36a and the pair of inner rings 36b, 36b. Therefore, in the cross roller ring <NUM>, the pair of inner rings 36b, 36b rotate smoothly relative to the outer ring 36a.

As shown in <FIG>, the pair of inner rings 36b, 36b of the cross roller ring <NUM> are fixed to the circular table portion <NUM> of the movable platen <NUM> by a pressing member <NUM>. The rotary platen <NUM> and the pulley <NUM> are fixed to the outer ring 36a of the cross roller ring <NUM>. That is, the rotary platen <NUM> is provided on the movable platen <NUM> via the cross roller ring <NUM>. As a result, the rotary platen <NUM> smoothly rotates relative to the movable platen <NUM>.

In the present illustrative embodiment, a gap is formed between the wear plate <NUM> provided on the movable platen <NUM> and the base portion <NUM> formed on the rotary platen <NUM>. That is, when the rotary platen <NUM> according to the present illustrative embodiment rotates, the wear plate <NUM> and the base portion <NUM> hardly come into contact with each other. That is, sliding hardly occurs. Although the gap is shown in an emphasized manner in <FIG>, the gap is actually small. Therefore, the base portion <NUM> and the wear plate <NUM> are brought into close contact with each other by a mold clamping force during mold clamping, and the mold clamping force is received by the movable platen <NUM>. When the rotation position of the rotary platen <NUM> is at a position where the mold can be clamped, the ejector rod holes <NUM>, <NUM>,. of the movable platen <NUM> and the ejector rod holes <NUM>, <NUM>,. of the rotary platen <NUM> are aligned.

In the illustrative embodiment of the present invention, the plate-form member is preferably formed of a material having a hardness lower than that of the base portion. The plate-form member is preferably made of a metal plate with a solid lubricant.

The wear plate <NUM> (see <FIG>) provided on the movable platen <NUM> is made of an alloy having a hardness lower than that of a metal forming the rotary platen <NUM>. In the wear plate <NUM>, a solid lubricant mainly composed of graphite is uniformly dispersed. The wear plate <NUM> is formed by sintering. The wear plate <NUM> in the present illustrative embodiment is characterized in that the contour shape is non-circular as shown in <FIG>. Specifically, the wear plate <NUM> has a circular shape with a small diameter at the center and a flat shape extending in a radial direction at both ends. The contour shape of the base portion <NUM> (see <FIG>) formed on the rotary platen <NUM> also substantially matches the contour shape of the wear plate <NUM>. That is, the base portion <NUM> has a flat shape.

In the illustrative embodiment of the present invention, it is preferable that each of the plurality of molds attached to the rotary platen is at least partially overlapped with the plate-form member when viewed from a direction perpendicular to the rotary platen.

As described above, at the time of mold clamping, the wear plate <NUM> and the base portion <NUM> come into contact with each other. Accordingly, the mold clamping force is received by the movable platen <NUM>. As shown in <FIG>, all of the rotary-side molds <NUM> and <NUM> partially overlap with the base portion <NUM>. That is, at the time of mold clamping, a part of the rotary-side molds <NUM>, <NUM> overlaps with the wear plate <NUM> (see <FIG>). As a result, the mold clamping force appropriately acts on the rotary-side molds <NUM>, <NUM>.

In the present illustrative embodiment, both of the wear plate <NUM> and the base portion <NUM> have a flat contour shape, and because they are formed in such a shape, the rotary platen <NUM> can be rotated at a high speed. This will be explained step by step.

In the illustrative embodiment of the present invention, a shape of an overlapping portion where the plate-form member and the base portion appear to overlap each other when projected from the direction perpendicular to the rotary platen may change according to the rotation position of the rotary platen, and
it is preferable that a maximum overlap radius is smaller when an angular speed of the rotary platen is the maximum than that when the angular speed is zero, the maximum overlap radius being a distance from the rotation center of the rotary platen to a position farthest from the rotation center of the overlapping portion.

Preferably, the shape of the overlapping portion is substantially the same as the contour shape of the plate-form member at the time of mold clamping.

When projected from the direction perpendicular to the rotary platen <NUM> (see <FIG>), the wear plate <NUM> of the movable platen <NUM> (see <FIG>) and the base portion <NUM> of the rotary platen <NUM> overlap each other, that is, the overlapping portion is formed. The shape of the overlapping portion changes according to the rotation position of the rotary platen <NUM>. <FIG> shows an overlapping portion <NUM> of the wear plate <NUM> and the base portion <NUM> when the rotary platen <NUM> is at a first rotation position. The shape of the overlapping portion <NUM> is substantially the same as that of the wear plate <NUM> and the base portion <NUM>. Therefore, as described above, at the time of mold clamping, the mold clamping force acts on the entire wear plate <NUM> and the base portion <NUM>.

When rotating the rotary platen <NUM> (see <FIG>) from the first rotation position, that is, a rotation position of <NUM> degree, to a second rotation position, that is, a rotation position of <NUM> degrees, changes in the overlapping portion <NUM> at each rotation position are considered. When the rotation of the rotary platen <NUM> is started and a rotation angle reaches <NUM> degrees, the overlapping portion <NUM> changes as shown in <FIG>. Next, when the rotation angle reaches <NUM> degrees, <NUM> degrees, and <NUM> degrees, the overlapping portion <NUM> changes as shown in <FIG>, and <FIG>, respectively.

As described above, in the injection molding machine <NUM> (see <FIG>) according to the present illustrative embodiment, the wear plate <NUM> and the base portion <NUM> hardly come into contact with each other when the rotary platen <NUM> (see <FIG>) rotates. However, at the time of designing the injection molding machine <NUM>, it is assumed that the wear plate <NUM> and the base portion <NUM> will come into contact with each other and slide during the rotation. The wear plate <NUM> has a maximum value of allowed sliding speed, that is, an allowable sliding speed. In this case, it is necessary to design so as not to exceed the allowable sliding speed. When the wear plate <NUM> and the base portion <NUM> slide during the rotation, it is the overlapping portion <NUM> (see <FIG>) that slides. The sliding speed differs depending on each portion of the overlapping portion <NUM>, and is maximum at a portion farthest from the rotation center <NUM>. This is because the sliding speed is given by the product of the angular speed of the rotation and a distance from the rotation center <NUM>.

When the rotation angle is <NUM> degree, that is, when the rotary platen <NUM> (see <FIG>) is at the first rotation position, as shown in <FIG>, the portion farthest from the rotation center <NUM> in the overlapping portion <NUM> is denoted by a reference numeral <NUM>, and the sliding speed becomes the maximum at this portion. When the rotation position is <NUM> degrees, <NUM> degrees, <NUM> degrees, and <NUM> degrees, as shown in <FIG>, the sliding speed becomes the maximum at portions denoted by reference numerals <NUM>, <NUM>, <NUM>, and <NUM>, respectively.

The graph of <FIG> shows changes in an angular speed <NUM> of the rotary platen <NUM> and a maximum sliding speed <NUM> in the overlapping portion <NUM> when the rotary platen <NUM> (see <FIG>) is rotated from the first rotation position to the second rotation position. Further, for reference, changes in a tip end speed <NUM> in a tip end portion <NUM> of the base portion <NUM> in <FIG> are shown by the graph. The angular speed <NUM> of the rotary platen <NUM> is zero when the rotation angle is <NUM> degree, that is, at the first rotation position, and increases as the rotation angle increases from <NUM> degrees to <NUM> degrees. The angular speed <NUM> is maximum when the rotation angle is <NUM> degrees, then decreases, and becomes zero when the rotation angle reaches <NUM> degrees, that is, at the second rotation position. The tip end speed <NUM> (see <FIG>) in the tip end portion <NUM> (see <FIG>) of the base portion <NUM> changes similarly to the angular speed <NUM>. That is, the tip end speed <NUM> is zero when the rotation angle is <NUM> degree, increases as the rotation angle increases, reaches the maximum when the rotation angle is <NUM> degrees, and then decreases to zero when the rotation angle is <NUM> degrees.

On the other hand, the maximum sliding speed <NUM> (see <FIG>) changes as follows. First, the maximum sliding speed <NUM> is zero when the rotation angle is <NUM> degree, and increases similarly to the tip end speed <NUM> until the rotation angle reaches <NUM> degrees. However, when the rotation angle exceeds <NUM> degrees, the rate of increase in the maximum sliding speed <NUM> decreases. That is, the rate of increase is smaller than that of the tip end speed <NUM>. When the rotation angle is <NUM> degrees, the maximum sliding speed <NUM> is maximum, but is only about <NUM>% of the tip end speed <NUM>. Thereafter, as the rotation angle increases, the maximum sliding speed <NUM> decreases and becomes zero when the rotation angle is <NUM> degrees.

The reason why the maximum sliding speed <NUM> is less likely to increase as described above is that the contour shapes of the wear plate <NUM> and the base portion <NUM> are flat. As can be understood from <FIG> and <FIG>, this is because a maximum overlap radius R, which is the distance from the rotation center <NUM> to the farthest portion (reference numerals <NUM> to <NUM>) in the overlapping portion <NUM>, is smaller when the angular speed <NUM> is maximum than when the angular speed <NUM> is zero.

As described above, the wear plate <NUM> has a predetermined allowable sliding speed, and cannot be allowed to slide beyond the speed. In the injection molding machine <NUM> (see <FIG>) according to the present illustrative embodiment, the maximum sliding speed <NUM> is less likely to increase. Thus, even if the rotary platen <NUM> is rotated at a high speed, the allowable sliding speed of the wear plate <NUM> is not exceeded. Therefore, the injection molding machine <NUM> according to the present illustrative embodiment can rotate the rotary platen <NUM> at a high speed.

Various modifications are possible for the injection molding machine <NUM> according to the present illustrative embodiment. For example, the wear plate <NUM> (see <FIG>) and the base portion <NUM> (see <FIG>) may be deformed. <FIG> show flat wear plates 30A to 30C, respectively. In each of the wear plates 30A to 30C, a distance from the rotation center <NUM> is longer in a left-right direction, and is shorter in an upper-lower direction. Therefore, when the base portion <NUM> is also formed into a flat shape like the wear plates 30A to 30C, the maximum sliding speed is less likely to increase, and the rotation speed of the rotary platen <NUM> (see <FIG>) can be increased.

Each of the wear plates <NUM>, 30A to 30C shown in <FIG> and <FIG> has a shape elongated in a lateral direction. The reason for the flat shape elongated in the lateral direction as described above is that the rotary-side molds <NUM>, <NUM> are arranged horizontally as shown in <FIG>, and this allows the mold clamping force to act on the rotary-side molds <NUM>, <NUM> during mold clamping. On the other hand, in a case where the rotary-side molds <NUM>, <NUM> are arranged vertically, the wear plate 30D may be formed to be long in a vertical direction as shown in <FIG>. As a result, the mold clamping force reliably acts on the rotary-side molds <NUM>, <NUM>.

As shown in <FIG> and <FIG>, the plate-form member, that is, wear plates 30E and 30F may include a plurality of divided piece plates <NUM>, <NUM>,. , and <NUM>. When the wear plate includes the plurality of piece plates <NUM>, <NUM>,. , and <NUM>, if the contour shape of the wear plates 30E, 30F is also non-circular as a whole, the rotation speed of the rotary platen <NUM> (see <FIG>) can be increased.

In the present illustrative embodiment, the wear plate <NUM> (see <FIG>) is provided on the movable platen <NUM>, and the base portion <NUM> (see <FIG>) is formed on the rotary platen <NUM>. However, the wear plate <NUM> may be provided on the rotary platen <NUM>, and the base portion <NUM> may be formed on the movable platen <NUM>.

As described above, the rotary platen according to an illustrative embodiment of present invention is a rotary platen that is disposed to face a mold platen, is provided to be rotatable with respect to the mold platen, and is configured such that a mold is attached thereto,.

In this case, the plate-form member is preferably formed of a material having a hardness lower than that of the mold platen.

The plate-form member is preferably made of a metal plate with a solid lubricant.

In the present illustrative embodiment, it has been described that the wear plate <NUM> and the base portion <NUM> hardly come into contact with each other during the rotation of the rotary platen <NUM> (see <FIG>), and therefore, hardly slide. However, the wear plate <NUM> and the base portion <NUM> may slide during the rotation.

Although the invention made by the present inventors is specifically described based on the illustrative embodiment, it is needless to say that the present invention is not limited to the illustrative embodiment described above, and various modifications can be made without departing from the scope of the invention. The plurality of examples described above may be appropriately combined.

Claim 1:
A mold clamping device (<NUM>) comprising:
a fixed platen (<NUM>), a first mold (<NUM>) being attachable to the fixed platen (<NUM>);
a movable platen (<NUM>) configured to open and close molds (<NUM>, <NUM>) with respect to the fixed platen (<NUM>); and
a rotary platen (<NUM>) disposed to face the movable platen (<NUM>), the rotary platen (<NUM>) being provided to be rotatable with respect to the movable platen (<NUM>), and a second mold (<NUM>) being attachable to the rotary platen (<NUM>),
wherein a plate-form member (<NUM>) is provided on a surface of one platen of the movable platen (<NUM>) and the rotary platen (<NUM>) that faces the other platen, and
wherein a contour shape of the plate-form member (<NUM>) is non-circular, characterized in that
a base portion (<NUM>) is formed on a surface of the other platen that faces the one platen,
wherein an upper surface of the base portion (<NUM>) serves as a pressure receiving surface that is configured to come into close contact with the plate-form member (<NUM>) and receive a mold clamping force during mold clamping, and
wherein a contour shape of the base portion (<NUM>) is non-circular.