DE966133C - Grinding machine with automatic shutdown of the table movement - Google Patents

Description

Grinding machine with automatic shutdown of the table movement Die Invention relates to grinding machines and other machine tools in which the. Movements of the table and the feed of the tool are controlled hydraulically and at the end of the work process, d. H. when the finished size is reached, in usually automatically by a measuring and control device depending on the workpiece diameter the table is stopped and the tool slide is retracted. Because the end a work process; especially with an automatic measuring circuit, such as it is used more and more in modern, fully automatic grinding machines., does not always coincide with that end position of the table which is required for the workpiece change, care must be taken that the table still in. the for the. Workpiece change moves to the intended end position. This is particularly important if the measuring device giving the impulse is not connected to the extreme. End of the workpiece is arranged., But more towards the center. In the case of batch delivery to one or both. Everyone must have lifting ends Stroke to be sanded to the end "otherwise a paragraph in the Grinding surface would occur.

Furthermore, for a first-class work result, it is often desirable that a certain number of table strokes be carried out after the delivery has been switched off and the table only then: on the selected one. End of stroke is stopped. In a similar way, there is often also in plunge-cut grinding: one Desired for a certain time after the infeed has been switched off for so-called sparking-out before the grinding carriage is retracted.

It. devices are known with which such a delay the shutdown of the table movement or the retraction of the grinding wheel is achieved can be.

In one of these devices, a piston is supplied with throttled pressurized oil and the movement of the piston mechanically on one with the main control valve connected lever. With this device, the shutdown process takes place but relatively slow: as a result of the slow movements of the rudders The flow of pressure medium to and from the piston is controlled via the control openings of the reversing valve at times strongly throttled so that the reversing process does not occur occurs suddenly; also it is with this device which is independent of the Table movement works, not possible, the table in a certain position, yes not even to stop once in one end position.

In another device, the movement of a table is dependent on the table controlled, reciprocating piston also mechanically on a ratchet mechanism transfer. The number of table strokes after finishing the finishing process can be set until the table movement is switched off, but is not freely selectable, but depending on the number of teeth on the ratchet wheel and their divisibility by I, 2, 3, 4, 5 etc., as this ratchet is not automatic. is reset to the starting position, but continues to run.

Both known. Fixtures are for a modern machine tool not suitable as it has been found necessary, firstly, in a particular one To switch the end position of the table, secondly, to switch quickly because the table only remains in its end positions for a relatively short time, and thirdly any To set radio transmission times or excavation numbers.

All three demands. are equipped according to the invention Device met. To ensure the desired sequence of the radio transmission process In the case of a hydraulically controlled machine, the shut-off piston is used for the simultaneous Moving back the grinding carriage and stopping the table movement during longitudinal grinding operated via a delay device in such a way that the table is immediately or only after an adjustable number of strokes or time span - from the end of the actual Grinding process counted - is stopped.

The delay device can be used continuously (for plunge-cut grinding) as well as intermittent, depending on the table movement (for longitudinal grinding) be operated. It preferably consists of a hydraulic piston - delay piston, in a manner known per se via one or more into the pressure medium line placed adjustable throttle devices is acted upon and in its end position Releases control cross-sections for the flow of pressure medium to the shut-off calving.

As soon as shortly before reaching this end position, the inlet control cross-section is only opened by a small gap, unthrottled occurs through this gap Pressure medium under the delay piston, accelerates its movement, what a The result is an enlargement of the gap, so that the delay piston then abruptly reaches its end position. At this moment the pressure medium flows through the exhaust control cross-section in the cylinder of the delay piston, which is suddenly opened as a result under the shut-off piston and moves it quickly to the shut-off position.

In addition to the throttle devices in the feed line to the delay piston are to control its movement during longitudinal grinding in the derivation passage cross-sections arranged, which is coupled to the reversing valve of the table movement or of its Location are dependent and influenced. And that is a. first passage cross-section available, which is coupled to the reversing valve for the table movement and only in the middle layers. This reversing valve briefly flows through the outflowing Return oils permitted. The effect of this passage cross section is such that when Longitudinal grinding only in the table end positions, briefly during reversing a pressure medium outflow from the cylinder of the delay piston is possible.

Another passage cross-section consists of a likewise in the drain line placed locking piston, which is also connected to the reversing valve coupled third control cross section is applied.

This latter control cross-section is of this type in a manner known per se set up that the locking piston only in. One table end position of pressure medium is applied, not in the other end position of the table. It is this z. B. achieved by in the one. End position of the reversing valve this third control cross-section the pressure medium the. Releases passage to the locking piston, so that this opens the drain line blocked by the cylinder of the delay piston. The next time you switch. the table movement remains the locking piston. also locked in the central position of the reversing valve, so that no drainage is possible in this end position of the table. In the second end position of the reversing house the pressure medium can flow out of the locking piston through the control cross-section, so that the locking piston opens the drain line, even if the reversing valve is at following switching is moved through its second central position .. In. the to this second. Middle position of the reversing valve belonging second table end position can be a Outflow. The table movement is only stopped in this end position of the table possible.

As a result of this arrangement. so the return oil drain only in one specified, required for the workpiece change. Table end position released, and the shut-off piston can only be actuated in this table position the other table end position not. When plunge grinding. stands the reversing valve in the middle position, so that both passage cross-sections have no effect stay and the: movement of the delay piston continuously only under the influence the setting of the throttle device in the feed line to the delay piston takes place.

It is well known that in grinding machine construction, hydraulics are any mechanical Moving and switching devices preferred, and all modern grinding machines are. with hydraulic facilities. equipped so that technical progress from purely hydraulic to mechanical. Delay devices by themselves results. With this invention the possibility is given, also on fully automatic Grinding machines. the big ones. Advantages of a purely hydraulically controlled spark-out time apply.

An exemplary embodiment for a hydraulic table drive with a delay device and automatic shutdown of the table movement according to the invention is in the drawing shown in schematic form.

In the case of a grinding machine, the support control lever is actuated A the support control valve B is pivoted, whereby the grinding carriage. steered back, if necessary, the table movement is stopped during longitudinal grinding and others, for example for an automatic. Sequence of the workpiece change required control movements be initiated.

During the work process during plunge-cut grinding, i.e. without table movement, in which the grinding slide is controlled back immediately after the finished dimension has been reached should be, i.e. without sparking, is: the cock 2 in the one with a dash-dotted line Line indicated location. When the finished dimension of the workpiece is reached., by scanning the workpiece, not shown - since known per se - Measuring and control device given pressure medium to line I, which is via the tap 2 immediately passes under the shut-off piston 3. moves this up quickly and through this. in a manner known per se on the: support control lever A and indirectly acts via this on the support control valve B., whereby the grinding carriage moves back immediately and line I is connected to return oil ..

Is used during plunge-cut grinding after the measuring and control device has responded with pressure medium impulse in line I a spark-out time is desired or should be Longitudinal grinding with or without sparking the table. automatically at a certain end shut down. the cock 2 must be pulled out with the. Lines drawn, stand in a horizontal position. In this case, the pressure medium goes out of the line I didn't immediately about that. Tap 2 under the shut-off piston 3, but through the Throttle opening 6 and the line 4 under the. Delay piston 5 and pushes it according to the speed set at the throttle opening 6 and the above Line 7 outflowing amount of pressure medium more or less rapidly up, up to its lower edge exposes the control cross-sections between lines 8 and 9.

In. the moment at which the control cross-section of line 8, in the throttled pressure medium is to a small. Gap released is, additional pressure medium flows through this gap under the. Delay piston. and accelerates its movement with increasing gap size more and more, so that he finally suddenly reaches its end position, and then suddenly the control cross-section for line 9 is released. and the pressure medium through this line 9 passes under the shut-off piston 3 and quickly moves it into its shut-off position drives.

The return oil displaced by the delay piston 5 via line 7 is via a passage cross-section Io connected to the table reversing valve C as well as a z. B. from a locking piston, the passage or locking position indirectly on a third control cross-section II coupled to the table reversing valve C. is, existing passage cross-section I2 to line 16 out.

The passage cross section Io is set up in such a way that it is only in, his Central position, which corresponds to the central position of the table reversing valve, allows return oil to pass through.

The passage cross-section I2 is acted upon by the control cross-section II, that the locking piston when the table reversing valve C passes through its central position in one direction is in the locked position, while he is passing through it Middle position is in the opposite direction in the passage position.

All passage cross-sections: as well as: lines 7 and I6 are like this dimensioned large that, if necessary, the entire displaced by the delay piston Return oil volume in the time available when switching the table in a single. Switching step can be carried out at once.

In plunge grinding, i. H. when sanding without moving the table If the table reversing valve C is sparked out, it is held in the middle position: in. which the passage cross section I2 is open .. They are then: Lines 7, I6 constantly for the. Passage of the delay piston. displaced return oil free, so that this is continuously under the influence of only the one with the throttle opening 6 set. Speed moved to its end position.

When grinding longitudinally, the table must: to stop, always in the predetermined position; Move to the end position. It will. hence the table reversing valve C from the table reversing E actuated: and it could always be at both ends of the stroke of the table if the Table reversing valve C and at the same time the passage cross-section OK during table reversal Go over the drawn center position, briefly pressurized medium through the, passage, cross-section flow, unless: the further passage cross section 12 would be present. Intended to the shutdown only in a certain table position, z. B. in the drawn If the end position of the table is on the right, the return oil may only overflow in this end position the line 7 can flow away. To achieve this, the table reversing valve is used C coupled to the third control cross-section II, which is when the Table to the right in the position shown in dash-dotted lines. Included the right side of the locking piston 12 is connected to the line 13, the return oil leads. The locking piston 12 takes its drawn under the action of the spring 15 right end position, in: the passage through line 7 to line 16 is released is. When the table now comes into its right end position, the reversing valve will go C under the action of the table reversal E and thus the control cross-sections Io and II over the drawn center position. The locking piston 12 remains during the table reversal in. the drawn. Location; the return oil coming from the line 7 can, so over the line 16 drain. The delay piston can therefore only be used in this position. 5 moves., The lines 8 and 9 released, the shut-off piston 3 lifted and thus the table movement can be stopped.

After the table movement has been reversed, the table reversing valve takes over C under the action of the table control E his second. End position, where he the. Control cross-section II connects to the line 14 carrying pressure medium, so that the locking piston 12 is acted upon by the pressure medium, against the pressure of the spring 15 is moved into its left position and in this position the line 16 shuts off.

At the next table reversal at the left end of the stroke, when the table reversing valve C goes in the opposite direction over its drawn center position again, If the line 16 is through, the locking piston 12 is still shut off, since the one on the right. Side of the locking piston located pressure medium can not escape initially. Only when the control cross section II has been completely reversed Resumed position shown in dash-dotted lines. can do that on the right Side of the locking piston 12 until then. Drain the trapped pressure oil via line I3 and the locking piston. moves under the action of the spring 15 back to its right drawn location. The passage of the lines 7, 16 at. this place is again free. Before reaching this position of the control cross-section II, however, the passage cross-section has Io line 7 has already been closed again. As already described above, at this end of the stroke of the table there is no movement of the delay piston and thus also no shutdown takes place.

Depending on the setting of the throttle device 6 there is a certain one Number of radio strokes until the delay piston 5 releases the line 8 and then the shut-off piston 3 receives pressure medium via line 9 and moves into its upper position is moved. Since only during the reversal in the table end positions, i.e. in the one drawn Middle position of the reversing valve C and the passage cross section Io an oil flow take place via the line 7 and thus the delay piston 5 move upwards can, the line 8 can only be released in table end positions and the shut-off piston up. are moved, so that a shutdown only in table end positions can be done.

If you want to work with longitudinal grinding without additional spark-out strokes, so immediately after reaching. of the finished dimension, the table movement is stopped then tap 2 is drawn in the. Position adjusted so that the cross-section the throttle opening 6 has the largest possible value. That causes in the next after reaching the finished dimension, the following table end position, in which the replacement of the workpiece is provided, the delay piston 5 in a single movement step reaches its end position and immediately the shut-off piston 3 in its shut-off position is brought.

So that the delay piston 5 is back in. the starting position can be reached, the shut-off piston 3 has an annular groove 17, which is in its upper position, i.e. in the switch-off position (grinding support moved back, table movement is stopped, line I carries return oil) the; management 7 connects to the return oil connection 18 and thus the movement of the delay piston allowed in its lower position under the influence of a spring. Since the piston 3 when switching off via the support control valve B, among other things, by the pressure oil of the Line I has switched to return oil, this has the effect that the locking piston I9, the so far under the action of the pressure oil in, the line I was kept above, under. Action of the spring F goes into its lower end position and thus the connection the line 9 establishes with the return oil connection 2o. As a result, when switched on again the shut-off piston 3 can be moved down into its starting position.

Claims (2)

PATENT CLAIMS: I. Grinding machine with an automatic, after an adjustable period of time or number of strokes, from, the termination of the actual Counting the grinding process, the decrease in the grinding wheel and the shutdown the Tischbe, movement causing device using an adjustable Delay piston acted upon by a throttle., Characterized by the. Presence and interaction of the following features: a) in the cylinder of the delay piston control cross-sections for the movement of the switching piston are arranged, the first Released for the passage of pressure medium in the end position of the delay piston are; b) the: end position of the delay piston is below the Effect of by one. initially only a small gap in the inlet control cross-section Unrestricted pressure medium entering under the delay piston suddenly achieved; c.) in the discharge line from the cylinder of the delay piston (5) is one coupled to the table reversing valve (C) and only the pressure medium passage in the middle position of the table switchover valve releasing passage cross-section (Io) for the return oil displaced from the delay cylinder is arranged; d) in. the drain line from the cylinder of the delay piston (5) is another passage cross-section (I2) arranged whose. Passage or blocking indirectly from one with the table reversing valve coupled, third control cross section (II) is dependent. 2. Grinding machine according to claim I, characterized in that the control cross-section (II) in one end position of the table reversing valve (C) allows pressure medium to pass through to block the control cross-section (I2) that in the following. first middle position of the table reversing valve despite the closing of the control cross-section (II) the control cross-section (I2) remains blocked so that in the second end position of the table reversing valve (C) the the. Control cross section. (I2) pressure medium acting on it can flow away, so that the control cross-section (I2) is open, and that the control cross-section remains open in the second central position of the table reversing valve (C), so that the interaction of the three control cross-sections (Io, II and 12) the drain line is open depending on the table reversal when switching over at one end of the table, and is blocked when switching over at the other end of the table. Documents considered .: German Patent No. 756 056; Reprint from the magazine »Werkstattstechnik und Werksleiter«, year 1936, issue 16, »Tasks. and their solutions in grinding machine construction «by Dr.-Ing. G. Schaudt; Publication No. 2oi, Jan. 1938, Unger cylindrical grinding machine PScd / Ultra.