JPS5939533A - Direct pressure type force clamping device for injection molding machine or the like - Google Patents

Abstract

PURPOSE:To provide the titled device capable of enhancing the precision of degree of parallelness of a platen in correspondence with precision molding and capable of maintaining the correct parallelness for a long period of time, wherein oil grooves for exerting an oil pressure are provided at the bearing part for a rod. CONSTITUTION:Balancing grooves 20 as oil grooves are provided at the bearing part 5 for the rod 3 of a force clamping ram 2, and a plurality of annular V- shaped grooves 26 as oil grooves are provided at the outside peripheral surface of the piston 4 of the ram 2. Though a cantilever distance is enlarged as the rod 3 is moved forward, the oil pressure in the balancing grooes 20... serves for automatic centering in response to a rise in side pressure, and the degree of horizontalness of the rod 3 itself is maintained to be correct. The oil pressure is also exerted in the interior of the V-shaped grooves 26... of the piston 4 concurrently with high-pressure force clamping, and oil pressure balance is achieved not only on the side of the rod 3 but also on the side of the piston 4, so that the degree of parallelness of the platen is maintained.

Description

Detailed Description of the Invention (1) Technical Field of the Invention The present invention relates to a mold clamping device for an injection molding machine or a die casting machine, and more particularly to a structure for ensuring parallelism of platens in a direct pressure mold clamping device. It is something.

(2) Conventional technology and its problems Traditionally, direct pressure type mold clamping devices such as injection molding machines have a mold clamping cylinder placed horizontally on a bed, and the mold clamping cylinder is moved in the forward and backward direction through a tight A movable side platen and a fixed side platen are arranged.

The rod of the mold clamping cylinder is provided with a movable platen, and the bearing portion of the rod is constituted by a bushing having a clearance of at least about 30 microns to allow the rod to move forward and backward. Therefore, the weight of the movable platen and the mold attached to it causes the rod to be eccentric within the bearing clearance range, and at the same time causes the tie bar to bend, which in turn causes the platen to become out of parallelism. It was something. If the parallelism of the platen is out of alignment, the guide pins of the mold will be subject to uneven loads and wear out, and the molds will not be properly aligned, which will shorten the life of the mold. I ended up losing it.

In order to overcome the above drawbacks, the tie bars have been made large in diameter to minimize deflection, or a support plate has been interposed between the lower surface of the movable platen and the bed. In the former case, there is a limit to increasing the diameter of the tie bar.

When the tie bar is made larger in diameter, the mold mounting surface of the platen is narrowed by the larger diameter. For this reason, enlarging the area of the platen is undesirable because the overall load increases. The diameter of the tie bar could only be increased within a range not restricted by the mold mounting surface. Unfortunately, in the latter case, it is necessary to ensure the parallelism of three points: the rod of the mold clamping cylinder, the fixed platen, and the movable platen with the support plate. Since the bed of the main body is not necessarily horizontal and there is a clearance in the bearing part, the parallelism of the three points mentioned above cannot be achieved strictly from the viewpoint of machining. Even if it is assumed that the parallelism is accurately achieved, firstly, the support plate is affected by the heat of the molding cycle, resulting in dimensional errors. Second, the support plate has a clearance necessary for movement between it and the vent, but at the same time it wears due to metal contact with the bed, so adjust it according to the frequency of use while allowing for the above clearance error. It must be. Thirdly, the support plate needed to be finely adjusted every time the mold was replaced in response to the amount of mold M.

In view of the above-mentioned circumstances, a device in which a rolling bearing is provided on the lower surface of the movable platen in place of the support plate has been provided. This thing has a predetermined clearance necessary for rolling between it and the bed.

Although this clearance is smaller than the clearance of the support plate, it is unavoidable that dust and the like are mixed in, and rattling occurs due to wear caused by long-term use. In any case, the parallelism of the platen is limited to a maximum of 50 microns and cannot be guaranteed over a long period of time. Therefore, at present, the molds are matched on the assumption that there is an error in the parallelism of the platen.

By the way, with the development of engineering plastics in modern times, precision on the order of microns has been required in injection molding.

In order to meet this demand, the mold must have an absolute condition that the dividing surfaces match exactly. No matter how precisely the mold is finished, if there is an error in mold matching, molding on the micron order is impossible.

In this sense, the parallelism of the conventional platen mentioned above is limited to 50 microns at most, so it cannot be applied to molds for precision parts that require accuracy of 10 microns or less. .

(3) Purpose of the Invention The present invention has been provided in view of the above-mentioned circumstances, and is capable of increasing the precision of the parallelism of the platen in response to precision molding, and ensuring a consistent parallelism over a long period of time. The purpose of this is to ensure that the degree of

(4) Features of the Invention The feature of the present invention is that the oil groove in which pressure oil acts on the bearing portion of the rod is provided throughout.

Hereinafter, the present invention will be explained based on the drawings.

(5) One embodiment of the invention The drawings show one embodiment of the mold clamping device for an injection molding machine or the like according to the present invention, FIG. 1 is a schematic cutaway diagram of the same part showing the mold opening, and FIG. 2 is a partially cutaway schematic diagram showing the mold opening. FIG. 3 is an enlarged sectional view of the same essential part. The drawing shows a booster ram type implementation.

In the figure, 1 is the mold clamping cylinder, 2 is the mold clamping ram, 3 is the rod of the mold clamping ram 2, 4 is the piston of the mold clamping ram 2, and 5 is the rod 3
bearing part, 6 is the 7 flange of the bearing part 5, γ huff refill valve, 8 is the booster ram, 9.10.11 is the chamber where oil acts, 12 is the movable side 1 platen, 13 is attached to the movable side platen 12. 14 is a stationary platen, 1
5 is a mold attached to the fixed side planar y14, and 16 is a tie bar. This horizontal structure direct pressure mold clamping device is well known.

The bearing portion 5 is provided with a balancing groove 20 as an oil groove. A large number of balancing grooves 20 are provided in an annular shape surrounding the rod 3 on the inner circumferential surface of the bearing portion 5, and are formed in a V-shaped cross section with an appropriate gap.

A pressure port 21 that communicates with a hydraulic power source 22 is provided at the axial center of the bearing portion 5, and a boat 23 that communicates with a drain tank 24 is provided at the axial tip side, and a boat 23 that communicates with a drain tank 24 is provided at the axial tip side. is sealed with dust roller 25. The piston 4 of the mold clamping ram 2 has a large number of annular V-shaped grooves 26 as oil grooves on its outer circumferential surface, and a ball bearing 27 as a rolling bearing on its inner circumferential surface. Similarly, the ball bearings 28 are provided in the hole portions of the movable platen 12, which are sliding portions with the tie bars 16.

Based on the above configuration, pressure oil is constantly supplied from the hydraulic power source 22 to each balancing groove 20 through the pressure port 21, and from the port 23 on the distal end to the drain tank 24 and the There is a slight leakage into chamber 11. Therefore, since the pressure oil acts on each balancing groove 20 . . . in the radial direction on average, the hydraulic pressure is balanced in the radial direction in each balancing groove 20 .

An oil film filled with pressure oil is formed in the clearance between the rod 3 and the bearing portion 5, so that the rod 3 slides in the axial direction almost under no load. Rod 3 is
The movable platen 12 and the mold 13 are supported in a cantilever by the rigidity of the large diameter, and the bearing part 5 is supported by the cantilever.
Since the lateral pressure is self-aligned, the movable platen 12 and the mold 13 maintain parallelism without eccentricity. Due to this hydraulic balance, the tie bar 16 is connected to the movable platen 12.
and is not receiving the load of the mold 13. Further, since the pressure oil is supplied and discharged independently of the mold clamping mechanism, the parallelism of the platen is ensured regardless of the mold opening/closing operation.

Next, when the mold is clamped, when hydraulic pressure is applied to the chamber 9 of the booster ram 8 in the mold closing region, the rod 3 immediately moves forward because the rod 3 is in a nearly unloaded state.

The ball bearings 28 of the movable four-rule platen 12 are guided by the tie bars 16 and move without being subjected to their own weight. The cantilever support distance of the rod 3 increases as it moves forward, but
Since the pressure oil in the balancing grooves 2o self-centers as the side pressure increases, the horizontality of the rod 3 itself is still accurately maintained. The rigidity of the rod 3 is such that it does not affect the parallelism between the movable platen 12 and the mold 13.

Therefore, the rod 3 always maintains the parallelism of the platen from the low-speed mold-closing region and the high-speed mold-closing region to the mold-closing protection region. The mold 13 of the movable platen 12 and the mold 15 of the stationary platen 14 are fitted with each other in accurate alignment. During this time, prefill valve 7
Oil is sucked into chamber 10 from.

Further, in the high-pressure mold clamping region, the prefill valve γ is closed, and the pressure oil acts on the mold clamping ram 2 to generate a predetermined high-pressure mold clamping force. With high-pressure mold clamping, the V-shaped groove 2 of the piston 4
6... Hydraulic pressure will also act on the inside. the result,
Hydraulic balance will work not only on the rod 3 side but also on the piston 4 side, and the parallelism of the platen will be maintained at two locations.

When opening the mold, the prefill valve 7 opens and hydraulic pressure is applied to the chamber 11. Since hydraulic pressure is supplied to the V-shaped groove 26 of the piston 4 as well as the chamber 11, the piston 4 is maintained in hydraulic equilibrium. Therefore, the piston 4 and the rod 3 are in a nearly unloaded state, and since the bearing 27 is provided on the inner circumferential surface of the piston 4, the mold clamping ram 2 moves back in response to the hydraulic pressure and opens the mold. will be done. Of course, the parallelism of the platen continues to be maintained in the mold opening region.

(6) Another embodiment of the invention In the above embodiment, a V-shaped groove 2 is provided on the outer peripheral surface of the piston 4.
Although the V-shaped groove 26 has been described, a structure may be adopted in which the outer peripheral surface is sealed without providing the V-shaped groove 26.

Although the booster ram type was illustrated and explained in the above embodiment, it goes without saying that the present invention is not limited to this. As long as it is a direct pressure type mold clamping device consisting of a mold clamping cylinder, a platen, and a tie bar, it can also be implemented as an auxiliary cylinder type, a pressure increase cylinder type, etc., for example.

(7) Effect of invention According to the present invention, the following effects are achieved.

(b) Since the rod bearing part is provided with an annular oil groove in which pressure oil acts, the rod is supported horizontally through the oil film that forms in the clearance at the bearing part, and the rod's rigidity allows it to move easily on the movable side. It was possible to accurately maintain the levelness of the platen and mold. Since self-alignment works against the lateral pressure depending on the amount of advance and retreat of the rod, the parallelism of the platen can always be set uniformly. As a result, it is possible to maintain parallelism of about 10 microns or less, and it can be applied to molds for precision parts to enable precision molding.

(b) Since pressurized oil acts on the rod and the bearing, the rod is in a nearly no-load state, allowing high-speed opening and closing without backlash, and allows for slow-speed feeding with very low pressure.

In particular, in the conventional closed protection area, low-speed feeding was performed under a large load, but there is an advantage in that foreign object detection can be performed accurately by being able to perform slow-speed feeding with low pressure.

C→ Since the platen is cantilever-supported by the rigidity of the rod, the tie bar can be made thinner, and the entire surface of the mold can be enlarged.

2) Since there is no metal contact between the rod and the bearing, there is no wear even after long-term use, and the platen can maintain its parallelism without deviation over a long period of time. Furthermore, even if the weight of the mold changes, it is self-centering, so fine adjustments are not necessary.

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawings show an embodiment of a mold line device such as a creation molding machine according to the present invention, and FIG.
The figure is a schematic cutaway view of the same part showing the mold opening, and FIG. 3 is an enlarged sectional view of the same main part. DESCRIPTION OF SYMBOLS 1... Mold clamping cylinder, 2... Mold clamping ram, 3... Rod, 5... Rod bearing part, 12... Movable side platen, 14... Fixed side platen, 16...・Tie bar, 20.26...oil groove. Patent applicant Yoshi Yoshi, patent attorney representing Technoplus Co., Ltd. 1) Haru Yoshi

Claims (1)

[Claims] In a direct pressure type mold clamping device such as an injection molding machine, in which a movable platen is provided on the rod of the mold clamping cylinder, and the first movable platen opens and closes the mold to the fixed platen via a quiver, the above-mentioned rod A direct pressure type mold clamping device for an injection molding machine, etc., characterized in that a bearing part is provided with an annular oil groove in which pressure oil acts.