CN108071626B

CN108071626B - Molding machine and method for operating the same

Info

Publication number: CN108071626B
Application number: CN201710844551.XA
Authority: CN
Inventors: A·洛纳克尔; H·施泰因帕泽; H·蔡德尔霍费尔
Original assignee: Engel Machinery Shanghai Co Ltd
Current assignee: Engel Machinery Shanghai Co Ltd
Priority date: 2016-11-17
Filing date: 2017-09-19
Publication date: 2021-03-26
Anticipated expiration: 2037-09-19
Also published as: CN108071626A

Abstract

The invention relates to a molding machine, comprising a hydraulic drive unit, comprising: a pump (4) driven by the motor (3), the pump being a regulated pump; a regulating or control unit (5) for regulating and/or controlling the drive unit (1) to a set operating point of the drive unit, and a memory (6) connected to the regulating or control unit, wherein a relationship between a characteristic variable for the sound caused directly or indirectly by the drive unit and a data record representing different operating points of the drive unit is stored in the memory, the operating points of the data record containing at least one pump rotational speed and pump deflection, and the regulating or control unit is designed to select, for a desired delivery quantity, the set operating point on the basis of the relationship, the set operating point comprising the set pump rotational speed and the set pump deflection, the molding machine being an injection molding machine, a die casting machine or a press. The invention also relates to a method for operating a drive unit.

Description

Molding machine and method for operating the same

Technical Field

The invention relates to a hydraulic drive unit for a molding machine, to a molding machine comprising such a drive unit, and to a method for operating a hydraulic drive unit for a molding machine.

Background

For energy reasons, hydraulic drives are always driven more frequently by speed-regulated motors, in order not to have unnecessary idling losses during standstill, but also to operate the drive system with better efficiency in the partial load range. In this case, not only can the fixed displacement pump be driven and the required delivery quantity be adjusted solely by the motor speed, but the motor with varying speed is combined with the adjustable displacement pump and therefore has in fact two degrees of freedom (motor speed, pump deflection) when selecting the desired delivery quantity.

In the case of solutions with regulated pumps, the external delivery quantity is therefore formed by the product of the motor speed and the pump deflection (also referred to as pump deflection angle). However, any delivery volume that is below the maximum possible delivery volume of the system can be started at different operating points.

Example (c): the 50% outer delivery volume can be realized in the following operating state:

-50% pump deflection and 100% rotational speed,

100% pump deflection and 50% rotational speed and

all the gradations in between.

It is known from AT 11681U 1 or DE 102009018071 a1 to use this fact in optimizing the efficiency of a hydraulic drive. The noise emission of the hydraulic drive or of the molding machine together with the hydraulic drive is not taken into account here.

Disclosure of Invention

The object of the present invention is therefore to provide a hydraulic drive unit, a molding machine and a method for operating a hydraulic drive unit, in which a lower-noise operation is possible than in the prior art.

The object is achieved by a molding machine comprising a hydraulic drive unit, the drive unit comprising:

a pump driven by a motor, the pump being a regulated pump,

an adjustment or control unit for adjusting and/or controlling the drive unit to a theoretical operating point of the drive unit, and

-a memory connected to the regulating or control unit,

the method is characterized in that a relationship between a characteristic variable for the sound generated directly or indirectly by the drive unit and a data record representing different operating points of the drive unit is stored in a memory, the operating points of the data record containing at least one pump rotational speed and pump deflection, and the control unit is designed to select a target operating point for a desired delivery quantity on the basis of the relationship, the target operating point comprising the target pump rotational speed and the target pump deflection, and the molding machine is an injection molding machine, a die casting machine or a press machine.

-a pump driven by a motor,

-a memory connected to the regulating or control unit,

characterized in that a relationship between characteristic variables for sound caused directly or indirectly by the drive unit and data records representing different operating points of the drive unit is stored in a memory, the characteristic variables being one or a combination of the following:

-a sound pressure,

-the amount of pressure pulsations in the hydraulic line,

-input by an operator based on perception of sound intensity,

wherein the regulating or control unit is designed to select a theoretical operating point on the basis of the relationship and the molding machine is an injection molding machine, a die casting machine or a press.

The object is also achieved by a method for operating a hydraulic drive unit of a molding machine according to the invention, in which a pump is driven by means of a motor, characterized in that,

providing a relationship between a characteristic variable for the sound caused directly or indirectly by the drive unit and a data record representing different operating points of the drive unit, wherein the operating points of the data record contain at least one pump rotational speed and pump deflection; and is

For a desired delivery quantity, the drive unit operating point is selected as a setpoint operating point for adjusting and/or controlling the drive unit on the basis of the relationship, said setpoint operating point comprising a setpoint pump rotational speed and a setpoint pump deflection.

-providing a relation between a characteristic quantity for sound caused directly or indirectly by the drive unit and data records representing different operating points of the drive unit, the characteristic quantity being one or a combination of:

-a sound pressure,

-the amount of pressure pulsations in the hydraulic line,

-an operator input based on sound intensity perception;

and selecting the drive unit operating point as a theoretical operating point for adjusting and/or controlling the drive unit based on the relationship.

It is provided here that a relationship is provided between characteristic variables for the sound caused directly or indirectly by the drive unit and data records representing different operating points of the drive unit, and that the operating point of the drive unit is selected as a setpoint operating point for adjusting and/or controlling the drive unit on the basis of the relationship.

The applicant's research has shown that the generally assumed relationship of the pump motor being automatically quieter at low rotational speeds is not suitable. The present invention utilizes this unexpected knowledge to enable lower sound operation.

This optimization of the noise emission can be used instead of or in combination with the efficiency optimization as described at the outset.

The invention can be used in a molding machine. The molding machine is, for example, an injection molding machine, a die casting machine, a press machine, or the like.

Provision may be made for the motor to be regulated or controlled in accordance with the rotational speed.

The characteristic variable for the sound caused directly or indirectly by the drive unit may be a sound level, for example a sound pressure. This allows the operator to intuitively reproduce the relationship.

However, the characteristic variable may also be a quantity of vibrations of a component of the device, a quantity of pressure pulsations in the hydraulic line or an input of the operator based on a perception of sound intensity. Of course, combinations of these parameters may also be used.

The operating point of the data record may comprise at least one pump rotational speed and/or pump deflection.

It can be provided that the determined operating point of the data record is marked as undesired and the control unit is designed to not use the range of undesired operating points as a setpoint operating point or to change the setpoint operating point if the setpoint operating point is in the range of undesired operating points.

On the basis of the measurements and empirical values, the most unfavorable rotational speed can be determined in different operating states in accordance with the sound level and can be avoided in the future when the motor/pump unit is actuated. In other words, an undesired rotational speed range is determined on the basis of previous measurements, wherein, nevertheless, a desired external delivery volume is achieved in the desired rotational speed range by means of a changed pump deflection.

It may also be provided that the operating point is changed if the current operating point falls in an undesirable range.

In addition, the speed range is not limited to an undesired speed range. Undesirable ranges of pump deflection may also be used and combinations thereof may of course also be used. That is, completely specific values of the rotational speed and the pump deflection can be marked as undesired ranges.

It can also be provided that a specific operating point of the data record is marked as desired, and the control unit is designed to select a setpoint operating point from a range of desired operating points.

This allows not only to avoid operating points with particularly high noise emissions, but also operating points with particularly low-sound operation to be deliberately controlled. The range of desired operating points may be similar to the range of undesired operating points being the range of rotational speeds, the range of pump deflections and combinations thereof.

The provided relationships can be stored in advance (for example during the production of the hydraulic drive unit or the molding machine) or can be adapted at defined intervals or continuously, in particular during operation, for example on the basis of measured values of a measuring instrument for measuring the characteristic variable.

However, the measuring device for measuring the characteristic variable can also be used for regulation or control, the measured value of the measuring device being used as a feedback variable (ru ckf ru).

In this case, it may be advantageous to measure the characteristic variable not only at every arbitrary time, but also locally (for example close to the working space). A calibration process can then be started in which the motor speed (for example in a pressure regulation operation) is slowly increased (see also the figure). The undesired range may then be determined and/or re-determined, for example.

However, a permanent or continuous measurement of the characteristic variable may also offer advantages. The fixedly (or also movably) mounted and permanent measuring device on the system may not only determine possible interference fields in a standardized and defined state, but also evaluate the actual system cycle or the respective freely selectable sequence and send it to the optimization method.

An example for this is:

increased noise emissions occur during metering in injection molding machines. The measuring device evaluates the actual state only during the "metering" of the sequence and the device autonomously moves the sequence to different operating points (for example different motor speeds) in the next cycle and determines the technically best state of the noise, which is then used in the future.

The measuring instrument for measuring the characteristic variable may be configured differently. The increased noise emission can also be inferred from the evaluation of other sensors present.

For an example of a possible measurement instrument:

a) direct sound pressure level measurement (complex, but most effective),

b) vibration measurement on equipment items such as frames, flat coverings, grills, etc. (relatively low cost sensors, which can be targeted at potentially interfering resonators),

c) measurement of pressure pulsations in the pressure line (by selecting operating points with lower pressure pulsations also the device is less excited; the advantages are that: pressure sensors that can evaluate the hydraulic system as it exists) and

d) the perception of the operator or operator of the device (the operator may simply choose the operating mode for which it feels most comfortable).

The methods a), b), and d) can be used both in a fixedly defined position of the device and also in a completely location-variable manner. That is to say, it is possible to position the changing sensors in a completely targeted manner at selected locations in order to optimize the noise emission there precisely (for example acoustic measurements or subjective evaluations on the working space; vibration measurements on the glass plate of an adjacent office or the like).

Different methods (forbidden ranges, continuous measurements, etc.) and different measurement methods for performing the invention can be freely combined. This is illustrated in the following table.

It is also possible to choose between peak or average optimization in all methods.

Furthermore, it can be provided that the control or regulating unit takes into account the minimum delivery power, the minimum volume flow to be delivered (also referred to as external delivery volume) and/or the minimum pressure to be maintained when selecting the setpoint operating point.

Furthermore, it can be provided that the control or regulating unit takes into account the energy efficiency, in particular the efficiency of the hydraulic drive unit, when selecting the setpoint operating point. Similarly to the selection of the operating point on the basis of the characteristic variables for the sound generated by the drive unit, the measured values of the measuring device for measuring, for example, the power can also be used in an additional selection on the basis of the efficiency in terms of energy. Furthermore, the determination of the desired and/or undesired efficiency range can be carried out analogously with regard to the efficiency in terms of energy.

In a particularly preferred embodiment, the operator can select whether the operating point should be selected based on the characteristic variables or on the efficiency in terms of energy. If this is the first case, for example, the desired area is first determined. In this (characteristic-parameter-based) desired region, the operating point can then be determined accurately on the basis of the efficiency in terms of energy. The method can be similarly implemented if the operator sets the priority to the efficiency in terms of energy, wherein the desired efficiency range assumes the role of the desired range.

In particular, other "variants" result in longer, constant plant sequences (for example during the re-extrusion phase or metering in an injection molding machine), since here generally monotonous and thus completely disturbing noise emissions can be involved.

Instead of monotonous constant noise in constant frequency, it is possible to move to a "sound model" that is more comfortable for the ear and freely selectable by the operator. This may be a simple oscillation or wave, but also a (simple) melody.

Furthermore, it is possible to use speed or sound changes for longer, constant sequences in order to acoustically indicate the end of the sequence.

Functions as fault or alarm signals are also conceivable. If, for example, the automatic cycle is interrupted based on a fault report, a siren signal can be generated using the motor/pump combination.

The use of two degrees of freedom, such as motor speed and pump deflection, offers many possibilities for providing the same external delivery volume with different acoustic properties.

The invention can also be used in conjunction with a fixed displacement pump, although only one degree of freedom is then available (rotational speed) and a change in the operating state always leads to a change in the external delivery volume.

A molding machine comprising a hydraulic drive unit according to the invention is also claimed.

Drawings

Further advantages and details of the invention emerge from the figures and the description of the figures relating thereto. Shown here are:

fig. 1 shows the results of the applicant's study, in which the sound pressure level is measured in dependence on the pump speed;

FIG. 2 shows the diagram of FIG. 1, wherein additionally desired and undesired ranges are shown;

fig. 3 shows the diagram of fig. 2, wherein additionally the efficiency of the drive unit is shown;

fig. 4 shows a schematic view of a drive unit together with a supplied consumer of an injection molding machine;

FIG. 5 shows a flow chart of another embodiment of the method according to the invention and

fig. 6 shows a flow chart of an alternative method for additional optimization of efficiency.

Detailed Description

In fig. 1, both the measured sound pressure level S and the pump rotational speed n are recorded in each case with respect to time. The rotational speed is increased substantially linearly in order to establish a relationship between the sound pressure level s and the pump rotational speed n.

As can be seen from fig. 1, the hitherto assumed monotonous relationship between sound intensity (sound pressure S is used as the characteristic variable as mentioned) and pump rotational speed n does not apply. But rather clear minima and maxima appear through interference and resonance effects. In particular, it can be advantageous to increase the rotational speed slightly at certain operating points in order to achieve a reduction in the sound pressure.

Specifically, the motor/pump system was accelerated from 200 rpm up to 2600 rpm at 200 bar in pressure maintenance operation and the sound pressure level of the total system was measured. It is very clearly seen that the sound pressure level peaks at about 1700 rpm and about 1900 rpm (81 and 80dBA) are significantly smaller at a rotational speed of about 1800 rpm with only small changes (about 73 dBA). From this table, the optimized pump speed N can now be read. Alternatively, the desired region E is first determined. This is shown in fig. 2.

As an additional condition for the optimized pump speed n or the desired range E, a minimum pump speed can additionally be used (if, for example, an at least maintained external delivery quantity is only achieved by a specific minimum speed). In the present example, a minimum rotational speed of 1600 revolutions per minute is assumed. As can be easily derived from the diagram, the actuation of the very low rotational speed is not optimal, since this leads to a louder operation than the operating point in the desired region E. The corresponding region with a high sound pressure is marked as the undesired range U.

Additionally, an optimization of the efficiency W can also be carried out. This is illustrated in fig. 3, in which the efficiency W is additionally recorded.

Two points P1 and P2 are likewise recorded, which are each in a separate desired region E. However, since point P2 provides a higher efficiency P than point P1, the P2 functions well as the operating point.

The data of fig. 3 may be stored in the memory 6 of the control or regulating unit 5. It can also be provided that the relationship is modified by the measured values of the measuring device 7 for detecting, for example, the sound pressure (for example, if the corresponding measured value differs from the sound pressure curve S of fig. 3 by another sound pressure which is present at the respective pump rotational speed n).

Fig. 4 shows a drive unit 1 according to the invention together with a schematically shown molding machine 2. Only the components of the molding machine 2 that are important for the invention are shown. These are a closing cylinder 8 for closing the closing unit, a pressure cylinder 9 for pressure and injection nozzles, an injection cylinder 10 for injecting the quantity of plastic, and a hydraulic motor 11 for metering the quantity of plastic.

The drive unit 1 has a motor 3 and a pump 4 driven by the motor 3, which in this case is embodied as a pump 4 with a variable pump deflection α. Hydraulic fluid, preferably oil, pressurized by a tank 12 is supplied to the consumers by a pump 4.

The drive unit 1 likewise has a control or regulating unit 5, which controls or regulates both the motor 3 and the pump deflection α of the pump 4.

In addition to the relationship between the sound pressure S and the pump speed n, it is of course also possible to store the relationship between the sound pressure S and not only the pump speed n but also the pump deflection α in the memory 6.

In this exemplary embodiment, a measuring device 7 for measuring the sound pressure S is also present.

Fig. 5 shows a flow chart for an alternative method according to the invention, which can be carried out during the operation of the molding machine 2. The method steps of metering are respectively used for the pump speed n in different molding cycles₁To n_nAnd pump deflection to alpha_nDifferent values of (2) are implemented. The sound level S is also measured during each molding cycle. The control or regulating unit 5 can then extract an optimum value from the measurement and can subsequently meter it with the optimum pump speed n and pump deflection α.

Fig. 6 is a flow chart of an optional additional method, wherein the efficiency of the drive unit 1 is also subject to optimization.

Here as described previously in fig. 5, however, no individual optimized value pair is output, but rather a certain number of acceptable value pairs.

In addition, the power received by the motor 3 and the delivery power of the pump 4 are measured in each molding cycle. The value pair optimized for the pump rotational speed N and the pump deflection α not only in terms of the sound level S but also in terms of the efficiency W can then be selected from the value pair identified as acceptable.

Alternatively, the efficiency according to fig. 6 may be optimized first and the sound level according to fig. 5 may be optimized by the value pairs selected here.

Claims

1. A molding machine including a hydraulic drive unit, the drive unit including:

-a pump (4) driven by a motor (3), said pump being a regulated pump;

-a measuring instrument (7) for measuring a characteristic quantity for sound caused directly or indirectly by the drive unit (1);

-an adjustment or control unit (5) for adjusting and/or controlling the drive unit (1) to a theoretical operating point of the drive unit (1); and

-a memory (6) connected to the regulating or control unit (5);

characterized in that a memory (6) stores a relationship between the characteristic variable, which is a sound pressure, and a data record representing different operating points of the drive unit (1), the operating points of the data record containing at least one pump rotational speed and pump deflection, the measuring device being designed to measure the characteristic variable close to the working space in a freely selectable sequence of a plant cycle of a molding machine, which includes a theoretical pump rotational speed and a theoretical pump deflection, in order to provide and/or adapt the relationship, and the regulating or control unit (5) being designed to select a theoretical operating point for a desired delivery quantity on the basis of the relationship, the theoretical operating point including the theoretical pump rotational speed and the theoretical pump deflection, the molding machine being an injection molding machine, a die casting machine or a press.

2. Moulding machine according to claim 1, characterized in that the regulation or control of the motor (3) is set according to the rotational speed.

3. Moulding machine as claimed in claim 1 or 2, characterized in that a determined operating point of the data record is marked as undesired and the regulating or control unit (5) is configured to not use the range of undesired operating points as a theoretical operating point or to change the theoretical operating point if the theoretical operating point is in the range of undesired operating points.

4. Moulding machine as claimed in claim 1 or 2, characterized in that the determined operating point of the data record is marked as desired and the regulating or control unit (5) is designed to select a theoretical operating point from a range of desired operating points (E).

5. Moulding machine according to claim 1 or 2, characterized in that the control or regulating unit (5) is configured to adapt the relation stored in the memory (6) during operation on the basis of the measured values of the measuring instrument (7).

6. Moulding machine as claimed in claim 1 or 2, characterized in that the regulation of the motor (3) is set, wherein the regulating or control unit (5) is designed to use the characteristic variable as a feedback variable.

7. Moulding machine according to claim 1 or 2, characterized in that the regulating or control unit (5) is designed to take into account the minimum delivered power, the minimum volume flow to be delivered and/or the minimum pressure to be maintained when selecting the theoretical operating point.

8. Moulding machine according to claim 1 or 2, characterized in that the regulating or control unit (5) is configured to take into account the efficiency in terms of energy when selecting the theoretical operating point.

9. Moulding machine according to claim 1 or 2, characterized in that the regulating or control unit (5) is configured to take into account the efficiency of the hydraulic drive unit (1) when selecting the theoretical operating point.

10. Method for operating a hydraulic drive unit of a molding machine according to one of claims 1 to 9, wherein the pump (4) is driven by means of the motor (3) and a characteristic variable for the sound caused directly or indirectly by the drive unit (1) is measured by means of a measuring instrument (7), characterized in that,

-providing a relationship between the characteristic variable and a data record representing different operating points of the drive unit (1), wherein the characteristic variable is a sound pressure, the operating points of the data record containing at least one pump rotational speed and pump deflection, wherein, for providing and/or adapting the relationship, the characteristic variable is measured close to the working space in a freely selectable sequence of a machine cycle of the molding machine; and is

-selecting, for a desired delivery quantity, an operating point of the drive unit (1) as a theoretical operating point for adjusting and/or controlling the drive unit (1) based on the relationship, the theoretical operating point comprising a theoretical pump rotational speed and a theoretical pump deflection.