JPS6144512A - Weight balance controller - Google Patents

Abstract

PURPOSE:To balance weight without causing a shock, through a weight balance controller for a tool or the like, by supplying pressure oil to a bearing hydraulic cylinder on the basis of the difference between a standard weight signal and a detection signal for bearing pressure for a newly mounted article. CONSTITUTION:When a workpiece in a balanced weight state is replaced with a heavier workpiece W2, the oil pressure in a hydraulic cylinder 50 is heightened by the quantity of the increase in weight. The oil pressure in the cylinder 50 is detected at 49 to generate a signal voltage. A comparator 32 compares the signal voltage with a standard weight signal voltage from a standard weight setting unit 30 to determine the difference between the compared signal voltages. The difference is applied to an oil pressure switch 38, which acts to operate a pressure reduction valve 42 so that oil pressure corresponding to the difference is delivered from a hydraulic pump 48 to the cylinder 50. As a result, oil pressure for bearing a table 54 and the workpiece W2 is increased to balance weight. Weight balance is thus achieved quickly without causing a shock.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a weight balance control device, and more specifically, in a machine tool, preferably a machining center, when a spindle head, a tool, or a workpiece is selectively held via a cylinder, The system is configured to supply pressure fluid to the cylinder corresponding to the weight change caused by replacing the head, etc., to prevent the generation of overload in the cylinder due to the replacement action, and to quickly ensure a new weight balance. The present invention relates to a weight balance control device.

Machine tools, such as portal type machining centers, have traditionally had a hydraulic cylinder installed at the top of the column, and a rod extending from the hydraulic cylinder suspends and holds the spindle head, workpiece, tools, or a table with a pallet attached. configuration has been adopted. In this case, the weight of the table itself and the weight of tools, workpieces, etc. mounted on the table are added to the hydraulic cylinder, and the weight is balanced.

A composite machining center with such a configuration is shown in FIG. Work machine tool 2 of this machining center 2
In A, a guide member 6.6 is disposed on the upper part of the base 4, and a column 8 is displaceably mounted to this guide member 6.6. That is, the column 8 can be displaced on the guide member 6.6 in the direction of arrow A by a ball screw 12 rotating on the guide member 6.6 under the driving action of the motor 10. A hydraulic cylinder 14 is mounted on the top of the column 8, and a servo motor 16 is mounted adjacent to the hydraulic cylinder 14.

A rotating shaft (not shown) of the servo motor 16 is connected to the ball screw 18 in this case.

The hydraulic cylinder 14 suspends and holds the table 20 by its cylinder rod (not shown), while the ball screw 18 supports the table 20 under the rotational drive of the servo motor 16.
can be displaced in the direction of arrow B. A pallet 22 is removably attached to this table 20, and the pallet 22
Further, a work 24 is attached to 2.

On the other hand, a spindle 26 having a cutting tool 28 attached to its tip is attached to the front side of the workpiece machine tool 2A in the figure, and the spindle 26 is held movably in the vertical direction (indicated by an arrow). A tool machine tool 2B is provided. The tool machine tool 2B includes a column 29, and this column 29 moves forward and backward in the direction of the arrow. Therefore,
By displacing the spindle 26 in the direction indicated by the arrow and adjusting its height to face the workpiece 24 and working together with the machine tool oil 2B, the tool 26 will perform a predetermined cutting operation on the workpiece 24.

Therefore, in such a configuration, the hydraulic cylinder 14
The weight of the table 20, the pallet 22 and the workpiece 24 attached to the table 20 is added to the table 20, and a balance is maintained between the oil pressure in the cylinder 14 and the weight of the table 20, etc., and the ball screw 18 is The position of the table 20 is established under the action of rotation.

However, as is well known, this type of machining center 2 is required to cut various workpieces. Therefore, it goes without saying that there are cases where the work itself or the work and the pallet holding it are replaced together.

However, the weight of all types of workpieces and pallets is not constant, and therefore, the weight suspended by the hydraulic cylinder 14 changes each time the workpiece or pallet is replaced. In other words, the total weight of the table, pallet, and workpiece suspended by the hydraulic cylinder 14 will change each time they are replaced, and especially if the weight suddenly increases at the time of replacement, it will try to balance it. A considerable impact will be applied to the hydraulic cylinder. Eventually, this impact slightly disturbs the positioning of the table 20 relative to a new workpiece, etc., making it difficult to ensure accurate and quick positional adjustment of the table. Moreover, over time, the accuracy of the machining center itself becomes excessively low, which on the other hand becomes a remote cause of shortening its service life. Moreover, it goes without saying that a similar phenomenon occurs when the weight changes due to changes in the attachment of various tools and attachments on the tool machine tool 2B side.

Therefore, as a result of intensive research and efforts, the present inventors have determined that the pressure oil supplied from the hydraulic pump to the cylinder installed at the top of the column constituting the workpiece machine tool 2A is at a predetermined pressure. When the weight of the workpiece, pallet, etc. to be replaced changes, pressure oil corresponding to the change is supplied to the cylinder via a pressure reducing valve consisting of a proportional solenoid valve. If the structure is such that the workpiece, etc. is held after the newly set hydraulic pressure, a suitable weight balance between the hydraulic cylinder and the workpiece, etc. to be replaced can be quickly ensured. It has been found that the above-mentioned inconveniences can be eliminated.

Therefore, an object of the present invention is to supply pressure oil corresponding to the weight change to a hydraulic cylinder in advance when a workpiece, pallet, etc. to be replaced causes a change in weight in a machine tool, etc.
The object of the present invention is to provide a weight balance control device in which a new weight balance can be established between a workpiece or the like and the hydraulic cylinder without any impact.

In order to achieve the above object, the present invention includes: a hydraulic cylinder for supporting a target article; a pressure detector disposed in the hydraulic cylinder to detect hydraulic pressure related to a newly attached target article; a standard weight setting device that stores the standard weight of the target article and outputs a signal related to the weight of the target article to be replaced as an electric signal; and a signal from the pressure detector and a signal from the standard weight setting device. A comparator that compares and outputs the deviation signal, and a proportional electromagnetic type that receives the deviation signal from the comparator via an amplifier, adjusts the valve opening, and sends a predetermined amount of pressure oil to the hydraulic cylinder. It is characterized in that it includes a pressure reducing valve and a hydraulic pump that supplies predetermined pressure oil to the pressure reducing valve.

Next, preferred embodiments of the weight balance control device according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2, reference numeral 30 indicates a standard weight setting device, and the output side of this standard weight setting device 30 is connected to one input side of a comparator 32. In FIG. The other input side of the comparator 32 is connected to the output side of an amplifier 36 via an analog signal memory 34.

Therefore, the output side of the comparator 32 is connected to a hydraulic pressure switching device 38. The hydraulic switching device 38 is substantially the amplifier 4
0 and a proportional electromagnetic relief pressure reducing valve 42 connected to its output side. The input port of this pressure reducing valve 42 is connected to the discharge side of a pump 48 which feeds pressure oil under a predetermined pressure from a tank 46 by a motor 44, and the output port of the pressure reducing valve 42 is connected to one side of a balance hydraulic cylinder 50. Connected to input boat. In this case, a pressure detection element constituting a pressure detector 49 is placed facing the hydraulic cylinder 50, and the output side of this pressure detector 49 is connected to the amplifier 3.
Connect it to the input side of 6. A cylinder rod 52 of the hydraulic cylinder SO suspends a table 54 that holds an object to be controlled, such as a spindle head, a workpiece, and a tool, and the table 54 is threadedly engaged with a ball screw 56 .

The ball screw 56 can be rotated by a servo motor 58. Note that reference numeral 60 in the figure indicates a relief valve connected to the discharge side of the pump 48.

The weight balance control device according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

First, the workpiece W1 held by the table 54 is replaced from a state in which the hydraulic cylinder 50 and the table 54 are balanced, and the workpiece W2 is replaced with a workpiece W2 that is heavier than the previous workpiece. do. In this case, when a new workpiece W2 is mounted, the hydraulic pressure within the hydraulic cylinder 50 increases due to its increased weight. This cylinder internal pressure is detected by a pressure detection element, then introduced into a pressure detector 49 and converted into an electrical signal. The amplifier 36 receives the output signal from the pressure detector 49, amplifies it, and outputs it to the memory 34. The output signal of memory 34 is introduced into one input terminal of comparator 32. On the other hand, an analog signal related to the standard weight of the workpiece W2 to be replaced is derived from the standard weight setting device 30, and this analog reference signal and the signal from the memory 34 are compared by the comparator 32, and the deviation signal is is introduced into the hydraulic switching device 38. The deviation signal is substantially introduced into an amplifier 40, which supplies an output voltage commensurate with the deviation signal to a pressure reducing valve 42 with proportional electromagnetic relief to adjust the opening degree of the pressure reducing valve. As a result, the hydraulic pump 48
The flow rate of the pressure oil is controlled, and when the weight increases, a flow rate commensurate with the opening degree of the pressure reducing valve 42 is sent to the hydraulic cylinder 50, and a new workpiece W2 is supported by this pressure oil. become.

As the pressure oil in the hydraulic cylinder 50 increases in this way, the value of the output signal from the pressure detector 49 also decreases. in the end,
The value of the deviation signal from the comparator 32 also decreases, and the opening degree of the pressure reducing valve 42 also decreases accordingly. As a result, the weight balance between the hydraulic cylinder 50 and the workpiece W2 is finally achieved.

That is, even if the workpiece is replaced with the workpiece W2, the excessive weight thereof will be sufficiently carried by the hydraulic cylinder 50 whose pressure increases, and therefore, there is no possibility that an excessive load will be applied to the ball screw 56, for example. After all, there is no possibility of any impact occurring due to the replacement of the workpiece, etc., and a new weight balance is quickly secured.

According to the present invention, as described above, with a simple configuration, it is possible to sufficiently cope with the frequent replacement of tools, workpieces, or spindle heads in machining centers without considering changes in their weight. It is possible to prevent impact from occurring due to an excessive load on the ball drive or hydraulic cylinder at the time of replacement, and to quickly obtain a new weight balance. Therefore, it is possible to obtain a machining center that allows accurate positioning and control over a long period of time.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments, and various improvements and design changes can be made without departing from the gist of the present invention. Of course.

[Brief explanation of the drawing]

FIG. 1 is a partially omitted perspective view of a machining center according to the prior art, and FIG. 2 is a block diagram of a weight balance control device according to the present invention. 30...Standard weight setting device 32...Comparator 34...Memory 36...Amplifier 38...Hydraulic pressure switching device
40...Amplifier 42...Pressure reducing valve 44...Motor 46...Tank 48...Pump 49...Pressure detector 5o...Hydraulic cylinder 52...Cylinder rod 54...Table 56...Ball screw 5
8. Servo motor 60. Relief valve

Claims (1)

[Claims] (1) A hydraulic cylinder for supporting the target article, a pressure detector installed in the hydraulic cylinder to detect the hydraulic pressure of the newly attached target article, and a pressure detector for storing the standard weight of the target article. a standard weight setting device that outputs a signal related to the weight of the target article to be replaced as an electrical signal; and a signal from the pressure detector and a signal from the standard weight setting device are compared and a deviation signal is outputted. a comparator; a proportional electromagnetic pressure reducing valve that receives a deviation signal from the comparator via an amplifier to adjust the valve opening and sends a predetermined amount of pressure oil to the hydraulic cylinder; A hydraulic pump for supplying pressure oil.