DE2263797A1 - INJECTION MOLDING MACHINE - Google Patents

Description

DR. MÜLLER-BORE DIPL-PhYS. DR. MAN ITZ DIP ·.-CHEM. DR. DEUFEL DIPL.-lNG. FINSTERWALD DlPL.-lNG. GRÄMKOW

PATENT LAWYERS

28 DEC. 1572 D / Sh - B 1136

BEIiDISH JJfDUSiDRIAL EIASTIOS LIMIiDED Manchester, UK

Fuel casting machine

Priority: Great Britain v. December 28, 1971 No. 60222/71

The invention relates to hydraulically operated machines for injection molding of synthetic resin materials such machines are usually driven by electric motors, the hydraulic power being through throttle valves, along with hydraulic amplifiers, and sometimes through Gearbox between the hydraulic motors and the injection screws is controlled. Such arrangements are necessary to deliver the force changes that are necessary due to the injection molding cycles.

Inevitably, more hydraulic energy is generated than is required by the machine for the injection molding cycle, and the excess energy must be destroyed, usually being given off as heat.

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Dr. Müller-Bor * Dr. Manilz Dr. Deufel Dipl.-Ing. Finsterwald Dipl.-Ing. Grämkow Braunschweig, Am Bürgerpark 8 8 Munich 22, Robert-Koch-Strasse 1 7 Stuttgart-Bad Cannstatt, Marktstrasse Telephone (0531) 73887 Telephone (0811) 293645, Telex 5-22050 mbpat Telephone (0711) 567261 Bank: Central Cash Office · Bayer. Voiksbanken, Munich, account no. 9622 Post check: Munich 95495

Before a computer control or some other kind of process control can be applied to an injection molding machine, it is necessary that the hydraulics on the machine be changed becomes that it can incorporate some form of control which allows subtle changes in flow and pressure. Heretofore it has been assumed that there are only two "ways" by which this subtle change can be achieved can, namely the use of servo valves or by variable supply or servo pumps. Servo valves are very wasteful of energy to be destroyed, as mentioned above, and requires very clean oil for effective operation and servo pumps, which are more effective, are more expensive and also require clean oil " There are therefore expensive oil filter systems for the satisfactory one Operation of these known systems required.

The aim of the invention is to eliminate or reduce the above-mentioned disadvantages of using process control Injection molding machines.

According to the invention is in an injection molding machine for molding synthetic resin material by hydraulic Power is operated, the power is supplied at least by a hydraulic pump, which is varied by an electric motor

is driven
such speed / which is arranged and adapted to operate at speeds and torques which are each varied directly according to the hydraulic requirements of the machine during an injection molding cycle.

According to a preferred arrangement, the electric motor drives two tandem-coupled hydraulic pumps.

On large machines, a plurality of pumps can be used to achieve high injection speeds. The spray

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speeds are practically infinitely variable; they can be adapted to the tool for optimal molding results instead of changing the various valve settings as is the case with conventional injection molding machines necessary is.

The hydraulic circuit of an injection molding machine according to the invention is considerably simplified and can be simplified for operation on gauge control valves, being pressure relief valves not necessary for process control and are only installed for safety reasons.

Variable speed DC motors can operate for shorter periods of time during the injection molding cycle work at least twice their continuous output. A great saving in energy is achieved because the machine does the provides the exact power requirement of the cycle. Maximum force is only required for short periods of time during each injection molding cycle.

The injection molding machine according to the invention allows precise control of the pressure change and the amount of supplied oil. The control of the hydraulic flow and pressure are separate, which provides an improved injection molding technique because it allows high-speed spraying without exceeding the pressure required to push the mold or mold out. Causes press burrs. Infinitely fine control of the screw pressure or the pressure flow is possible without additional hydraulic controls.

In addition, the machine can be operated very slowly, which allows easier fault detection as a maintenance aid, and this feature is of general utility in the analysis of shape cycles.

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The machine delivers maximum force and torque at the injection stage of the molding cycle while the motor is during the cooling stage of the cycle is only working weakly to maintain a given torque, which is the required Provides maintenance pressure with practically no need for force

Since the pump or pumps are only running at full speed for part of the molding cycle, the noise is correspondingly reduced during machine operation »This also increases the service life of the pumps, and also remains the hydraulic fluid cools.

In a preferred embodiment of the invention, hydraulic Power of an injection molding machine model 155/50 (manufacturer BIPEL) through two impeller pumps or »capsule pumps one with a capacity of 77 liters (17 gallons) per minute and the other 86 liters (19 gallons) per minute and which are jointly driven by a 25 HP reversing motor that is fed with direct current The amount of direct current is controlled by an electronic drive with changing speed, which in turn controlled by its response to signals obtained from three sources:

1. A tachometer generator coupled to the drive shaft of the engine;

2ο a number of speed or speed text-related Adjusting devices. These are chosen by changing Resistance or impedance values set by digital switches j

3. Signals from the machine's electronic sequence control system.

This preferred embodiment is referred to below described in more detail on the attached drawing «

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The drawing is a schematic representation of part of the control circuit, with electrical lines through the letter "E" and hydraulic lines are denoted by the letter "H". The letter "T" denotes a hydraulröhes Reservoir for the injection molding machine.

The variable speed DC motor 1 becomes

Equals Oromwanar

fed from an alternating current source 3 via an alternating current / 2, whose output is controlled by the control unit 4 wM.

The tachometer generator 5 informs the control unit 4 whether the predetermined speed (from the speed-related digital switches, which are designated by X) has been reached and controls it at this speed. The torque related adjusters (labeled with the letter Y) receive information from pressure transmitters such as 11 to ensure that the current pressure is maintained Pumps 6 and 6 'is delivered, which a hydraulic main line H via the line H2, the valve 7 and the line H3 via the line H6, the valve 7' or «line H? Food. The pump 6 ¹ is normally only control for quickly syringes in operation and otherwise rests or is idle "The valves 8 and 9, the forward and return movement of the injection die, which is shown by 10. The valves 7 »7 ¹ » 8 and 9 are preferably each operated electrically, namely via a pneumatic pilot, but can also be operated by direct hydraulics. The limit switch 12 is actuated by the ram movement to inform the controller 4 of the completion of a stage in the cycle and to begin the next stage in the cycle. Accordingly, other signals from the machine's electronic sequence control system inform the controller what speed and speed what torque in the cycle

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are reached at any time. In other words, the machine is programmed and information is taken from the machine used to control the speed and torque of the motor during the cycle of operation. Operational the motor is controlled to accurately supply the hydraulic requirements of the machine during the injection molding cycle, and the method of control via electronic circuits results in a system that is suitable for the easy inclusion of the Repatriation and offering computer control systems «

Using the variable speed system described above, it is possible to quickly scan both flow and speed. Pressure can be changed by simply changing digital switches that are calibrated, for example in 0.1 % increments, like this

ο that if, for example, the normal maximum pressure 12 _r 4 MN / m

(1800 psi), it can be adjusted in steps of 12.4 KN / m ² (1.8 psi). For example, there can be 5 digital switches for setting the speed at which the oil flows and another 5 for the pressure, so that a setting of the maximum pressure is also selected for each given setting of flow or flow.

Thus, according to one method of operating the injection molding machine a value is set on a digital scale for the spray flow rate, and this value gives when taken into account the required spray speed (which may require the use of both pumps) »up a corresponding scale for the pressure is required considered maximum pressure set »This must be sufficient to allow the movement of the material to be formed through the Nozzle and locks to start the machine «When the punch is moved forward, the set speed will be maintain the oil flow until the ram has moved to the point where most of the material has become

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splashes and only a little oil is required. The pressure in the circle now rises to the maximum set as required Extent, and the engine speed drops by the Reduce oil flow to the level required to pack the mold.

Another feature of the invention is the ability of the machine to to operate at very low velocities by setting low flow velocities «. This is advantageous when molds are installed or run in and Form cycles are analyzed.

Furthermore, there are the following advantages by using the invention possible.

1. The cost is reduced because less force is required is;

2ο therefore less energy is converted into heat, and it is less cooling and cooling equipment required;

3ο flows and pressures can be set in small steps and be adjusted;

4-, settings can be repeated exactly;

5 «the noise is reduced and only comes mainly metal-to-metal contact when the machine opens or closes; and

6. if information from the converters regarding temperature and Viscosity of the MeltG is obtained, it can be used to determine the injection speed applied to the material to be molded Material pressure applied before and after mold packing and screw reflux rate to control to control the state of the melt.

Claims: 309828/0839

Claims (4)

Claims 1. Injection molding machine for the molding of synthetic resin , y materials, which is operated by hydraulic power and comprises hydraulic pumping means for the power supply, characterized in that it comprises a variable speed electric motor for driving the hydraulic pumping means, this motor being arranged and is arranged to operate at speeds and torques which each vary directly in accordance with the hydraulic requirements of the machine during an injection molding cycle. 2. Injection molding machine according to claim 1, characterized in that the hydraulic pump devices comprise two tandem-coupled hydraulic pumps. 3. Injection molding machine according to claim 2, characterized in that the hydraulic pumps are different Have capacityο 4. Injection molding machine according to one of the preceding claims, characterized in that an electronically controlled variable speed drive is provided with the motor to control the speeds and the speed torque is coupled. 5β injection molding machine according to claim 4, characterized in that the variable speed drive can be controlled by its response to signals received from (i) a tachometer generator that is connected to 309828/0839 the drive shaft of the engine is coupled, (ii) a plurality of torque and speed related Adjusting devices, the value of the signal being chosen by each by changing the resistance or impedance values which are adjustable by a digital switch and (iii) an electronic sequence control system the machine. p Injection molding machine according to claim 5 »characterized in that the torque-related adjusting devices are set up to receive and maintain information from pressure transmitters to ensure a preselected pressure, 7 · Injection molding machine according to one of the preceding claims, characterized in that the motor armature current is continuous to control the motor torque is measurable 309828/0839 Blank page