EP2786109A1

EP2786109A1 - Method for end machining and machine suitable therefor

Info

Publication number: EP2786109A1
Application number: EP13712217.2A
Authority: EP
Inventors: Matthias Geiger; Robert Räder; Werner Mühlich; Wolfgang Hafner
Original assignee: MAG IAS GmbH Eislingen
Current assignee: MAG IAS GmbH Eislingen
Priority date: 2012-03-23
Filing date: 2013-03-22
Publication date: 2014-10-08
Also published as: BR112014019744A2; DE102012102499A1; DE102012102499B4; WO2013139958A1; CN104335020B; CN104335020A; MX2014009597A; JP2015511022A; RU2014141698A; US20150107069A1; KR20140136460A; BR112014019744A8

Abstract

In order to avoid a subsequent unbalance of the finished crankshaft, rather than the previous transverse offset of the centring bores (geometric balancing), the rotation of the workpiece about the A- and B-axes prior to the introduction of the aligned centring bores (mass centring) is preferred according to the invention.

Description

End machining method and machine suitable for this purpose

I. Field of application

The invention relates to the end machining of workpieces with centric, rotationally symmetrical surfaces such as crankshafts, including the introduction of centering holes in the end-side end faces of the workpiece.

II. Technical background

In the production of crankshafts, the blank produced as a cast or forged part is first of all machined at one end - the so-called pin - and at the other end - the so-called flange, because at these laterally processed end areas, the subsequent processing steps of the main part of the workpiece Attached clamping device. In the context of the end machining, on the one hand, the workpiece must be brought to the correct length, the round outer circumference of the flange and pin machined and introduced into the end faces each have a center hole, depending on the processing step on one side of the crankshaft - possibly together with a bezel - serves to hold the crankshaft in the machine by means of centering tip received therein. There is the problem that the blanks do not always have the exact same shape, but differ because of increasing wear of the cast or forging, more or less pronounced burrs and other irregularities in the original.

However, some workpieces, including crankshafts, are not subsequently machined on their entire surface, leaving unprocessed areas, e.g. on the cheeks to the hub bearings, back. Therefore, the deviations of the blank also affect whether the machined workpiece has an imbalance, how big this is and in which direction it points.

Of course, during machining, attempts are made to eliminate such imbalance by inserting balancing bores or balancing cuts into circumferentially unreachable portions of the workpiece, thereby balancing the workpiece.

However, with a larger existing imbalance, the available space is often insufficient to provide the required number of e.g. To be able to accommodate balancing bores.

However, since the blanks of a batch are generally all designed approximately the same, one knows after the first machined workpieces of a batch, how strong and in which direction a blank and thus the machined crankshaft will be unbalanced and tries this from the outset by taking this into account already at the initial machining of the ends of the crankshaft:

Therefore, the end processing is usually done so far that in a machining center of the crankshaft blank is clamped in a clamping bracket so that the end areas to be processed are accessible. In this clamping - with a stationary, so non-rotating crankshaft - by means of eg driven cup-shaped cutter first by Querverfahrung the cutter to the blank of the blank brought to the correct axial length and then by axially slipping over the potfförm-, rotating cutter, in the Center carries a center drill, made on the corresponding end of the center hole. The inner diameter of this reader is greater than the outer diameter of the end portion of the workpiece. Subsequently, by another cup-shaped cutter whose inner diameter corresponds to the outer diameter of the end portion of the workpiece, machined by slipping over the outer periphery of this end portion. At the same time or by means of a separate tool, the centering hole is also introduced into the end-side end face of the end region.

For the purposes of the present invention, as a Z-direction - roughly the axial direction of the workpiece or the clamping block for the workpiece is defined, and more precisely considered the direction in which the centering holes are introduced.

The driven cutting tools are along the bed of the machine, on which also the vice for the workpiece is fixed, movable in the X and Y directions.

In order to minimize the imbalance detected with the first workpieces of a batch from the outset, the two centering holes are not introduced into the workpiece on the same Z axis, only in opposite directions, but one of the driven tools is moved in the X direction and / or Y-direction to the corresponding tool at the other end of the workpiece slightly offset so that the feared imbalance is compensated. The Zentnerbohrungen and - especially in a common cutting tool consisting of center drill and surrounding cup-shaped cutter - are thus introduced in the Z direction ends to be machined not two mutually aligned, but parallel offset counter-Z directions.

However, this so-called geometric centering has the disadvantage that the workpiece is not held optimally stable during later clamping of the crankshaft, but can run a bit out of round, since in the later processing steps, the workpiece receiving two centering on a common, aligned centering However, the Z-axis lie, the directions of the two center holes in the workpiece but not on a common and aligned center hole axis.

III. DESCRIPTION OF THE INVENTION a) Technical Problem

It is therefore an object of the invention to provide a method by which the disadvantages of the known approach can be avoided and to provide a machine suitable for this purpose, which is less expensive, in particular with regard to the method and is not more expensive than the machine previously used machines.

b) Solution to the Problem This object is solved by the features of claims 1 and 8. Advantageous embodiments will be apparent from the dependent claims. The inventive method is that the centering aligned on one and the same Z-axis, only oppositely directed, are introduced to compensate for the imbalance but previously the workpiece is pivoted about the A and / or B axis, that without the pivoting expected imbalance of the present in this state or better of the finished workpiece is minimized, which is hereinafter referred to as "balance centering".

For this purpose, it is determined how large and in which radial direction the machined first workpieces of a batch have an imbalance and, accordingly, the degree and direction of rotation of the workpiece about the A and B axes is determined. A rotation of the workpiece about its C-axis - which would then allow an additional rotation of the workpiece only about either the A-axis or the B-axis - is usually not possible because the blank in the vise in a very specific, positive fit predetermined by the vise, location is added to the C axis.

Thus, the advantage is achieved that the introduced centering holes are aligned with respect to their direction to each other and thus the workpiece is optimally held at later processing steps and recording centering in these center holes, since the direction of the centering coincides with the direction of the centering. In this case, the pivoting about an axis can be achieved in different ways:

In the simplest case, a pivot pin is sufficient, about which the workpiece, in particular together with the vice holding the workpiece, can be swiveled. Thus, for example, a protruding in the X direction pivot pin for the vise can also be moved in the Y direction in order to save the Y-experience of the tool units can. Another possibility is, for example, to realize a pivoting about the B-axis by the workpiece holding vise is moved differently on two spaced in the Z direction Y-guides. For carrying out the method, a machine is proposed according to the invention, in which the vice with the workpiece received therein is pivotable about the A and / or about the B axis relative to the bed of the machine. Of course, the pivotability is like all other operations of the machine thereby effected by a machine control, in which either the amount of pivoting about the A and / or the B-axis is entered directly, or in the only the size and direction of the imbalance to the Previous workpieces must be entered, and which determines the degree of pivoting of the vise around the A and / or B axis itself.

The pivotability about these axes, for example, about the A-axis, can theoretically be effected differently, for example by the vise about a solid, lying in the direction of the X-axis bearing pin is pivotable.

However, since considerable forces act on the workpiece held in the vise, the vise will additionally or instead rest on and be guided in the Y direction, spaced apart in the Z direction, Y guides. A pivoting about the A-axis is then either about the additionally existing, in particular in the axial center of the vise arranged pivot pin possible or simply in that separately controllable drives for moving the vise along each one of the two Y-guides are present, and the displacement in the Y-direction is different, so that an inclination of the vice to the Z-axis is achieved analogous to a rotation about the A-axis.

Then, however, both a rotatability of the vise on the him on the Y-guides holding guide shoes necessary as well as displaceability in the longitudinal direction Z at least compared to at least one of the guide shoes, since so changes in an inclined position of the distance of the guide shoes. If a pivot pin is not present, the vice is preferably rotatable relative to one of the sliding shoes, but not displaceable in the longitudinal direction. The length compensation is performed only with respect to the other guide shoe during pivoting. Even if the vice is moved with separate drives along the two Y-guides, thereby the vice can also be moved in parallel in the Y direction, ie without pivoting the axial direction of the vice relative to the Z-axis of the machine about the A-axis ,

Similarly, a pivoting about the B axis can be achieved

However, such a realization of the Y-axis in the vice then allows a waiver of the Y-slide in the two tool supports the machine, which are much more complex, since on this Y-slide yes the X-carriage of the support must run. The savings on the machine through tool supports, which have only one X-slide, are thus higher than the extra effort for the realization of the Y-displacement on the vice. The pivoting of the vise about the B-axis can also be realized in different ways, and it can also here to spaced, running in the X direction X-guides - if necessary. On the guide shoes - are used, on which the vise in X. Direction can be moved, and the inter alia, the pivoting of the vise around the B-axis is used, analogous to the pivoting about the A-axis, either with or without existing pivot pin.

However, since it is for the purpose of pivoting to longitudinal movements in the X and Y directions usually only in the 10th millimeter range, it is usually not useful, even the method for realizing the X-axis of the tool supports in the mobility of the vise to relocate. Only in exceptional cases, this will be useful. c) embodiments

Embodiments according to the invention are described in more detail below by way of example. Show it:

1 a, b: a crankshaft as a workpiece with machined ends,

Fig. 1 c: end machining according to the prior art

Fig. 1d: end processing according to the invention Fig. 2a-c: the machine according to the invention

Fig. 3a, b: the vice for the workpiece separately, and Fig. 4a-c: the vise on the bed of the machine.

Figures 1a, b show a crankshaft as a typical workpiece 100, in which the end machining according to the invention is to be applied, at the end portions of the crankshaft 100, namely the so-called pin 105 at one end and the disk-shaped flange 106 at the other end on the other hand, in each case the lateral surface is to be machined, the crankshaft is to be cut to the correct length and in the end faces of pin 105 and flange 106 each have a center hole 102 is to be introduced, as shown in the side view of the crankshaft in Figure 1 b.

In this side view, furthermore, the stroke of the crankshaft 100 can be clearly seen, by which the crank bearings 104 are eccentrically offset with respect to the center bearings 103, connected in each case by cheeks 107.

The other discernible details, such as oil wells, etc., are less relevant to the present invention. FIGS. 2 a to c show, in front view, axial view and top view, a machine tool 1 with which the crankshaft 100 or other similar workpiece delivered as forged or cast blank is machined in the end regions, which are subsequently subjected to precise machining of this workpiece 100 during other processing steps serve in the processing of the middle area.

The machine 1 is to be assigned in principle to the category machining center, because the workpiece 100 is thereby processed in the non-rotating state by means of rotating tools 6, 7.

For this purpose, on the bed 2 of the machine 1, which has an approximately cuboid, upright basic shape and rests on a comparatively larger base plate 23, on the front side of a vice Fixed table 19, which projects from the front of the bed 2 to the front and on which the vice 3 is mounted, which is specifically adapted to the respective workpiece to be machined 100, in this case a specific crankshaft, and accordingly on the vise Table 19 is positioned. The adaptation takes place, in particular, by carrying corresponding clamping jaws 25 for the workpiece 100, which can be better seen in FIGS. 3 a, b.

On the upper side of the bed 2, two tool units 4, 5 run, in that on the upper side Z-guides 18 run, along which the respective Z slide 21 of the tool unit can be moved.

The Z-direction here is the connecting line between the two tool units 4, 5 and thus approximately the axial direction of the workpiece 100 to be machined.

On the front surface of the Z-carriage 21 is along X-guides 12, an X-carriage vertically to the vise 3 and thus the workpiece 100 to and from this movable. In this case, each X-carriage 22 carries, in addition to a tool spindle 16a, b or 17a, b, a tool inserted therein, which can be driven in rotation about the Z-axis.

The relative positioning of the tools 6, 7 to the workpiece 100 in the Y direction can take place in that in the tool units 4.5 see between the Z-slide and the X-carriage each one on the Z-carriage in the Y-direction movable Y. Sled exists. However, according to the invention, the setting in the Y direction on the side of the vice 3 is preferably carried out, as will be explained with reference to FIGS. 4 a to c.

The entire processing performed on this machine is controlled by a central machine control 10, as with all machine tools. As the enlarged view of the vise 3 - in perspective and in front view - the figures 3a, b shows, consists of the vice 3 on the one of two pairs of clamping jaws 25, the workpiece, in this case the crankshaft 100, in each case the last main bearing 103 between them. In addition, the vise 3 in the middle comprises a support 26, on which one of the other main bearings 103 of the crankshaft 100 can rest. The resulting positioning of the crankshaft 100 is a coarse positioning, since the surfaces on which the jaws 25 and the bearing 26 abut the crankshaft 100, are not processed at this time. The three units, on the one hand carry the two jaws 25 and on the other hand, the bearing 26, in the Z direction along racks 24 which are arranged on the upper side of the tensioning table 19, displaceable and terminal choice, in particular form-fitting clamped, and also have a Adjustment in Y-direction and - by choosing the right size of jaws 25 and support 26 and / or by adjustability in the X direction - an adjustment in the X direction.

FIG. 3b shows the machining of flange 106 and pin 105 by respective rotating tools 6, 7:

At the end portion 106, the first tool used 6 is shown: It is a pot-shaped rotating tool 6 in the manner of a pot-milling, in the center of which is a centering drill 8, which is set back from the front of the pot. The inside diameter of the pot is larger than the outside diameter of the end area. First, the workpiece 100 is brought to length by Querverfahrung by means of the cutting of the pot, so the end face milled. subse- ßend the centering hole 102 is introduced by slipping this tool by means of the centering drill 8.

In the next step is by another cup-shaped, rotating tool 7, as shown at the right end of the workpiece 100 on the pin 105, and the inner diameter corresponding to the outer diameter to be machined of the respective end portion of the workpiece 100, by slipping the head over the end portion by the inside of the pot-shaped rotating tool 7, the lateral surface of the respective end region, for example of the pin 105, processed.

Of course, the dimensions of the tools must be adapted to the contours of the workpiece to be produced accordingly. Figures 1c and d show the end portions of a crankshaft 100 to be machined, wherein in Figure 1 c, the machining according to the prior art and in Figure 1 d, the machining is shown according to the present invention: Figures 1 c and d show the workpiece respectively in the ZX-level:

If it turns out in the finished first workpieces 100 of a batch that they have an imbalance in the form of an overweight - in the illustration of Figures 1 c, d -. B. in the upper right portion of the workpiece 100, this has been compensated according to the prior art in the subsequent workpieces characterized in that the right center hole 102, to be introduced with the center drill 9, the distance 15 was offset slightly upwards and the corresponding Lateral surface of the workpiece.

As a result, the imbalance in the ZX plane was lower relative to the connecting line between the two centering holes 102, however, the centering holes 102 were no longer aligned with one another, since these are now parallel lying to each other, spaced Z-axes Z1 and Z2 were, which caused a non-optimal tension of the workpiece and subsequent manufacturing inaccuracies in subsequent recording between aligned points in the next step.

Likewise, an imbalance in the Y-Z plane was minimized by offsetting the center hole 102 in the Y direction.

The problem of non-aligned centering holes 102 according to the invention - see Figure 1 d - thereby avoided that the center drill 8,9 are always on a common, aligned Z-axis Z.

In order to minimize an imbalance in the XZ plane shown in FIG. 1 d, the workpiece 100 is instead slightly pivoted about the B axis, wherein the pivot point may lie in the middle of the longitudinal extent of the workpiece or else at or near one of its end regions, preferably oppositely the position of the imbalance to be eliminated.

In FIG. 1 d, the point of impact of the left centering drill 8 on the left-hand end face on the journal 105 of the crankshaft 100 is selected as the pivot point.

Frequently, in addition to minimizing an imbalance, a pivoting of the workpiece 100 around the A-axis is also necessary analogously in the Y-Z plane.

The pivoting angle as well as the distance 15 in Figure 1 c are greatly exaggerated, because in reality this is pivoting angle of usually less than one degree.

FIGS. 4a, b, c show the manner in which a corresponding alignment of the workpiece 100 takes place in the machine tool 1: For this purpose, the vise 3 - and with it the form-fitting recorded therein crankshaft 100 - slightly opposite the vice table 19 pivotable about the A-axis. This is done in this case by 19 in the tensioning table 19 two Z-direction spaced threaded spindles 27 extend in the Y direction, on each of which - one or - spaced in the Y direction two - spindle nuts 28 are guided so that they do not interfere with the Screw threaded spindle 27, but are moved axially by them.

On the spindle nuts 28 of the vice 3 sits with its underside, for example by means of a respective support block 29 and is fixedly connected to the spindle nuts 28, but limited pivotable about the A-axis. On one side of the vise 3, for example in Figure 4a the right side, the support block 29 of the vise 3 must also be limited in the Z direction slidably relative to the spindle nut 28, because by an inclination of the vise 3 to the Z-direction of the bed. 2 In the case of the machine, the distance between two spindle nuts 28 spaced apart in the Z direction changes.

Instead of the spindle nuts and the threaded spindles and longitudinal guides with running guide shoes are used, in which case the drive along the longitudinal guides must be additionally solved.

The vice 3 can thus be pivoted about a desired angle about the axis A to the Z-axis of the bed 2 of the machine. 1

By synchronously moving the threaded spindles 27, however, the vise 3 can also be displaced parallel to the Z-direction, in this case horizontally, and thereby the Y-axis of the machine can be completely realized by the vise 2, so that the tool units 4, 5 do not have a Y-axis. Need sledges. In addition, if an imbalance elimination in the XZ-level is needed, so z. B. in the basic bodies of the jaws 25 - as best seen in Figure 3b - a height adjustment provided which can be controlled independently of each other for the two jaws 25 and thereby the axial direction with the crankshaft 100 in the desired inclination to the Z- Direction of the machine tool can be brought in the ZX plane.

Also, a rotation of the tensioning table 19 relative to the bed 2 of the machine Ma about the B-axis could cause this, however, is to realize substantially cost Diger.

LIST OF REFERENCE NUMBERS

1 machine

2 bed

3 vice

4 tool unit

5 tool unit

6 tool

7 tool

8 center drills

9 center drills

10 machine control

1 1 Y-guide

12 X-guide

13 guide shoe

14 pivot pins

15 distance

16a, b tool spindle

17a, b Tool spindle

18 Z-lead

19 vise table

20 longitudinal crankshaft

21 Z-slides

22 X-Sch suffered

23 base plate

24 rack

25 jaw

26 supports

27 threaded spindle

28 spindle nut

29 support block Workpiece, crankshaft end face

Center hole center bearing

pin bearings

spigot

flange

cheek

Claims

1. A method for end machining including introduction of a centering bore (102) in workpieces (100) with centric, rotationally symmetrical surfaces, in particular crankshafts (100), wherein

- The workpiece (100) is clamped,

- The workpiece (100) is cut to the clamped, stationary state and

- In the end-side end faces (101) centering holes (102) are introduced in mutually opposing Z-directions, characterized in that

the workpiece (100) before the introduction of the centering holes (102), at the latest in the clamped state, is pivoted about the A-axis and / or B-axis, that the workpiece (100) relative to the common centering axis (Z) of the centering holes (102) has the smallest possible imbalance.

2. The method according to claim 1,

characterized in that

the centering holes (102) in two mutually aligned, opposing Z-directions, the centering axis (Z) are introduced.

3. The method according to claim 1 or 2,

characterized in that

the workpiece (100) by pivoting in this state and / or in the later finished state has the least possible imbalance.

4. The method according to any one of the preceding claims,

characterized in that

the pivoting is achieved in particular about the A-axis by defined different displacement of the workpiece (100), in particular together with a vice (3) along two Z-direction spaced Y-guides (11).

5. The method according to any one of the preceding claims,

characterized in that

the pivoting is achieved in particular about the A-axis by pivoting about an axis extending in the X-direction pivot pin, which is displaceable in particular in the Y direction.

6. The method according to any one of the preceding claims,

characterized in that

the pivoting is achieved in particular about the B-axis by pivoting about a pivot pin extending in the Y direction.

7. The method according to any one of the preceding claims,

characterized in that

the pivoting is achieved in particular about the B axis by relative adjustment of the extending in the X direction workpiece receptacles, in particular the clamping jaws (25) to each other.

8. Machine (1) for end machining including introducing a centering bore (102) in workpieces (100) with centric, rotationally symmetrical surfaces, in particular crankshafts (100), with

a bed (2),

a vice (3) for the workpiece (100),

- on the bed (2) movably arranged tool units (4, 5) with rotationally driven tools (6, 7), including aligned in the Z direction centering drills (8, 9),

a machine controller (10),

characterized in that

the vise (3) is pivotally mounted about the A-axis on the bed (2),

and or either the vise (3) about the B axis pivotally mounted on the bed (2) or extending in the X direction jaws (25) relative to each other in the X direction are adjustable.

9. Machine according to claim 8,

characterized in that

the vice (3) can be moved both differently and synchronously in the Y direction relative to the bed (2) on Y guides (11) which are spaced apart in the Z direction, and the tool units (4, 5) can only be moved in Z direction. and X-direction are movable.

10. Machine according to one of the preceding device claims, characterized in that

the vise (3) rests on the Y-guides (11) by means of guide shoes (13) and the vise (3) is rotatably mounted on the guide shoes (13) and slidably mounted on at least one of the guide shoes (13) ,

11. Machine according to one of the preceding device claims, characterized in that

the vice (3) in the X direction relative to the bed (2) on at least one X-guide (12) is movable.

12. Machine according to one of the preceding device claims, characterized in that

the vise (3) is pivotally mounted on a pivot pin (14) which extends in the X direction or in the Y direction and in particular in the perpendicular transverse direction, ie the Y direction or the X direction, is displaceable.