Machine Base With Hydraulic Controls for Injection Molding Machine

1. Field of the Invention

The present invention relates to hydraulic controls for injection molding machines, and in particular to arrangements of hydraulic controls and hydraulic components on the base of an injection molding machine.

2. Description of the Prior Art

Injection molding machines require a number of hydraulic control components for the operation of the die closing unit, injection unit or units, parts ejection device, core removing unit, etc. These hydraulic controls are normally arranged in accordance with design expedience or availability of mounting space. In a known machine base of this type, as disclosed in my U.S. Pat. No. 3,914,082, a number of hydraulic distributors are combined in a compact distributor block which is mounted in a horizontal position inside the forward compartment of the machine base, at a level situated below the level of hydraulic fluid in the adjacent hydraulic fuel reservoir. The solenoid valves associated with the distributor block are attached to the underside of the distributors in a compact row. The oil filter for the hydraulic system, arranged in the return line, is likewise arranged below the fluid level of the reservoir.

In other prior art solutions, the various distributors are not combined in a single distributor block, but two or more groups of distributors are arranged at different locations on the machine base, in accordance with the position of the various machine components.

Among the shortcomings inherent to these prior art solutions are their lack of easy accessibility, poor cooling of the components, inadequate visibility of the components for visual inspection and monitoring, and frequently, poor placement of the adjustment knobs for the hydraulic controls. Lastly, the arrangement of a distributor system in several groups, or as a single block inside the machine base, is costly in terms of manufacture as well as in terms of servicing and replacement of components. For example, in the case of the distributor block situated below the fluid level, the latter has to be lowered, before the hydraulic controls components can be removed for inspection or replacement.

It is a primary objective of the present invention to eliminate at least some of the above-mentioned shortcomings by suggesting an improved arrangement of the hydraulic controls on an injection molding machine base.

The present invention proposes to attain the above objective by suggesting a machine base for an injection molding machine in which the distributors and associated solenoid valves are combined in a single distributor block assembly which is mounted on the outside of the rear longitudinal wall of a block-shaped machine base, with the main distributors for the die closing unit and injection unit, or units, positioned above the fluid level in the hydraulic fluid reservoir and the remaining distributors arranged in a compact row underneath them. It further suggests that the adjustment knobs for these control components be arranged on the outside of the front longitudinal wall of the machine base, where they are conveniently accessible to the machine operator.

The invention further suggests that the interior space of the block-shaped machine base be subdivided by a transverse wall into a rear compartment, serving as a hydraulic fluid reservoir, and a forward compartment situated underneath the die closing unit and accomodating the cooler for the hydraulic fluid. The distributor block assembly is thus mounted on the backside of this cooler compartment, while the control knobs are supported in the front longitudinal wall of the compartment, being connected to the various distributors by means of long control shafts reaching through the cooler compartment. These control shafts are preferably of the universal-joint type, thereby permitting spacing and location of the control knobs on the front longitudinal wall in an esthetically pleasing and convenient arrangement.

Besides being compact and easily accessible, this hydraulic controls arrangement has the further advantage that it is most suitable for adaption to different hydraulic controls requirements of various types of injection molding machines. For this purpose, the number of distributors in the distributor block assembly can be conveniently increased or decreased, in accordance with the building block system. Furthermore, because the hydraulic controls are arranged at the outside of the machine base, their cooling is improved, which in turn increases the longevity of the components. Still further advantages are realized with respect to the manufacture and assembly of these components, and especially with respect to inspection and servicing accessibility. Lastly, the suggested arrangement of the distributor block assembly means that the plungers of the distributor valves move horizontally and are not affected by gravity.

The distributor block assembly is preferably attached to the rear longitudinal wall of the machine base by means of an intermediate mounting bracket arranged between the upper distributors and the machine base wall. These upper distributors control the hydraulics of the die closing unit and of the injection unit, or units, and are therefore standard equipment for all injection molding machines. The remaining distributors and associated solenoids are simply mounted to the underside of these upper distributors.

The filter for the hydraulic fluid is preferably likewise mounted on the outside of the machine base, adjacent to the distributor block assembly, so as to be easily accessible for servicing.

Further special features and advantages of the invention will become apparent from the description following below, when taken together with the accompanying drawings which illustrate, by way of example, an embodiment of the invention, represented in the various figures as follows:

FIG. 1 shows a machine base for an injection molding machine, as seen from behind, with a hydraulic controls arrangement, as an embodiment of the invention;

FIG. 2 shows the machine base of FIG. 1 in an enlarged-scale plan view; and

FIG. 3 is a likewise enlarged partially cut front view of the machine base of FIG. 1.

In FIGS. 1-3 is illustrated a block-shaped base for an injection molding machine constructed of welded steel sheet. The inside of this rectangular structure is subdivided by a transverse wall 48 so as to create a hydraulic fluid reservoir 2 between the transverse wall 48 and the right-hand side wall 1" of the machine base, and a cooler compartment 47 between the transverse wall 48 and the left hand side wall 1'. Inside the -- partially open -- cooler compartment 47 is arranged a cooler 14 for the hydraulic fluid. The right-hand side wall 1" carries a hydraulic power unit consisting of an electric motor 5, mounted on the back side of wall 1" by means of a flange 6, and a hydraulic pump 4 projecting into the fluid reservoir 2 from a flanged socket 3 clamped against the inside of wall 1". The machine base itself is supported on its four corners by elastic supports 7.

This machine base is designed to carry a die closing unit (not shown), including a stationary die plate and a movable die plate, the stationary die plate being part of a stationary cylinder mount, for example. This die closing unit, including one or several injection units, is supported on the machine base at the mounting faces 42 and 43 (FIG. 2). The mounting face for the injection molding die on the stationary die plate would preferably be positioned in alignment with the left-hand side wall 1' of the machine base. The cooler unit 14 is mounted against the transverse wall 48, a fluid return outlet 15 leading from cooler 14 across the wall 48 into the reservoir 2.

On the rear longitudinal wall 1.sup.IV is mounted a distributor block assembly 8, 9, 10, and 11. This assembly consists essentially of a vertically arranged series of distributors 8, each carrying a control valve 9 with solenoids 10 and 11. For this purpose, the distributors 8 have an outer mounting face extending parallel to the rear longitudinal wall 1.sup.IV on which the control valve 9 is mounted. The valves 9 carry solenoids 9 and 10 on their longitudinal extremities, meaning that the valve plungers are oriented horizontally and are therefore not influenced by gravity. Only the upper distributors 8 which control the die closing unit and the injection unit, or units, are directly mounted against the base wall 1.sup.IV, using an intermediate mounting bracket, since the die closing and injection units can be considered standard components for all injection molding machines. The remaining distributors 8 are attached to the underside of the upper distributors, being carried by the latter. These additional distributors may control such machine components as the parts ejector device, core removing unit, and others.

The inlet and outlet lines 16 for the distributors 8 of the die closing unit and injection unit are arranged on the right-hand side of the distributor 8, (FIG. 2) while the corresponding lines for lower distributors 8 run in the opposite direction, and the lines of still further distributors may run through the wall 1.sup.IV to the inside of the machine base.

The upper distributors 8 are arranged just below the top surface of the machine base, defined by a top frame 26, meaning that they are located above the fluid level of the hydraulic fluid reservoir 2. On each side of the distributor block assembly, at about the level of the uppermost distributor 8, are further arranged horizontal cantilever arms 17 and 18 carrying the legs 19 and 20 of a vertically adjustable cooling controls assembly 27. These cooling controls include a series of vertical columns 30 and flow adjustment controls 28 and 29.

The distributor block assembly and the cooling controls assembly are thus positioned on the rear side, i.e. the side opposite the normal position of the machine operator. While the columns 30 of the cooling controls assembly are visible across the machine, adjustment access to the distributors 8 by the operator is accomplished by extending the adjustment controls horizontally across the cooler compartment 47 of the machine base to the outside of the front longitudinal wall 1'". Each distributor 8 has two throttle members, one for each flow direction of the hydraulic fluid, thereby permitting independent adjustment of the speed of the advancing and retracting motions of the various machine components. To each throttle member is connected a rotatable control shaft 25 extending across the free space of the cooler compartment 47, the shaft being supported in a bearing mounted in the front longitudinal wall 1'" of the base and carrying a knob 21, 22, etc. on its protruding end. Depending on the horizontal and vertical spacing of the various throttle members in the distributor block assembly, some or all of the control shafts 25 may be provided with universal joints 23 and 24, in order to obtain a more suitable spacing of the control knobs on the front side of the machine base. For example, the illustrated embodiment, in FIG. 2, shows that the left-hand throttle members and their associated control knobs 22 are arranged substantially in coaxial alignment, while each right-hand throttle member, being closely spaced to the left-hand throttle member, requires universal joints 23' and 24', in order to permit adequate spacing of control knob 21 from control knob 22.

It should be understood that the control shafts with universal joints extending across the cooler compartment 47 could be replaced with flexible shafts or other rotation-transmitting means which permit an offset positioning of the control knobs in relation to the rotational axis of the throttle members.

In FIG. 3 is shown a typical arrangement of a set of control knobs on the front side of the machine. Knobs 21 and 22 of the top row, for example, control the opening and closing speeds of the die closing unit, the gauge 40 indicating the closing pressure. The second and third levels 37 are shown without knobs and gauges; they would be used for one or two injection units. Additional control knobs 33, 34, etc. are arranged further below. The openings 38 and 39 in the front longitudinal wall 1'" serve for the circulation of cooling air through the cooler compartment 47 and for access to the control shafts 25 and 25'.

A fluid filter 12 is arranged on the outside of the rear longitudinal wall 1.sup.IV (FIG. 2), in the space between the uppermost distributor 8, the solenoid 10, and the cantilever arm 18. The filter 12 is arranged vertically, just below the top level of the machine base. In its upper portion the filter has a magnetic particle separator, and in its lower portion it includes a cylindrical screen filter unit.

A pressure feed line (not shown) leads from the hydraulic pump 4 to the top end of the distributor block assembly, and a return line leads from the bottom end of the distributor block assembly to the filter 12 and from there, via a connector 44 and a line 13, to the cooler 14, and through a return outlet 15 into the hydraulic fluid reservoir 2. These connections to the distributor block assembly facilitate servicing of the distributor block components, because they eliminate the need for emptying the fluid reservoir 2, in order to prevent discharge of fluid through the open distributor block assembly 8, 9, 10, and 11.

It should be further understood that the foregoing disclosure describes only a preferred embodiment of the invention and that it is intended to cover all changes and modifications of this example of the invention which fall within the scope of the appended claims.