DE2645426C2 - Device for the dimensionally controlled machining of workpieces on honing machines - Google Patents

Description

c) The measuring device (19) acts on an expansion device via a control device (21) mechanism (17, 17aj for the honing tool (14).

d) The control device (21) is designed to switch the expansion mechanism (17, YIa) from rapid traverse to working infeed depending on the measurement result,

e) and for the advance determination of the amount of the work delivery (18,18 ', ISa) of the expansion mechanism (17, i7a) from the switching point (27, 27') to the finished size (22, 22a; depending on the measurement result of the preliminary measurement controllable.

2. Device according to claim 1, characterized in that the control device (21) has a storage device (34) for the duration of the transport of the workpiece from the pre-measuring station to the processing station Has.

3. Device according to claim 1 or 2, characterized in that the measurement is carried out by determining 3s of the rapid traverse feed path (26a) of the honing tool (14a,) until it rests on the workpiece (llaj.

4. A device according to claim 3, characterized in that a sensing or switching element (31) responding to the system of the honing stones (16aJ on the work space to be machined) is provided which triggers the switching from rapid traverse (26a ^ to working position (28a)).

5. Device according to one of claims 3 or 4, characterized in that the rotary drive of the Honing tool (14a,) is switched off during the measurement.

6. Device according to claim 4 or 5, characterized in that a return movement (32) of the expansion mechanism (1 7a) takes place at the switching point before the start of the working delivery (28a).

\ 7. Device according to one of the preceding claims, characterized in that the switching one or a few honing strokes before the workpiece is cut (U, lla;) from rapid to operation.

8. Setup npch one of the preceding Claims, characterized in that a compensation device (35) for compensating the eo Honing tool wear is provided, which depends on the number of machining operations he follows.

9. Device according to one of claims 1 to 8, characterized in that a compensation (, 5 means (35) is provided for the honing tool wear, which is controllable as a function of the measurement result.

10. Device according to one of the preceding claims, characterized in that the control device (21, 2ia) controls the number of processing steps (28, 28 ', 28a ) for an expanding mechanism (17, \ 7a) which is known per se

The invention relates to a device for the dimensionally controlled machining of workpieces on honing machines with the features of the preamble of claim t.

In the case of honing, the infeed takes place, i.e. most of the time Step-by-step expansion of the honing stones or honing linings is relatively slow because it is a Finishing process is involved. But since there is a certain amount of play for inserting the tool has to be, it would take a very long time for the tool to cut with the normal work feedrate This is why honing machines are already equipped with an egg-aisle addition have been proposed that after the introduction of the honing tool into the bore or during external honing the introduction of the workpiece into the tool, the tool expansion up to one Carry out the preset point in rapid traverse and only then switch to the slower working infeed. However, as a result of unequal machining allowances or form errors in the workpieces, switching from Rapid traverse to work delivery often takes place very early, so that it will still take a long time until that Tool starts cutting. Therefore, the total duration of the honing process, especially with automatic Honing machines, significantly increased compared to the time required for machining.

In the case of grinding machines, an automatic changeover from express delivery is already from DE-OS 15 88 927 and 23 28 582 and from FR-PS 11 47 828, the US-PS 24 48 921 and the magazine "technica", 1967, No. 2, pages 119 to 123 became known.

From two articles with the title "Messgesteuertes Honing" in the magazine "technica", 1970, No. 15, pages 1288 to 1297 and no. 17, pages 1431 to 1449 has become known, for honing upstream measuring devices to be used, from which, however, no functions for determining the finished size are derived will. The upstream measuring devices are only there to protect tools with undersize Separate honing tools. To do this, the machine may be switched off.

However, the object of the invention is to provide a device for the dimensionally controlled machining of workpieces To create honing machines that work despite careful use of the honing tools and precise machining can significantly reduce the total time.

However, this object is achieved according to the invention by the features of the characterizing part of claim 1.

In the invention, the diameter of the bore to be machined is thus determined by the preceding measurement or (during external honing) the outer diameter of the workpiece determined by different Machining allowances, form errors or the like can turn out very differently. By the control device, for example an electronic computing, storage and / or counting device, then becomes the expansion mechanism controlled in such a way that it reaches the at the

Measurement approached and only there or shortly before it switches to working infeed will. So it is not uselessly "honed air".

Furthermore, the amount of infeed of the expansion mechanism from the switchover point to the finished dimension controllable by the control device as a function of the measurement result. It depends on the finding assumed that the amount of the service, especially in the case of step-by-step delivery, the amount corresponds to the machining on the workpiece On the one hand, the switching point is determined based on the measurement result and on the other hand, the required delivery amount, for example the number of delivery steps up to to the finished size. In the vast majority of cases, this measurement control alone is sufficient to achieve the finished dimension within to keep the minimum tolerance limits. However, it can, for example, through the use of Workpieces with a non-uniform hardness or because of something else within the machined row of tools with changing properties, it is possible to correct the additions In this case, a re-measuring station could also be used, as is for example in the DE-AS 19 50 112 is described.

Further preferred design features emerge from the dependent claims and the description in connection with the drawing. Embodiments of the invention are shown in the drawing and are explained in more detail below. It shows

F i g. 1 shows a schematic representation of an exemplary embodiment according to the invention,

F i g. 2 shows a diagram of the way the device works over time, using two different examples shown,

F i g. 3 shows a schematic representation of another embodiment of the device according to the invention and

F i g. 4 is a graph of the way in which it works over time the embodiment according to FIG. 3.

In Fig. 1 schematically shows part of a processing line for workpieces 11 which are advanced step by step in the direction of arrow 12. The workpieces 11 have bores 13 which are machined by a honing tool 14. The honing tool is rotated and moved up and down in the usual way, namely by a honing machine 15, the lifting and rotating drive of which is not shown. The honing tool 14 has honing stones or honing linings 16, which are expanded in the honing tool 14, for example, by a customary expansion cone (not shown). The expander cone is actuated by an expanding mechanism 17, which acts on a widening bar 18 presses the 0 £ ΐ \ expanding cone.

The expansion mechanism has an ellbow, which allows a relatively fast and mostly continuous shift the expansion length can cause in both directions and a working infeed that is adjustable can cause gradual movement of the expansion rod in a direction leading to a working delivery of the Honing stones 16 leads. The expansion mechanism can be any known device, for example a mechanical feed device that is driven by an electric motor via a gearbox is or a combined mechanical-hydraulic Feeding device in which, for example, a ratchet mechanism that drives a belt nut, from hydraulic pistons is operated. The rapid traverse can be carried out both hydraulically and mechanically. It can also be described in DE-AS 19 50 112 and shown expansion mechanism can be used. In front of the honing machine 15 (in the tool direction

12 seen) a measuring device 19 is arranged you occupies a mandrel 20, which is in the workpiece bore

13 is retractable and measures its inner diameter before machining. With the measuring device, it can be be any known pneumatic, electronic or mechanical measuring device. One Pneumatic measuring device could have a measuring mandrel with preferably several radial measuring nozzles be formed, from which air is blown. The one in the gap between the mandrel and the workpiece bore Any pressure loss that occurs can then be used as a measure for the corresponding workpiece dimension will. Electronic sensors work with electronic distance sensors. It is preferred if the Measuring mandrel is designed so that it detects the smallest workpiece diameter, for example, too when the bore is conical.

The measuring device 19 is connected to a control device 21 which normally operates electronically and specifically contains the following units:

A computer 33, which from the measurement result, the length of the rapid feed of the expansion mechanism and the number of processing steps required from the switchover point from rapid traverse to work infeed to the finished dimension determined. There is also a memory 34 which ensures that the result of the Measuring process in the honing machine is only used to control the expansion mechanism when the corresponding workpiece is in the honing machine. In the example shown in FIG. 1, where the Pre-measuring station three "workpieces", d. H. Transport steps for the workpiece, arranged in front of the honing machine is, so it is ensured that the result of the measurement just carried out is only three work steps later has its effect on the expansion mechanism 17. It does not matter whether the measurement result or the control signals that have already been determined are stored.

In the control device, a compensation device 35 is also provided, which the influence of wear of the tool is automatically taken into account. For this purpose, the control device can use a counter for the Have workpieces, which causes the expansion mechanism after a specified number of workpieces, the honing stones in order to readjust the wear that has been shown to occur with this number of workpieces. The entire range is preferably shifted, so that the switchover point from rapid traverse is then also is shifted to work delivery and not just the shutdown at the finished size, so that the Working time not extended with increasing stone wear.

However, a compensation device which has a counter for the number of work delivery steps is particularly preferred has or added up the work infeeds carried out in each case. Depending on it a compensation is then initiated at the expansion mechanism 17 in turn.

In the following, with reference to FIG Establishment according to Fig. 1 possible advantageous automatic Working procedure described:

In FIG. 1, the part of the diameter D of the workpiece that is relevant for the machining is plotted at a very high magnification over the time Γ. Here is the

Area 22 the tolerance range within which the finished dimension must be after machining. The lines 23 and 23 'represent the raw dimensions of the workpiece, as indicated by the symbolically indicated sensor 20 is detected. In Fig. 2 two examples are shown, one of which is shown in solid lines and the other is drawn in dash-dotted lines. Accordingly, the areas 24 and 24 'are the Areas of machining allowances on the workpiece before honing.

After the workpiece 11 is clamped and the honing tool 14 with the small diameter 25 The honing stones drawn in has been run into the bore 13, the honing stones 15 begin to expand in rapid traverse along the line 26. Depending on the measurement result of the measuring mandrel 20, which is in the pre-measuring station the rough measure, d. H. the diameter corresponds Line 23 is scanned by the computer via the memory, a switching signal is given that switches the expansion mechanism from rapid traverse to working infeed. This switching point 27 is set by appropriate setting of the control device so that it is a or a few infeed steps in front of line 23, i.e. in front of the raw dimension of the hole. There is thus a soft cutting of the workpiece, which is advantageous for protecting the workpiece and the tool is.

The working infeed then takes place along the line 28, advantageously in small infeed steps. The number of The computer of the control device already had infeed steps based on the measurement result of the measuring device 19 determined. After the determined number of infeed steps, the work infeed is terminated and thus the actual honing process at point 29. Based on the measurement of the raw diameter it was found that the finished size can be achieved by simply counting the infeed steps or metering determine the delivery path extremely precisely.

After the end point 29 of the honing process, the rapid reset of the expansion mechanism is activated automatically along line 30.

In the case of the FIG. 2, the embodiment shown in dash-dotted lines, the process sequence is the same. Reference is therefore made to the description of the previous exemplary embodiment. The reference signs are the same, but marked with a dash.

In this exemplary embodiment, the machining allowance 24 'is significantly greater than in the previous example. Therefore, a switchover from rapid traverse to ArbeitszüsteüuF.g already takes place at point 27 '. Because of of the determined dimension (line 23 '), the computer had determined a significantly larger number of work steps 28', after it has been carried out, the finished dimension in the tolerance range 22 is reached again

Assuming once that the line 23 'represents the largest machining allowance that can occur in practice, one can see from FIG. 2 see how much time is saved during processing. If the switchover point were to be set permanently, ie without previous measurement, it would have to be provided at point 27 '. In the case of workpieces that have a smaller machining allowance, for example the machining allowance 24, the time period L would then be honed empty. The entire time during which the work infeed is effective would then extend from the required dimension 1 1 to the dimension 12 and the total machining time between the retraction and extension of the honing tool from T 1 to Tl. It can be seen that through the Invention a substantial time saving is possible. In addition, it is ensured that both the tool and the workpiece are protected even with a workpiece which, due to an error, exceeds the maximum provided machining allowance. Without measuring control, the tool would move into the material at rapid traverse and suffer damage itself in the process. The workpiece would then probably also be rejected.

The compensation is made by adjusting the expansion rod depending on the number of processing steps 28 made. The compensation amounts per workpiece are very high with modern honing linings

is low, so it is possible to take over without remeasuring to work long distances with automatic compensation. Diamond honing stones can have a service life of Reach 15,000 to 20,000 holes. With a covering height of approx. 1.5 mm, the tool wear is 0.0001 mm per hole, so that with a dimensional tolerance from 3 μιτι to readjustment only every 30 holes needs to be done. As already mentioned, however, the compensation is even more accurate if, as intended, makes the compensation after a certain number of processing steps.

In the embodiment according to FIG. 3 is a honing machine 15a is provided, which is designed essentially the same as the honing machine 15 in FIG. 1. With her however, the honing tool 14a also serves as a measuring device.

For this purpose, a sensing or switching element 31 is provided on the expansion mechanism 17a, which in the exemplary embodiment is a power-dependent switch for driving the rapid traverse. His switching impulse triggers one Measurement of the rapid traverse delivery path by determining the then present position of the expanding rod 18a and is converted into a corresponding signal. The control device 21a uses this signal as a measurement signal and uses it to calculate the work infeed steps required to achieve the finished size.

The working method of the execution according to Fi g. 3 is the following: There is no pre-measuring station. The honing tool 14a is moved into the bore of the workpiece 11a, which is located on the honing machine. The honing tool is not driven to rotate during this measuring operation. Then the expansion mechanism is actuated in rapid traverse or a corresponding continuous gear (line 26a in FIG. 4). When the honing stones 16a are in contact with the inner wall of the bore, the drive needs more power for rapid traverse. This is determined by the threshold switch 31 and a switching pulse is given which, on the one hand, stops the rapid traverse drive and, on the other hand, initiates the measurement of the rapid traverse infeed distance up to the workpiece blank dimension (line 23a). ie the number of delivery steps 28a. However, before the work delivery begins, the delivery is again withdrawn by the small amount 32 and then the gradual work delivery begins. The computer takes this reset amount 12 into account in the necessary number of work steps (in the case shown, two idle strokes are made). During this reset, the rotary drive for the tool is switched on so that the actual honing then begins. By resetting, a soft, workpiece and tool-friendly approach

cutting of the workpiece achieved and it is avoided that the honing tool has to start under load. The switch-off point 29a is then again in the tolerance range 22a. A compensation for the wear and tear of the Honing stones are not necessary because the working and measuring tools are identical.

Instead of the one described in connection with FIG Measuring device can also be used by other measuring devices. For example, the honing tool have separate measuring strips, although this entails additional work. For special purposes however, this may be necessary. The honing tool could also be something other than a mechanical measuring device have, for example, pneumatic measuring nozzles or electronic distance sensors. In this case the measurement could then be carried out before or while the honing stones advanced in rapid traverse will. The rapid traverse could then be blocked again on the basis of the measurement result. It is also possible to use a separate mandrel located at the same station as the honing machine, although the measuring time then extends the total processing time. Except for the threshold switch mentioned 31 other indirect measuring methods in connection with the expansion mechanism are also possible, for example frequency counter on the rapid traverse drive or the like. In the expansion mechanisms, those are mechanical work, best suited for the implementation of the invention because of their proportionality between the drive of the expansion mechanism and the actual workpiece removal is most accurate

A particular advantage of the invention is that the Maßsteuerur.g of the finished size to be honed with very small Bores, blind holes or the like. Can be used particularly well where measuring calibers or others Measuring devices cannot be used or are difficult to use.

For this purpose 2 sheets of drawings

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Claims (1)

Patent claims: 1. Device for the dimensionally controlled machining of workpieces on honing machines with a) a honing tool (14) and b) a measuring device measuring the workpiece (II), which are arranged for measuring the workpiece diameter before machining begins is Mark: