CN111516229B - Drive device for a molding machine and molding machine having a drive device - Google Patents

Abstract

The invention relates to a drive device for a molding machine, comprising: at least one hydraulically driven pressure pad through which a beam column or a movable mold platen of a molding machine is movable to apply a closing force; a conveying device for conveying hydraulic fluid, wherein the conveying device has a conveying cylinder, a conveying chamber formed in the conveying cylinder and filled with hydraulic fluid, and a conveying piston movable in the conveying chamber, which divides the conveying chamber into a first chamber and a second chamber; and a hydraulic line system filled with hydraulic fluid, via which the delivery device is connected to the pressure cushion, characterized in that the delivery device is designed as a two-stage force converter, wherein the second chamber is designed in two parts. The invention also relates to a forming machine with the driving device.

Description

Drive device for a molding machine and molding machine having a drive device

Technical Field

The invention relates to a drive device for a molding machine, in particular for an injection molding machine, comprising: at least one hydraulically driven pressure pad through which a beam column or a movable mold platen of the molding machine is movable to apply a closing force; a conveying device for conveying a hydraulic fluid, wherein the conveying device has a conveying cylinder, a conveying chamber formed in the conveying cylinder and filled with the hydraulic fluid, and a conveying piston movable in the conveying chamber, which divides the conveying chamber into a first chamber and a second chamber; and a hydraulic line system filled with hydraulic fluid, via which the delivery device is connected with the pressure pad. The invention further relates to a molding machine having such a drive.

Background

Various different drive means have been implemented on the closing side of the molding machine in order to perform the closing and opening movement of the movable mold platen. The closing movement is divided into two sections, namely a rapid stroke, in which the mold platen passes through a relatively large section with a relatively low force, and a closing force; the mold platen hardly passes through the path during the closing force build-up and is pressed against each other by a relatively high force.

In particular for carrying out the closing force build-up, it has been known for many years to use hydraulically operated pressure pads. The quick stroke can also be performed via the pressure pad, or a quick stroke device separate from the pressure pad can be provided.

An example of a pressure pad for building up a closing force in a vertical closing unit of a molding machine is known from DE 102016006108 a 1.

EP 1388404B shows a hydraulic unit for an injection molding machine having an actuator which is operatively connected to a functional unit via an adjusting mechanism and a hydraulic force transducer. In this case, the adjusting movement of the input cylinder can be converted into a corresponding movement of the output cylinder. In order to compensate for leakage between the pressure chambers, reference means are provided, by means of which a correct setting of the pressure can be carried out. The reversing valve is arranged for connecting the inflow and outflow lines.

EP 1331079B 1 shows a two-plate closing system of an injection molding machine, in which a dual-acting closing pressure piston mounted in a closing pressure cylinder is assigned to a stationary mold platen. The rapid-motion closing of the closing unit is triggered by a spindle which is driven by a drive motor via a toothed belt, wherein the various valves are switched accordingly for this purpose. To build up a closing force, pressure fluid is conducted via the open valve into the closing chamber of the closing cylinder by further rotation of the spindle in the closing direction from the pressure chamber. After closing the valve, the desired closing pressure is cut off for the duration of the injection process, and the hydraulic fluid under pressure acts in the closing pressure chamber on the annular piston faces of the four closing pressure pistons. In this arrangement, it is disadvantageous that the main shaft is directly lubricated by the hydraulic oil, since the hydraulic oil has a viscosity which is unfavorable for the lubrication. The wear of the spindle is therefore very high and the service life is very short, so that such spindles must be replaced frequently, which again is costly. Furthermore, it is disadvantageous that during a rapid stroke, the hydraulic oil must be fed back on the closing force side of the chamber closing the pressure piston, thereby increasing the required volume considerably. But then the volume must be compressed again via the spindle, whereby a considerable compression stroke is required, which in turn inevitably leads to a large structural length. Furthermore, the device requires a fuel tank, which in turn requires a large installation space. The amount of hydraulic oil required in the system is also greatly increased by the long lines and tanks.

EP 2242633B 1 shows a linear drive for generating an adjusting movement and applying a large holding force. A disadvantage similar to the document described in detail above is that, on the one hand, an oil tank is also required here, and, on the other hand, the main shaft is lubricated directly in the disadvantageous hydraulic oil. Furthermore, it is disadvantageous that all forces have to be absorbed directly by the spindle. This document also shows a sub-optimal combination of drive power and required structural space.

Disclosure of Invention

It is therefore an object of the present invention to provide a drive device which is improved in comparison with the prior art. In particular, the disadvantages specified should be eliminated.

It is therefore proposed according to the invention that the conveying device is designed as a two-stage force converter, wherein the second chamber is designed in two parts.

In principle, it is possible to design the cross section (viewed perpendicular to the longitudinal (movement) axis) of the conveying chamber to be non-circular. Thus, the cross-section may be quadrangular, for example. It is also possible for the two parts of the two-part chamber to lie alongside one another in cross section. Preferably, however, it is provided that the second chamber has an axially outer sub-chamber which is annular in cross-section and an axially inner sub-chamber which is separate from the axially outer sub-chamber. In principle, however, it is also possible for the first partial chamber and the second partial chamber to be arranged upside down. Preferably, it is provided that the two partial chambers are connected to one another, viewed along the longitudinal axis.

It is preferably provided that the drive device has a shut-off device for interrupting the connection of the pressure pad to the conveying device and a connecting line connecting the first chamber with the second chamber for conveying hydraulic fluid between the chambers when the connection of the pressure pad to the conveying device is interrupted by the shut-off device. It is thereby possible to change the initial position of the pressure pad by means of the conveying device. That is, the mold height is adjusted, and the driving device is designed based on the mold height. The transport device is used not only for applying the closing force but also for positioning the beam column. The conveying device forms a mould height adjusting device together with the pressure pad. Thus, the change of the position of the beam column at the time of tool change can be performed in a simple manner. Furthermore, the solution is very compact.

For simple operation, the pressure pad is designed as a piston-cylinder unit. According to a preferred embodiment, it is provided that the pressure pad has a pad cylinder, a pressure pad chamber which is formed in the pad cylinder and is filled with hydraulic fluid, and a pad piston which is movable in the pressure pad chamber, wherein the pad piston divides the pressure pad chamber into a closing pressure chamber and an opening pressure chamber.

Hydraulic fluid is the fluid required in fluid technology to transfer energy (volume flow, pressure) into a hydraulic system. The term "hydraulic fluid" includes hydraulic liquids or corresponding mixtures of liquids and gases. Preferably, hydraulic oil is used as the hydraulic fluid.

In general, the delivery device is embodied as a piston pump.

The first and/or the second chamber of the delivery chamber can be designed as a pressure chamber. That is, the chamber is loaded with (hydraulic) pressure.

The lines of the hydraulic line system can be of any desired design, as long as the conveying device and the pressure cushion can be sufficiently pressurized. The lines of the hydraulic line system also include the terms hoses, holes, pipes, etc.

Preferably, the hydraulic line system has a first hydraulic line which connects the closed pressure chamber of the pressure mat to the first chamber of the conveying device. It can furthermore be provided that the hydraulic line system has a second hydraulic line which connects the opening pressure chamber of the pressure cushion with a second chamber of the delivery device. Furthermore, it can be provided that the hydraulic line system has a coupling line which connects the first hydraulic line and the second hydraulic line.

It can furthermore preferably be provided that a first switching element is provided in the first hydraulic line between the branch to the coupling line and the closing pressure chamber, preferably for carrying out a conveying means idle stroke, and/or a second switching element is provided in the second hydraulic line between the branch to the coupling line and the opening pressure chamber, preferably for carrying out a conveying means idle stroke.

It is particularly preferably provided that the connecting line consists of a section of the first hydraulic line which extends from the first pressure chamber to a branch leading to the coupling line, the coupling line and a section of the second hydraulic line which extends from the branch of the coupling line to the second pressure chamber.

In order to be able to achieve the shut-off, it is preferably provided that the first and second switching elements can be brought into the closed position, preferably in order to carry out an idle stroke of a delivery piston of the delivery device. Thus, the first switching element and the second switching element together form a shut-off device.

Each switching element is preferably designed as a fluidic switching element. In particular, as the switching element, a switchable valve or cartridge valve can be used.

In order to carry out the pressure cushion stroke, it can preferably be provided that a third switching element is provided in the coupling line. Preferably, it is provided that, for carrying out a die height adjustment stroke of the pad piston of the pressure pad, the first and second switching elements can be brought into the open position and the third switching element can be brought into the closed position.

In order to be able to dispense with the oil tank, it is preferably provided that the pressure cushion chamber, the feed chamber and the hydraulic line system form a closed hydraulic circuit.

It is furthermore preferably provided that, preferably in the region of the coupling line, the hydraulic line system is connected to a storage device, which is preferably a bladder storage. Such a hydraulic accumulator is used to compensate for the (minimum) differential volume due to the compression of the hydraulic liquid.

In particular, when a storage device is provided, it is expedient if the storage device is connected to the coupling line via a branch line branching off from the coupling line, wherein a third switching element is provided in the coupling line between the branch line and the first hydraulic line, preferably for carrying out a mold height adjustment stroke that can be brought into the closed position, and a fourth switching element is provided in the coupling line between the branch line and the second hydraulic line, preferably for carrying out a mold height adjustment stroke that can be brought into the closed position.

In particular, in the case of a conveying device designed as a two-stage force converter, it is expedient if the first hydraulic line has a first branch line and a second branch line, wherein the first branch line is connected to the annular, axially outer partial chamber and the second branch line is connected to the axially inner partial chamber. Preferably, it can also be provided that the fifth switching element is arranged in the second branch and the sixth switching element is arranged in the first branch.

According to a preferred embodiment, it is provided that the conveying device can be driven by an electric drive. It is proposed in particular that the delivery piston can be moved, preferably linearly, relative to the delivery cylinder by means of an electric drive.

A molding machine, in particular an injection molding machine, having a drive according to the invention is also claimed. Preferably, the molding machine has an injection unit and a closing unit, wherein the closing unit has a machine base, a stationary mold platen connected to the machine base and a mold platen movably mounted on the machine base, the movable mold platen being drivable by a drive.

There are two common designs of molding machines, namely as a two-plate or three-plate machine with a beam column or as a machine without a beam column.

In a first variant, it is proposed that the closing unit has four beams which extend through the mold platen, wherein each beam is connected to a respective pad piston of a pressure pad of the drive.

In a second variant, it is proposed that the closing unit be designed without a beam column, wherein the cushion piston is connected to the movable mold platen and the cushion cylinder is connected to or formed in an end plate of the closing unit that is fixed to the machine base.

Drawings

Further details and advantages of the invention are explained in more detail below with reference to the exemplary embodiments shown in the figures by means of the drawing description. In the drawings:

fig. 1 shows a forming machine in the form of a beam-column machine with a drive device in a schematic side view;

figure 2 shows in a schematic side view a forming machine in the form of a beamless column machine with a drive;

fig. 3 schematically shows details of the drive device together with the delivery device, the hydraulic line system and the pressure pad;

fig. 4 shows the switching position of the drive in the first idle stroke of the profile part stroke;

fig. 5 shows the switching position of the drive in a first adjustment stroke of the profile part;

fig. 6 shows the switching position of the drive in the second idle stroke of the profile part stroke;

fig. 7 shows the switching position of the drive in a second adjustment stroke of the profile part;

fig. 8 shows the new initial position after the end of the profile stroke;

fig. 9 shows the switching position of the drive device when compensating for position tolerances;

FIG. 10 shows the switching position of the drive means when building up the closing force;

fig. 11 shows the switching position of the drive means while maintaining the closing force;

fig. 12 shows the switching position of the drive means at the sealing for reducing the closing force;

fig. 13 shows the switching position of the drive when the closing force is reduced;

fig. 14 shows the switching position of the drive device when the beam column or the transmission rod is reset;

fig. 15 shows an initial position of the drive device;

fig. 16 shows the switching position of the drive device when an increased opening force is applied;

fig. 17 shows a schematic view of a drive device and a conveying device in the form of a single-stage pressure transducer;

fig. 18 shows a drive device with a delivery device in the form of a single-stage pressure transducer arranged in a pad piston; and

fig. 19 shows the drive device with a delivery device in the form of a two-stage pressure transducer arranged in the pad piston.

Detailed Description

Fig. 1 shows a schematic side view of a molding machine 2 with an exemplary drive 1. In this case, the forming machine 2 is constructed as a two-plate machine with a beam column 4. The molding machine 2 has a closing unit 12 and an injection unit 11 as main components.

The injection unit 11 is only schematically shown. By means of the injection unit 11, liquid material, for example plastic or metal melt, can be introduced into a cavity formed in the forming mould 16. In this chamber, the liquid material is first solidified into a shaped part, which is then removed, in particular pushed out, of the shaping tool 16.

The closing unit 12 has a machine base 13 (also referred to as a frame), a stationary mold platen 14 which is fixedly connected to the machine base 13, and a mold platen 5 which is movably supported on the machine base 13. Furthermore, the closing unit 12 has a beam column 4 which runs through the two mold platens 5 and 14. In the region of the movable mold platen 5, a locking device 17 is provided, which axially surrounds the beam column 4 at least in sections. The locking device 17 holds the tool platen 5 to the beam column 4 in a fixed or form-fitting or force-fitting manner when the forming tool 16 is closed. In the locking position of the locking device 17, the application of a closing force can be achieved. The locking device 17 can have a half-shell 17a and a half-shell 17b (also referred to as locking nuts), respectively, which can be connected, preferably clamped, in a form-fitting or force-fitting manner to the beam column 4. Mounted on the two mold platens 5 and 14 are mold halves 16a and 16b, respectively. The two mold halves 16a and 16b together form the forming mold 16. In the closed state, at least one cavity (not shown) is formed in the forming die 16.

The closing unit 12 has a drive 1, by means of which the mold platens 5 and 14 and thus the mold halves 16a and 16b can be moved relative to one another. The drive 1 can be designed such that it has its own quick stroke device for performing a quick stroke (a relatively long path with relatively low forces). The quick-action stroke device can be embodied, for example, in the form of a spindle drive or in the form of a crank system. Such a quick stroke device can be provided in the area of the (left side) of the movable mold platen 5 and move the movable mold platen relative to the fixed mold platen 14. The quick stroke device is not shown in fig. 1.

The drive device 1 also has a plurality of pressure pads 3 for applying a closing force. One pressure pad is described in exemplary detail below. The pressure pad 3 has a pad cylinder 30, which is connected to the stationary mold platen 14. The pressure pad 3 can, for example, be arranged on the stationary mold platen 14 or integrated into it. A pressure pad chamber 31 is formed in the pad cylinder 30, and is filled with a hydraulic fluid (e.g., hydraulic oil). A pad piston 32 is linearly movably supported in the pressure pad chamber 31. The pad piston 32 divides the pressure pad chamber 31 into a closed pressure chamber 33 and an open pressure chamber 34. The pad piston 32 is connected to the beam column 4. The pressure pad 3 is connected to the conveying device 6 via a hydraulic line system 7. The pressure pad 3 forms the drive 1 together with the hydraulic line system 7 and the conveying device 6. If no separate quick stroke device is provided, both the quick stroke and the closing force application are performed by means of the drive device 1. The conveying device 6 serves for the supply and discharge of hydraulic fluid to and from the pressure pad 3. The conveying device 6 has a conveying cylinder 61, a conveying chamber 62 formed in the conveying cylinder 61, and a conveying piston 63 movable in the conveying chamber 62. The transfer piston 63 divides the transfer chamber 62 into a first chamber 64 and a second chamber 65. Since the conveying device 6 is in this case designed as a two-stage force transducer, the first chamber 64 has an axially outer partial chamber 66 and a (smaller) axially inner partial chamber 67. The delivery piston 63 is connected to a delivery rod 68 which divides the first chamber 64 into two sub-chambers 66 and 67. The delivery piston 63 is connected to an electric drive 10 (shown schematically) via a drive rod 69. Via the electric drive 10, the delivery piston is movable in translation in a delivery cylinder 61. The electric drive 10 can be configured, for example, as a rotary hollow-shaft motor which drives a drive rod 69, which is partially configured as a spindle, linearly via a spindle nut. The position of the transport device 6 can be freely selected. As shown, the conveying device 6 can be arranged at any point separate from the pressure mat 3. However, the conveying device 6 can also be integrated into the stationary mold platen 14 or into the pressure pad 3.

In fig. 2, the molding machine 2 is designed as a beam-column-free machine, of which only the closing unit 12 is illustrated. In such a beamless column machine, only one relatively large pressure pad 3 is provided. In this case, the pressure pad 3 is integrated into the end plate 15. The end plate 15 is fixed to the machine base 13. The cushion cylinder 30 is formed by the end plate 15 or is fixed to the end plate 15 (as already described). A pressure cushion chamber 31, in which a cushion piston 32 is movable again, is formed in the cushion cylinder 30. The pad piston 32 is connected to the movable mold platen 5 via a transmission rod 18. Via the transmission bars 18 (or via separate drives), the movable mold platen 5 can be moved along the machine longitudinal axis M relative to the stationary mold platen 14. In this embodiment too, the locking means 17 are again provided. The pad piston 32 divides the pressure pad chamber 31 into a closed pressure chamber 33 and an open pressure chamber 34. The pressure pad 3 is connected to the conveying device 6 via a hydraulic line system 7. The hydraulic line system 7 and its function will also be described in detail later.

Fig. 3 to 8 schematically show the drive 1 during the execution of the profile stroke. In this case, the drive (consisting of the pressure pad 3, the hydraulic line system 7, the conveying device 6 and the electric drive 10) serves as a mold height adjusting device.

In principle, the conveying device 6, the hydraulic line system 7 and the pressure cushion 3 are shown in fig. 3 to 8, such that they are formed in the stationary die platen 14 (or in the end plate 15). Of course, other configurations and arrangements can also be provided.

With reference to fig. 3, all components of the hydraulic line system 7 are explained in particular in detail. In general, a hydraulic line system 7 connects the conveying device 6 with the pressure pad 3.

The hydraulic line system 7 has a second hydraulic line 72 which connects the opening pressure chamber 34 of the pressure pad 3 with the second chamber 65 of the conveying device 6. The second hydraulic line 72 has a branch 75 leading to the coupling line 73, wherein the branch 75 divides the second hydraulic line 72 into a delivery section 72.6 and a pressure pad section 72.3. A second switching element (switchable valve) 82 is arranged in the pressure pad section 72.3 of the second hydraulic line 72. The switching element 82 is able to occupy an open position OS and a closed position SS.

The hydraulic line system 7 has a first hydraulic line 71 which connects the closed pressure chamber 33 of the pressure mat 3 with the first chamber 64 of the delivery device 6. First chamber 64 is comprised of an axially outer subchamber 66 and an axially inner subchamber 67. First hydraulic line 71 has a branch 76 leading to coupling line 73, wherein branch 76 divides first hydraulic line 71 into delivery section 71.6 and pressure pad section 71.3. A first switching element 81 is arranged in the pressure pad section 71.3. The first hydraulic line 71 (in particular its delivery section 71.6) comprises a first branch line 71a which is connected to the axially outer subcavity 66 and a second branch line 71b which is connected to the axially inner subcavity 67. The first branch 71a is divided into two sections by a branch 77. A sixth switching element 85 is provided in the first branch line 71 a. A fifth switching element 86 is arranged in the second branch 71 b.

The hydraulic line system 7 has a coupling line 73, which connects the first hydraulic line 71 and the second hydraulic line 72. The coupling line 73 forms together with (the delivery section 71.6 of) the first hydraulic line 71 and (the delivery section 72.6 of) the second hydraulic line 70 a connecting line. In the region of the coupling line 73, the hydraulic line system 7 has a storage device 9. The storage device 9 is connected to a coupling line 73 via a branch line 74. In the coupling line 73, a third switching element 83 is provided between the branch line 74 and the first hydraulic line 71. In the coupling line 73, a fourth switching element 84 is provided between the branch line 74 and the second hydraulic line 72.

All switching elements 81 to 86 are connected to a control device (not shown). The control device can be connected to or integrated into a control or regulating unit (also not shown) of the entire molding machine 2 in accordance with signal technology. Via the control device, the switching states of the switching elements 81 to 86 (in particular the open position OS and the closed position SS) can preferably be controlled according to a stored program.

In the figures described below, reference numerals are provided in each case only for the components of the respective description which are functionally most important. Otherwise, the description applies to the previously described figures.

Fig. 3 shows an initial position for starting the profile travel. This molded article stroke is performed when the molding die 16 is replaced. Since the newly assembled molding tool 16 usually has different tool heights (measured along the machine longitudinal axis M), the initial position of the tool platens 5 and 14 relative to one another must also be changed. The initial position can be illustrated in terms of the relative position of the pad piston 32 and the pad cylinder 30. In fig. 3, the pad piston 32 is relatively further to the right, i.e. is fitted with a relatively large forming die 16. Now, if the smaller forming die 16 is clamped at a lower die height, the initial position has to be changed in that: the pad piston 32 moves further leftward in the pad cylinder 30. This is illustrated as follows: the position of the pad piston 32 should move from a first initial position a1 (higher mold height) to a second initial position a2 (lower mold height).

In fig. 4 a (first) idle stroke occurs. For this purpose, the first switching element 81 and the second switching element 82 are switched into their closed position SS. The other switching elements (valves) 83 to 86 are located in the open position OS, respectively. The two switching elements (valves) 81 and 82 in the pressure pad sections 71.3 and 71.6 form a shut-off device 8 for interrupting the connection of the pressure pad 3 to the conveying device 6 during this idle stroke. If in this switching position of the switching elements 81 to 86 of the delivery piston 63 of the delivery device 6 the electric drive 10 is moved (to the left), hydraulic fluid is pumped from the first chamber 64 into the second chamber 65. Since the shut-off device 8 interrupts the connection between the pressure mat 3 and the conveying device 6, no movement of the pressure mat 3 and thus of the beam column 4 (yet) takes place. Due to the advantageous geometric embodiment, relatively little hydraulic fluid is pushed into the storage device 9. More precisely, only the quantity delivered via the axially inner partial chamber 67 is now pushed into the storage device 9 (since the torus of the second chamber 65 and the axially outer partial chamber 66 are ideally formed identically).

According to fig. 5, a (first) die height adjustment stroke is then performed. For this purpose, the first and second switching elements 82 are switched into the open position OS, while the third switching element 83 is switched into the closed position SS. The other switching elements 84 to 86 remain in the open position OS. As soon as the electric drive is moved (to the right) in this switching position of the switching elements 81 to 86 of the delivery piston 63 of the delivery device 6, on the one hand hydraulic fluid is delivered from the second chamber 65 via the second hydraulic line 72 into the open pressure chamber 34 and, on the other hand, hydraulic fluid is delivered from the closed pressure chamber 33 via the first hydraulic line 71 into the first chamber 64. Accordingly, the pad piston 32 moves leftward in the direction of the second initial position a2 in the pressure pad chamber 31. During this adjustment stroke of the delivery device 6, the differential volume from the reservoir 9 also moves into the opening pressure chamber 34.

This process (idle stroke and adjustment stroke) can be repeated according to the distance the beam column 4 has to move due to the changed mould height.

Accordingly, a further (second) idle stroke is shown in fig. 6. As in fig. 4, the shut-off device 8 is activated again to interrupt the connection of the pressure mat 3 to the conveying device 6. When the connection of the pressure pad 3 to the delivery device 6 is interrupted by the shut-off device 8, a connection line 70 connecting the first chamber 64 and the second pressure chamber 5 is opened for delivering hydraulic fluid between the chambers 64 and 65.

Fig. 7 shows a further (second) adjustment stroke. As in fig. 6, in order to carry out the die height adjustment stroke of the pad piston 32 of the pressure pad 3, the first and second switching elements 81, 82 are in the open position OS and the third switching element 83 is in the closed position SS, so that additional hydraulic fluid from the delivery device 6 is delivered into the open pressure chamber 34.

In fig. 8, a second initial position a2 is then reached. The closing unit 12 (and in particular its drive 1) is therefore adapted to the mould height of the newly installed moulding mould 16.

However, with the described drive device 1, not only can a (relatively less performed) mold height adjustment be performed, but also a closing force application can be performed. This is explained in detail below. The switching elements 81 and 82 forming the shut-off device 8 (which are always in the open position OS) are not shown for the sake of simplicity only. If necessary, the switching elements 81 and 82 may also be omitted entirely.

In fig. 9 is shown diagrammatically: how to perform the compensation of the position tolerance when closing. (in the case of a positive connection between the beam column 4 and the locking device 17 (beam column nut 17), compensation of the positional tolerances of the groove geometry is carried out.) the third shift element 83 is in the closed position SS, while the other shift elements 84, 85 and 86 are in the open position OS. The switching elements 81 and 82 forming the shut-off device 8 are not shown. When the transport piston 63 of the transport device 6 moves to the left, then the pad piston 32 moves to the right, so that the sides of the channel geometry of the beam column 4 rest on those locking devices 17. In this stroke, a relatively large volume is required (beam column 4 adjusted by, for example, 2mm) if the forces to be overcome (friction between movable die platen 5 and machine base 13; inertia forces at hydraulic fluid pressures of 20 to 40 bar; friction between movable die platen 5 and beam column 4; friction between pad cylinder 30 and pad piston 32) are relatively small.

Fig. 10 shows the switching position during the building up of the closing force. The sixth shift element 86 in the first branch 71a of the feed section 71.6 of the first hydraulic line 71 is in the closed position SS. The other switching elements 83 to 85 are in the open position OS. By using only a small cylinder surface of the delivery rod 68 in the axially inner partial chamber 67, by means of the switching position when moving the delivery piston 63 to the left, a smaller force acts on the delivery piston 63 than when using the entire piston surface. If the transmission piston 63 moves to the left, in this switching position a closing force is built up by compressing the hydraulic fluid to approximately 300bar, the pad piston 32 and the beam column 4 moving further to the right together with the pad piston. In this "stroke" (the beam 4 is hardly moving any longer, said beam extending due to the pressure loading), a relatively small volume is required (compression of the hydraulic fluid from about 20bar to about 300bar) at relatively large forces (about 7 to 15 times when compensating for positional tolerances).

As soon as the building up of the closing force is completed, the switching elements 83 to 85 are also switched into the closed position SS. The pressure in the closing pressure chamber 33 (and in the first hydraulic line 7 up to the switching elements 85 and 86) is therefore blocked, so that the loading of the delivery device 6 (delivery piston 63, drive rod 69 and electric drive 10) is as low as possible (see fig. 11).

The sealing occurs before the closing force is actually reduced as shown in fig. 12. For this purpose, the switching elements 83 to 85 are switched into the open position OS again. At the same time, the delivery piston 63 moves to the left (in the direction of the build-up closing force).

Subsequently, the closing force build-up is performed according to fig. 13. For this reason, the switching elements 83 to 86 remain in the same positions as in fig. 12. However, the transfer piston 63 of the transfer device 6 is moved to the right (in the direction of decreasing closing force) so that on the one hand hydraulic fluid is transferred into the opening pressure chamber 34 and on the other hand hydraulic fluid is transferred out of the closing pressure chamber 33.

In fig. 14, the beam column 4 is repositioned. For this purpose, the third switching element 83 is in the closed position SS. The other switching elements 84 to 86 are in the open position OS. By moving the delivery piston 63 to the right, the pad piston 32 moves to the left.

In fig. 15, the initial position (a1 or a2, depending on the mold height) is reached again.

Fig. 16 shows how an increased opening force is applied and tearing by means of the pressure pad 3 can be carried out if necessary. (this can also be done with a low force by means of an additional quick stroke device.) for this purpose, only the fourth switching element 84 is switched into the closed position SS. The other switching elements 83, 85 and 86 are in the open position OS. To assist the opening (movement of the pad piston 32 to the left), an additional pressure loading takes place in the opening pressure chamber 34 when the delivery piston 63 moves in the direction of decreasing closing force (to the right). In this stroke, a relatively small volume (compression of the hydraulic liquid to 20bar to 40bar) is applied at a relatively small force (compression of the hydraulic liquid to 20bar to 40bar), so that an increased opening force (for example about 260kN, depending on the construction size) is achieved. By means of the switching positions of the switching elements 83 to 86, the annular surface of the delivery piston in the axially outer partial chamber 66 acts as an effective piston surface when the delivery piston 63 is moved to the right.

In fig. 17, the conveying device 6 is designed as a (not according to the invention) single-stage force converter. That is, the first pressure chamber 64 is formed as a one-piece (annular in cross section) chamber. Only one line in the form of a first hydraulic line 71 is connected to the first pressure chamber 64. The shut-off device 8 is formed here by a first switching element 81 in the pressure pad section 71.3 of the first hydraulic line 71 and by a second switching element 82 in the pressure pad section 72.3 of the second hydraulic line 72. A third switching element 83 and a fourth switching element 84 are arranged in the coupling line 73. The storage device 9 is connected to a coupling line 73. The coupling line 73 forms a connecting line 70 together with the delivery section 71.6 of the first hydraulic line 71 and the delivery section 72.6 of the second hydraulic line 72. The basic function of the conveying device 6 in the form of a single-stage force converter is the same as a two-stage force converter, so reference can be made to the above-described embodiment. The difference is that, due to the single-stage design of the conveying device 6, a relatively long stroke and a large installation space are required thereafter, or alternatively a large force acts on the conveying device 6 or the electric drive 10.

Fig. 18 shows a cross section of an embodiment in which the delivery device 6 is integrated into the pressure mat 3. In particular, a cavity is formed in the pad piston 32, wherein, for example, a delivery piston 63 of the delivery device 6 is movably supported in the pad piston 32. The switching elements 81 to 84 and the associated lines of the hydraulic line system 7 are also formed in the pad piston 32. In fig. 18, the conveying device 6 is designed as a single-stage force converter, similar to that in fig. 17.

Fig. 19 shows an embodiment in which the delivery device 6 is also formed or arranged in the pad piston 32, but the delivery device 6 is formed as a two-stage pressure transducer.

All reference numerals in fig. 18 and 19 denote the same components as all reference numerals in other drawings and embodiments. The function of the individual components of the drive 1 according to fig. 18 or according to fig. 19 is similar to the previously described variants.

List of reference numerals:

1 drive device

2 Forming machine

3 pressure pad

30 cushion cylinder

31 pressure cushion chamber

32 pad piston

33 closed pressure chamber

34 open pressure chamber

4 beam column

5 Movable die platen

6 conveying device

61 conveying cylinder

62 transfer chamber

63 delivery piston

64 first chamber

65 second chamber

66 axially outer subchambers

67 axially inner subchamber

68 conveying rod

69 driving rod

7 hydraulic pipeline system

70 connecting pipeline

71 first hydraulic line

71.3 pressure pad section

71.6 conveying section

71a first branch line

71b second branch

72 second hydraulic line

72.3 pressure pad section

72.6 conveying section

73 connecting pipeline

74 branch line

75 branches

76 branch

77 branch

8 cutting device

81 first switching element

82 second switching element

83 third switching element

84 fourth switching element

85 fifth switching element

86 sixth switching element

9 storage device

10 electric driver

11 injection unit

12 closed unit

13 machine base

14 fixed die platen

15 end plate

16 forming die

16a mold half

16b mold half

17 locking device

17a half shell

17b half shell

18 drive rod

SS closed position

OS open position

Longitudinal axis of M machine

A1 first initial position

A2 second initial position

Claims (27)

1. A drive device (1) for a forming machine (2), the drive device having:

-at least one hydraulically driven pressure pad (3) via which a beam column (4) or a movable mould platen (5) of the forming machine (2) can be moved to apply a closing force;

-a conveying device (6) for conveying hydraulic fluid, wherein the conveying device (6) has a conveying cylinder (61), a conveying chamber (62) which is formed in the conveying cylinder (61) and is filled with hydraulic fluid; and a delivery piston (63) movable in said delivery chamber (62); the delivery piston (63) divides the delivery chamber (62) into a first chamber (64) and a second chamber (65); and

a hydraulic line system (7) filled with hydraulic fluid, via which the delivery device (6) is connected with the pressure pad (3),

characterized in that the conveying device (6) is designed as a two-stage force converter, wherein the second chamber (65) is designed in two parts.

2. The drive arrangement according to claim 1, wherein the second chamber (65) has an axially outer sub-chamber (66) which is annular in cross-section and an axially inner sub-chamber (67) which is separate from the axially outer sub-chamber.

3. The drive device according to claim 1, characterized in that a shut-off device (8) is provided for interrupting the connection of the pressure pad (3) with the conveying device (6), and a connection line (70) is provided for connecting the first chamber (64) with the second chamber (65) for conveying hydraulic fluid between the first chamber (64) and the second chamber (65) when the connection of the pressure pad (3) with the conveying device (6) is interrupted by the shut-off device (8).

4. The drive device according to claim 1, characterized in that the pressure pad (3) has a pad cylinder (30), a pressure pad chamber (31) which is formed in the pad cylinder (30) and is filled with hydraulic fluid, and a pad piston (32) which is movable in the pressure pad chamber (31), the pad piston (32) dividing the pressure pad chamber (31) into a closing pressure chamber (33) and an opening pressure chamber (34).

5. The drive arrangement according to claim 4, characterized in that the hydraulic line system (7) has:

-a first hydraulic line (71) connecting the closed pressure chamber (33) of the pressure pad (3) with the first chamber (64) of the delivery device (6);

-a second hydraulic line (72) connecting the opening pressure chamber (34) of the pressure pad (3) with a second chamber (65) of the delivery device (6); and

-a coupling line (73) connecting the first hydraulic line (71) and the second hydraulic line (72).

6. The drive device according to claim 5, characterized in that a first switching element (81) is provided in the first hydraulic line (71) between the branch (76) leading to the coupling line (73) and the closing pressure chamber (33), and/or a second switching element (82) is provided in the second hydraulic line (72) between the branch (75) leading to the coupling line (73) and the opening pressure chamber (34).

7. The drive device according to claim 6, characterized in that, for carrying out a delivery device idle stroke of a delivery piston (63) of the delivery device (6), the first switching element (81) and the second switching element (82) can be brought into a closed position (SS), wherein the first switching element (81) and the second switching element (82) together form a shut-off device (8).

8. The drive device according to claim 6, characterized in that a third switching element (83) is provided in the coupling line (73).

9. The drive device according to claim 8, characterized in that, for performing a die height adjustment stroke of a pad piston (32) of the pressure pad (3), the first switching element (81) and the second switching element (82) can be brought into an open position (OS) and the third switching element (83) can be brought into a closed position (SS).

10. The drive arrangement according to claim 4, characterized in that the pressure cushion chamber (31), the delivery chamber (62) and the hydraulic line system (7) form a closed hydraulic circuit.

11. The drive arrangement according to claim 1, characterized in that the hydraulic line system (7) is connected with a storage device (9).

12. The drive arrangement according to claim 8, characterized in that in the region of the coupling line (73) the hydraulic line system (7) is connected with a storage device (9), the storage device (9) being connected with the coupling line (73) via a branch line (74) branching off from the coupling line (73), wherein the third switching element (83) is provided in the coupling line (73) between the branch line (74) and the first hydraulic line (71), and a fourth switching element (84) is provided in the coupling line (73) between the branch line (74) and the second hydraulic line (72).

13. The drive arrangement according to claim 5, characterised in that the second chamber (65) has an axially outer subcavity (66) which is annular in cross-section and an axially inner subcavity (67) which is separate from the axially outer subcavity, the first hydraulic line (71) having a first branch line (71a) and a second branch line (71b), wherein the first branch line (71a) is connected with the annular axially outer subcavity (66) and the second branch line (71b) is connected with the axially inner subcavity (67).

14. The drive arrangement according to claim 13, characterized in that a fifth switching element (85) is provided in the second branch (71b) and a sixth switching element (86) is provided in the first branch (71 a).

15. The drive device according to one of claims 1 to 14, characterized in that the conveying device (6) can be driven by an electric drive (10).

16. The drive device according to claim 15, characterized in that the delivery piston (63) is movable relative to the delivery cylinder (61) by means of the electric drive (10).

17. The drive device according to claim 1, characterized in that the drive device (1) is a drive device for an injection molding machine.

18. The drive device as claimed in claim 5, characterized in that the first switching element (81) is used to carry out a conveying device idle stroke.

19. The drive device as claimed in claim 5, characterized in that the second switching element (82) is used to carry out a conveying device idle stroke.

20. The drive device according to claim 5, characterized in that in the region of the coupling line (73) the hydraulic line system (7) is connected with a storage device (9).

21. The drive of claim 11, 12 or 20, wherein the storage device is a bladder reservoir.

22. The drive device according to claim 16, characterized in that the delivery piston (63) is linearly movable relative to the delivery cylinder (61) by means of the electric drive (10).

23. A molding machine (2) having a drive device (1) according to any one of claims 1 to 22.

24. Moulding machine according to claim 23, characterized in that it has an injection unit (11) and a closing unit (12), wherein the closing unit (12) has a machine base (13), a stationary mould platen (14) connected to the machine base (13) and a mould platen (5) movably supported on the machine base (13); the movable mold platen (5) is drivable by the drive device (1).

25. The molding machine according to claim 24, characterized in that the closing unit (12) has four beam columns (4) which run through the stationary mold platen (14) and the movable mold platen (5), the pressure pad (3) having a pad cylinder (30), a pressure pad chamber (31) which is formed in the pad cylinder (30) and filled with hydraulic fluid, and a pad piston (32) which is movable in the pressure pad chamber (31), wherein each beam column (4) is connected to the pad piston (32) of one pressure pad (3) of the drive device (1) in each case.

26. The molding machine according to claim 24, characterized in that the closing unit (12) is constructed without a beam column, the pressure pad (3) having a pad cylinder (30), a pressure pad chamber (31) which is constructed in the pad cylinder (30) and is filled with hydraulic fluid, and a pad piston (32) which is movable in the pressure pad chamber (31), wherein the pad piston (32) is connected with the movable mold platen (5) and the pad cylinder (30) is connected with an end plate (15) of the closing unit (12) which is fixed to the machine base (13) or is constructed in the end plate (15).

27. The molding machine according to claim 23, characterized in that the molding machine (2) is an injection molding machine.

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