The invention is comprised in the field of vertical mould casting machines, and it has been improved to achieve a production increase as a result of a work cycle time reduction, as well as better compacting of the casting.
Vertical sand mould casting machines comprise a generally rectangular moulding chamber in which the sand is blown through a hopper or bell arranged at the top. Said chamber is closed by means of two closing plates, closed at one end by a front, moving and swinging plate which allows the exit of the moulded casting, while the other end is closed by a rear plate associated to a compacting piston, which is also used to push on the casting and expel it in order to place said casting on the stack of previously produced castings.
The casting is obtained by blowing sand in the chamber, followed by compacting the sand by means of the opposing pushing of the front and rear plates. After this the front plate is opened and swiveled to allow the casting to exit, which is achieved by pushing with the rear plate, extracting the casting from the moulding chamber and placing it against the previously obtained stack of castings.
These types of are described in U.S. Pat. No. 7,007,738 and U.S. Pat. No. 6,092,585. These patents describe vertical mould casting machines comprising a moulding chamber that is closed by a front, displaceable and swinging plate and a rear plate provided at an end of an extraction piston, compacting that of the casting by opposing pressure of both plates. Castings are thus cyclically obtained forming two half-molds and, with the aid of the extraction piston, they are expelled from the moulding chamber such that they are placed against and aligned with one another, forming a stack which will travel along the corresponding work stations.
However, patent EP 1 219 830, describes vertical mould casting machine in which once the sand has been blown into the moulding chamber, the compacting is performed by the front and rear plates due to the opposing drive of two hydraulic cylinders, which push the front and rear plates to form the casting in the moulding chamber.
In the aforementioned Patent EP 1 219 830, the opening, closing and compacting movements are achieved by means of two hydraulic cylinders acting in opposition. The drive of one of the cylinders, in a first direction, displaces the rear plate for compacting and extracting the casting. The other cylinder is operated in a direction opposite to the first cylinder, acting on a rear frame which, through a series of bars, is attached to the front plate, displacing the front plate for compacting and swiveling.
Once the sand is blown into the moulding chamber, the casting is pressed by means of the opposing and simultaneous drive of the cylinder pushing the rear plate and of the cylinder pushing the front plate, thus forming the casting in the moulding chamber.
Then the cylinder of the front plate reverses its operation, causing the longitudinal and outwards displacement of the frame and therefore of the front plate. The cylinder of the rear plate continues its movement aiding the extraction of the casting. After this moment if the displacement continues a cam will swivel upwards pushing on a rod and therefore pushing and swiveling the front plate. This swiveling motion continues until the front plate is in a horizontal position at the top, in which position the casting may be extracted by the pushing action of the rear plate, which plate is driven and displaced longitudinally by the cylinder of the rear plate.
Vertical mould casting machines are also known in which so-called “plunder cylinders”, made up of two cylinders coaxially arranged and displaceable with regard to one another, such that in order to compact the casting both cylinders act simultaneously, whereas to extract the casting one of the cylinders is displaced with regard to the other.
By using hydraulic cylinders as driving devices of the closing plates, good compacting of the casting is obtained, however there are many other drawbacks derived from the use of hydraulic cylinders, such as for example, high maintenance cost, need for large surfaces to place the cylinders, which considerably increases the size of the machine, low pressure in the movements of the cylinders, greater power consumption, etc.
It is therefore advisable to provide a system for driving the closing plates that overcomes all the aforementioned drawbacks without reducing the compacting force.
The object of the present invention is to achieve the displacement of a (front or rear) closing plate and, therefore quicker compacting of the casting, while at the same time seeking quicker swiveling of the front plate and extraction of the casting than what is achieved with purely hydraulic systems.
The invention relates to a drive device for driving a closing plate in a vertical mould casting machine, the mentioned machine comprising displacement means for displacing the closing plate to compact casting and for extracting it from the moulding machine. The displacement means for displacing the closing plate comprise:
The first speed is a slow speed with which a controlled compacting is sought by slowly displacing either the rear plate or the front plate towards the moulding chamber, very precise movements and a large compacting force thus being obtained.
The second speed is a quick speed with which a quick movement for swiveling or extracting the casting, depending on the plate on which the device object of the invention is acting, is sought. In other words, the second displacement with the second speed is intended to quickly swivel the front plate or quickly push the rear plate and thereby quickly extract the casting.
The drive device can be a simple drive device or a mixed drive device. In a simple drive device, the drive means can be at least one motor, whereas the transmission means can be chosen from different options, such as at least one screw-nut or at least one rack-pinion. The need to use one or more motors will depend on the power required by the system. In the same way, the use of one or more nuts-screws or one or more pinions-racks will depend on the needs of each system.
This drive device can be used to drive a rear plate, a front plate or to actuate the two plates. If the drive device is going to be applied to both plates, the plates can have the same transmission means or they can be different. For example, each of the plates can be driven by screw-nut transmission means or by rack-pinion transmission means, or the front plate can be driven by screw-nut transmission means and the rear plate by rack-pinion transmission means, or vice versa.
In the event that the device drives a front plate, the first displacement is configured to compact the casting, i.e., to displace the front plate towards the moulding chamber and the second displacement is configured to swivel the mentioned front plate and aid in extracting the casting. The first and second displacements are in opposite directions.
If the device drives a rear plate, the first displacement is configured to compact the casting, i.e., displace the rear plate towards the moulding chamber and the second displacement is configured to extract the mentioned casting, i.e., to push the casting to the stack of previously obtained castings. In this case, the first and second displacements are in the same direction.
As previously mentioned, the drive device can be mixed and, therefore, the transmission means can comprise first transmission means to transmit the first displacement and second transmission means to transmit the second displacement. As previously indicated, the first displacement is carried out with a first speed, slow speed, and the second displacement is carried out with a second speed, quick speed.
In the same way as in the simple drive, the slow speed serves to transmit power to the closing plate to carry out good compacting and the quick speed allows swiveling the closing plate if the device acts on a front plate, or extracting the casting if the device acts on a rear plate.
The drive means can in turn comprise first drive means for driving the first transmission means and second drive means for driving the second transmission means.
The first and second transmission means can be arranged coaxially. Specifically, the second transmission means can be linked to a first end of the closing plate and the first transmission means can be arranged between a fixed part, which is fixed to the frame of the vertical mould casting machine, and to a second end of the second transmission means. Therefore when the first transmission means are driven, the first displacement with the first speed occurs, i.e., the first transmission means pushing the second transmission means are displaced, causing the closing plate to move towards the moulding chamber, compacting the casting. The second transmission means cause the second displacement of the closing plate with the second speed, i.e., they cause the quick swiveling of the closing plate or the quick displacement of the plate to extract the casting.
The second transmission means can be joined directly to a first end of the closing plate to cause the second displacement. They can also incorporate a frame joined to a first end of the closing plate, such that the movement of the second transmission means displaces the frame, which in turn pushes the closing plate.
The first and second transmission means can be selected from at least one rack-pinion, at least one screw-nut, at least one connecting rod-crank and at least one hydraulic cylinder, whereas the first and second drive means can comprise at least one electric motor.
In a preferred embodiment the first transmission means are a screw-nut and the second transmission means are a rack-pinion. The following options are possible in alternative solutions:
With each of these combinations a drive device is obtained in which the compacting speed and force are optimal.
As previously indicated, the device object of the invention can be used to drive a front plate or a rear plate or both plates.
If the device serves to drive a front plate, the first displacement is configured to compact the casting and the second displacement is configured to swivel the front plate and aid in extracting the casting. In the event that the device uses a screw-nut and rack-pinion drive, the casting is compacted by means of the screw-nut, since the screw provides the necessary force to compact the casting and the front plate is swiveled by means of the rack-pinion which provides high speed.
In the event that the device drives a rear plate, the first displacement is configured to compact the casting, i.e., displace the plate towards the moulding chamber, and the second displacement is configured to quickly extract the casting, i.e., displace and position the casting in the stack of previously obtained castings. If a screw-nut and rack-pinion drive is used, the compacting is carried out by means of the screw-nut and the extraction by means of the rack-pinion.
The drive means can comprise a support, which can serve to support the electric motor.
The first and second transmission means can comprise a frame, which in turn can comprise a support for the drive means.
Also object of the invention is a vertical mould casting machine comprising the previously described drive device.
With the invention a vertical mould casting machine is obtained which presents a series of advantages such as better control of the movements of the plates, smaller size, less power consumption and lower maintenance.
To complete the description being made and for the purpose of aiding to better understand the features of the invention according to a preferred embodiment thereof, a set of drawings is attached as an integral part of said description in which the following is shown with an illustrative and non-limiting character:
In the operating sequence of the rear plate (2) depicted in
As previously mentioned, the front (1) and rear (2) plates could also be driven by different transmission means, i.e., the front plate could be driven by a screw-nut and the rear plate (2) could be driven by a rack-pinion and vice versa.
The operating sequence for a rear plate (2) is depicted in
There could also be coupling means between the rack-pinion (52) and the hydraulic cylinder (821), such that the rack-pinion (52) goes back until contacting with the hydraulic cylinder (821), the coupling occurring and, after that moment, the hydraulic cylinder (821) goes back and drives the rack-pinion to the initial position.
The sequence and positioning in each of the previously described options for a front plate would be the same as that which has been described for the rear plate, the only difference being that the mentioned front plate is swiveled during the quick movement.
It is obvious that the combination of transmission means can be multiple, since the order in the arrangement of the first and second means can vary.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/ES08/00551 | 8/7/2008 | WO | 00 | 2/4/2011 |