Fixed platen of injection molding machine

Abstract

A fixed platen of an injection molding machine is provided with a first leg protruding at a substantially central portion of a lower part and secured to a base frame and second legs protruding left and right. Each of the second legs is provided with a thin portion thinner than the fixed platen. Thus, a deformation difference between the upper and lower sides of the fixed platen caused during nozzle touch operation or when the fixed platen is subjected to a mold clamping force can be reduced.

Claims

1. A fixed platen of an injection molding machine, secured to a base frame and capable of supporting a fixed mold, the fixed platen comprising: a mold mounting surface capable of being fitted with a mold; a tie-rod insertion part at a corner through which a tie rod is configured to be passed for fixation; a first leg protruding at a substantially central portion of a lower part and secured to the base frame; and a second leg protruding near the tie-rod insertion part at the lower part and secured to the base frame, wherein the second leg comprises a thin portion thinner than the fixed platen along the axis of the tie rod and respective thickness-direction centers of the thin portion and the fixed platen are substantially coincident along the axis of the tie rod.

2. The fixed platen of an injection molding machine according to claim 1, wherein the first leg extends in an opposite direction to the mold mounting surface and is secured to the base frame.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other objects and features of the present invention will be obvious from the ensuing description of embodiments with reference to the accompanying drawings, in which:

(2) FIG. 1 is a front view of a fixed platen according to a first embodiment of the present invention;

(3) FIG. 2 is a side view of the fixed platen according to the first embodiment of the present invention;

(4) FIG. 3 shows a deformed shape of the fixed platen according to the embodiment of the present invention;

(5) FIG. 4 is a side view of a fixed platen according to a second embodiment of the present invention;

(6) FIG. 5 is a schematic view for illustrating the configuration of a conventional injection molding machine;

(7) FIG. 6 is a perspective view showing a base frame and a fixed platen of the injection molding machine;

(8) FIG. 7 shows a deformed shape of a fixed platen of a conventional injection molding machine;

(9) FIG. 8 shows an example of fixation of the fixed platen of the conventional injection molding machine; and

(10) FIG. 9 shows an example of fixation of a fixed platen of a conventional injection molding machine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

(11) A first embodiment of the present invention will now be described with reference to the accompanying drawings. FIG. 1 is a front view of a fixed platen 5 according to the present embodiment taken from the opposite side to an injection unit 2 when it is mounted in place. FIG. 2 is a side view of the fixed platen 5. The fixed platen 5 of the present embodiment comprises a plurality of legs. In the front view of FIG. 1, a first leg 21 is provided at a substantially central portion with respect to the horizontal direction, and two second legs 22 protrude individually from the respective lower parts of left and right tie-rod insertion parts 24. As shown in FIG. 2, moreover, each of the left and right second legs 22 is formed with a thin portion 23 made thinner along the axis of each tie rod near a central portion between the fixed platen 5 and a base frame 4 with respect to the vertical direction. The thin portion 23 is located so that its position along the axis of each tie rod is at the substantially central portion. Thus, the respective thickness-direction centers of the fixed platen 5 and the thin portion 23 are substantially coincident. The front and rear surfaces of the thin portion 23 are formed substantially parallel to a mold mounting portion of the fixed platen 5.

(12) Thus, the fixed platen 5 is secured to the base frame 4 at three points, the first leg 21 in the center and the left and right second legs 22. When the fixed platen 5 is subjected to a nozzle touch force, therefore, its vertical falling and horizontal rotation can be suppressed. In some of the conventional techniques described above, the fixed platen 5 is secured by only one of the first and second legs 21 and 22. With this configuration, the fixed platen 5 may possibly be caused to fall down or horizontally rotate by the nozzle touch force.

(13) Since the first leg 21 is provided at the substantially central portion that is less deformable, the degree of deformation is not influenced if the strength of the leg is increased. In the present embodiment, therefore, the thickness of the central first leg 21 is made substantially equal to that of the fixed platen 5, and only the left and right second legs 22 are provided with the thin portion 23 each. With this configuration, moderate deformation can be caused near the tie-rod insertion parts 24 while preventing falling and horizontal rotation by the nozzle touch force.

(14) FIG. 3 shows a deformed shape of the fixed platen 5 of the present embodiment subjected to a force. Provided with the thin portion 23, each of the left and right second legs 22 can also be moderately deformed below the fixed platen 5, so that a deformation difference between the upper and lower parts of the fixed platen 5 can be reduced.

Second Embodiment

(15) FIG. 4 is a side view of a fixed platen 5 according to a second embodiment of the present invention. In the present embodiment, a first leg 21 provided at a substantially central portion with respect to the horizontal direction in a front view is secured to a base frame 4 so as to project on the opposite side to a mold mounting surface of the fixed platen 5. Thus, the space between first and second legs 21 and 22 along an injection axis can be widened, so that the degree of fall of the fixed platen 5 caused by a nozzle touch force generated during nozzle touch operation can be reduced.

(16) In these embodiments, the first leg 21 is located at the central portion of the fixed platen 5. However, the position of the first leg 21 may be somewhat shifted horizontally with the same effect. In these embodiments, moreover, the second legs 22 are located just below the tie-rod insertion parts 24. However, regions near the tie-rod insertion parts 24 can be moderately deformed despite some horizontal shift or misalignment only if the second legs 22 are located near the tie-rod insertion parts 24.

(17) In these embodiments, furthermore, the second legs 22 are located so that the respective thickness-direction centers of the fixed platen 5 and the thin portion 23 are substantially coincident. Although deformation of the upper and lower parts of the fixed platen 5 is better balanced if the thickness-direction centers of the fixed platen 5 and the thin portion 23 are substantially coincident, the location of the second legs 22 may be somewhat shifted longitudinally along the tie rods.

(18) In the embodiments described above, the front and rear surfaces of the thin portion 23 of each second leg 22 are formed substantially parallel to the mold mounting portion of the fixed platen 5. If the thin portion 23 is formed in this manner, the regions near the tie-rod insertion parts 24 are easily deformable. Alternatively, however, the front and rear surfaces of the thin portion 23 may be formed obliquely or curved, not flat.

(19) Alternatively, moreover, vertical posts that connect the upper and lower main pipes (upper main pipes 32 and lower main pipes 33) may be provided at the spots where the first and second legs 21 and 22 of the fixed platen 5 are secured. Thus, the fixed platen 5 can be better kept from falling down.