INTERNAL MILLING MACHINE

Description

I. Area of ​​application

[0001] The invention relates to a turning-milling machine for machining shafts, in particular crankshafts, by means of a ring-shaped, internally toothed so-called internal milling cutter. II. Technical background

[0002] While the centrally located main bearings on a crankshaft can be machined relatively easily using other machining processes such as turning, this is more difficult for the eccentrically located pin bearings.

[0003] Milling is generally preferred here, either using an externally toothed disc milling cutter or a finger milling cutter with at least one cutting edge on the front, or using the internal milling cutter in focus here, i.e. a ring-shaped milling cutter with teeth on the inner circumference.

[0004] In turn-milling, in addition to the rotation of the milling cutter around the milling cutter axis - as the term already suggests - a rotation of the workpiece around the rotation axis, the Z-direction, is necessary, whereby a rotation of the milling cutter around the circumferential surface to be machined, in the case of a rotationally symmetrical circumferential surface such as a bearing point around the circumferential surface of this bearing point, is achieved.

[0005] So-called internal milling cutters are also known as milling cutters, i.e. ring-shaped milling cutters with cutting edges on their inner circumference, through which the outer circumferential surface of the workpiece to be machined extends.

[0006] There are two basic designs of internal milling machines: 1.Whirling machines: In the so-called whirling machines, which were already in use in the 1980s, the workpiece to be machined, for example the crankshaft, remains stationary during milling and the center of the ring-shaped internal milling cutter completes a revolution around the stationary bearing point to be machined. 2. Internal milling machine with rotating workpiece: The workpiece, in particular the crankshaft, rotates during milling, so it is sufficient for the rotating internal milling cutter to move only in a transverse direction X to the longitudinal direction Z, the rotational axis of the crankshaft—which is defined as the Z direction on all lathes. The transverse movement of the internal milling cutter must, of course, be controlled and coordinated with the equally controlled rotational movement (C-axis) of the workpiece.

[0007] In the following, reference is always made to crankshafts, without limiting the invention to application exclusively with crankshafts. Rather, all other shafts and their peripheral surfaces, particularly those with a circular cylindrical cross-section, can also be machined with the machine according to the invention.

[0008] For the second design in focus here, the machine has the basic structure of a lathe, i.e. with one or preferably two headstocks facing each other, each of which has a tool spindle with a chuck mounted on its front, in which one of the two ends of the crankshaft is clamped and can be rotated in a controlled manner around the axis of rotation, which runs in the Z direction, in coordination with the transverse movement of the internal milling cutter.

[0009] The advantage of the internal milling cutter over an external milling cutter is the smaller transverse dimensions of the machine in the Z direction and, above all, the lower manufacturing costs of the surfaces to be machined, which is related to the smaller number of cutting edges on an internal milling cutter compared to an external milling cutter that can machine the same bearing position.

[0010] In many internal milling machines, e.g. US 7 179 029 B2, the support for the milling unit is arranged laterally offset parallel to at least one headstock and can be moved on Z-guides there, which usually run parallel and also laterally offset to the Z-guides of the headstock, which, however, does not result in optimal stability of the machine.

[0011] It is also known, for example, from US 7 179 029 B2, for both milling machines and lathes, to design the machine bed as an inclined bed, i.e. with a mounting surface sloping from back to front, on which the other components of the machine are fastened, such as the at least one headstock, optionally a tailstock, an additional clamping device and the at least one tool support.

[0012] This allows the operator good access to the individual components, especially during maintenance work or when changing tools, and it also means that chips falling onto this mounting surface quickly slide down from the bed into a separate chip conveyor running approximately in front of the front edge of the bed, so that the time in which the chips, which are particularly hot during milling, can transfer heat to the bed is very short and thus the heating of the bed remains low.

[0013] Furthermore, it is known from US 4525112 for an internal milling machine, the Z-slide with the tool unit can be moved transversely to the longitudinal direction of the machine and the workpiece to such an extent that it is located largely outside the area of ​​the headstock in this direction in order to facilitate a tool change.

[0014] Furthermore, from US 4180359, on which the preamble of claim 1 is based, and the underlying DE 2658970 A1, an internal milling machine is known in which the guides for the Z-slide are not located at a distance from the perpendicular of the center of the spindle chuck to the inclined bed, but directly below it.

[0015] The passage in the Z-slide is enclosed on all sides and not open at the bottom. Both the workpiece headstock and the workpiece counter headstock are fixed in the Z direction.

[0016] Furthermore, US 2012 / 0148351 A1 shows a milling tool specifically designed for internal milling. III. Description of the invention a) Technical task

[0017] It is therefore the object of the invention to provide a machine suitable for the aforementioned turn-milling of a crankshaft with an internal milling cutter, which, despite its simple design and low overall height, offers high stability and thus manufacturing accuracy with good operability and accessibility of all components of the machine. b) Solution to the task

[0018] This task is solved by the features of the claim 1 solved. Advantageous embodiments emerge from the subclaims.

[0019] For the purposes of this application, the directions and planes are defined as follows: Z-direction:

[0020] Direction of the axis of rotation about which the crankshaft clamped in the chuck of the workpiece spindle of at least one headstock is rotated during milling. Transverse plane:

[0021] The plane perpendicular to the Z direction. Mounting surface:

[0022] The surface of the bed on which the milling cutter support is attached. Support surface:

[0023] The contact surface of the bed on the floor. Since the bed's underside is usually not directly resting on the floor, but rather has adjustable feet attached to the underside, the support surface is the area where the lower contact surfaces of all adjustable feet are located. X-direction:

[0024] The transverse direction perpendicular to the Z direction in the transverse plane, which, together with the Z direction, defines the mounting surface of the bed to which the milling cutter support is attached. The mounting surface of the bed does not necessarily have to be flat; it can have steps. However, the X direction is the largest extension direction of the mounting surface after the Z direction, if the mounting surface is designed three-dimensionally. X'-direction:

[0025] Travel direction of the internal milling cutter in the transverse plane by a maximum additional angle of 45° inclined relative to the X-direction. Y-direction:

[0026] The third spatial direction that is perpendicular to both the Z-direction and the X-direction.

[0027] The specified task is achieved in a generic machine - which usually has two headstocks with chucks facing each other - in that in the at least one milling cutter support, the Z-slide is designed as a bridge-shaped, i.e. portal-shaped, portal slide with an inverted U-shape viewed in the Z-direction, and the two free lower ends of the two free-ending legs of the U-shape of this portal slide can each be moved on a first Z-guide which runs in the Z-direction along the bed.

[0028] The space between the legs of the gantry slide is large enough to pass through the workpiece or the chuck or the headstock, depending on the current Z position of the Z slide.

[0029] Furthermore, a cross slide, the so-called X-slide, is mounted on this gantry slide and can be moved in the X' direction along spaced-apart cross guides which are arranged on opposite sides with respect to the axis of rotation of the machine.

[0030] Since the internal milling cutter is rotatably mounted in the cross slide - between the two cross guides - this design results in a very stable and therefore precise mounting and guidance of the internal milling cutter due to the short lever lengths between the guides and the internal milling cutter, which is essential for high machining accuracy of the workpiece.

[0031] In particular, such an arrangement is preferred that - viewed in the Z direction - in a perpendicular dropped from the milling cutter center to the X direction, the base point of this perpendicular, at least during machining, preferably in no regular functional state of the milling machine at all, lies outside the space between the Z guides for the tool support.

[0032] Since the X'-direction, in which the cross slide can be moved, is only offset by an additional angle of at most 45° may be inclined more flatly or steeply, this results in a favorable center of gravity position of the milling cutter support above the machine bed and the overall height of the machine can be kept lower than if the cross slide can be moved, for example, perpendicular to the mounting surface.

[0033] The fact that the machine bed is also inclined, meaning the mounting surface slopes downwards from back to front toward the operator's side, offers further advantages: With sufficient inclination of the mounting surface, the chips falling onto it slide downwards automatically due to gravity, with only a short dwell time on the mounting surface or the cover arranged above it. This reduces the heating of the machine bed.

[0034] If, in addition, the front edge of the mounting surface is arranged at a distance from the underside of the bed, in particular its support surface relative to the base, a chip conveyor can run in the longitudinal direction of the bed, in particular in the Z direction, directly in front of and below this front edge, into which the chips slide and which is a separate component separate from the bed.

[0035] This eliminates the need for recesses in the subfloor, which are often necessary when installing a chip conveyor under a bed with a horizontal mounting surface. Access to the chip conveyor is also significantly improved.

[0036] As a rule, a longitudinal chip conveyor runs in the Z direction, into which the chips fall, and which transfers the chips at one end to a cross chip conveyor, which usually runs horizontally at right angles to the direction of the longitudinal chip conveyor, usually along one end of the bed to the rear and transports the chips, for example, to a collection container.

[0037] The inclination of the mounting surface of the bed from back to front, i.e. the X-direction, has proven to be optimal if this bed angle between the mounting surface and the support surface of the bed is between 40° and 60° is, in particular between 45° and 55°, especially between 48°and 52°. This means that on the one hand, the chips can still slip off due to gravity, and on the other hand, the overall height of the machine is not too great and the center of gravity of the milling cutter support guided on it is not too far forward, thus preventing the machine from being top-heavy.

[0038] The travel direction X' of the X-slide should be better than this X-direction by a maximum of 45°, better additionally by a maximum 30°, better additionally maximum by 15°, better additionally maximum by 5° be inclined to the X-direction to minimize the height of the machine.

[0039] The free inner passage of the internal milling cutter is larger than the cross-section of the circumferential surface to be machined viewed in the Z direction and in particular the total cross-section of the crankshaft to be machined, so that the gantry slide with the internal milling cutter adjusted accordingly in the transverse direction can be moved in the Z direction over the entire extent along the crankshaft passing through.

[0040] Furthermore, the free inner passage of the internal milling cutter is in particular also larger than the outer circumference of the adjacent chuck of the workpiece spindle, so that the internal milling cutter can be moved in the Z direction into the area of ​​the chuck and encompassing it.

[0041] Furthermore, it is also larger than the outer circumference of the workpiece spindle, so that the internal milling cutter can be moved in the Z direction into the area of ​​the workpiece spindle and encompassing it.

[0042] This means that the entire area between the chucks and including the length range of the chucks is freely accessible for clamping a new crankshaft into the machine.

[0043] At the same time, the cross slide with the internal milling cutter should be able to be moved forward and downward along its cross guides so that, for assembly work and especially for changing the internal milling cutter, the internal milling cutter is at the working height of an operator standing in front of the machine, i.e., below the operator's head height. In this change position, the machine's rotation axis should preferably no longer pass through the free interior space, the cutting radius, of the internal milling cutter.

[0044] For the same reason, the milling motor driving the milling cutter, which is attached to the cross slide, is attached to the front of the cross slide with respect to the milling cutter axis, preferably above the milling cutter axis, whereby care must be taken to ensure that the center of gravity of the entire machine, including the bed, is nevertheless located within the base area of ​​the bed when viewed from above.

[0045] The milling motor for driving the milling cutter preferably protrudes from the rear of the X-carriage in the Z direction and extends past the gantry carriage supporting the X-carriage. This results in a particularly space-saving arrangement.

[0046] For the same reason, the X-motor, which moves the X-carriage relative to the Z-gantry, is also arranged in front of the milling cutter axis and preferably above the milling cutter axis.

[0047] The drive force is transmitted from the milling motor to the internal milling cutter via a milling gear, which is arranged in a gear extension that protrudes from the rest of the X-carriage in the transverse plane and, viewed in the Z direction, preferably has no greater width than the rest of the X-carriage.

[0048] Typically, the internal milling cutter is not mounted directly in the X-slide, but is non-rotatably mounted in a rotation unit that rotates with the internal milling cutter. It is a ring-shaped, so-called spoked plate that extends primarily in the transverse plane and has a passage for receiving and non-rotatably securing the internal milling cutter. This spoked plate has spoke-shaped spacers distributed around its circumference in the Z direction, namely, extending backward toward the X-slide. Their free ends are also non-rotatably attached to a rotating ring that runs continuously in the circumferential direction. Only this rotating ring is rotatably mounted in the X-slide by means of a cutter bearing.

[0049] The milling cutter bearing used is preferably a so-called YRT bearing, which is otherwise used for the bearing of horizontally positioned rotary tables in machine tools and which has barrel-shaped or cylindrical rollers.

[0050] The advantage of the spoked plate, and especially the circumferentially spaced spacers, is that the chips falling from either side of the transverse plane of the internal milling cutter can fall between the spacers as they fall toward the X-slide, onto the bed's mounting surface. Because the spoked plate's spacers rotate with the internal milling cutter during milling, they are also thrown down very quickly. This largely prevents heating of the spoked plate and thus the bearings in the X-slide, which benefits the machining accuracy of the entire machine.

[0051] Furthermore, the machine preferably has an additional clamping device to support the crankshaft between the chucks as close as possible to the machining point or even in the area between the two chucks. In this case, the additional clamping device comprises preferably two clamping parts, preferably clamping plates, that can be moved relative to one another. These clamping parts can be pressed radially against one of the crankshaft bearings on either side. Therefore, each of them preferably has a prism-shaped holder on the side facing the workpiece. The contact surfaces of these holders facing the bearing are provided with a sliding coating, preferably with polycrystalline diamond plates (PCD pads).

[0052] For this purpose, a clamping X-slide is guided in the X'-direction or in the X-direction in a controlled manner on a clamping Z-slide, which is guided along Z-guides in the Z-direction on the mounting surface.

[0053] The clamping plates extend in the transverse plane and protrude from the clamping X-slide towards the milling cutter axis and beyond it.

[0054] The two clamping plates can be moved in a controlled manner relative to the clamping X-slide in a transverse direction, preferably in the X'-direction or in the X-direction, in order to carry out the clamping movement.

[0055] The clamping Z-slide runs on Z-guides, which are preferably located - naturally spaced in the transverse direction, preferably the X-direction - between the Z-guides for one or both Z-slides of the tool supports.

[0056] As a rule, such a machine also has, as explained above, a counter-headstock, which must then also be movable in the Z-direction in order to be able to clamp crankshafts of different lengths.

[0057] The counter-headstock, which then preferably also moves along the same longitudinal guides on which the clamping Z-slide runs, in any case on longitudinal guides that are located between the longitudinal guides for one or both milling cutter supports.

[0058] The machine also includes an enclosure that defines the working area, secures it against unauthorized access, and seals it.

[0059] The two sides of the housing, viewed in the Z direction, are constructed from strip-shaped segments in the front view, which, when closed, are closely adjacent to one another in the Z direction. These segments can be moved individually and, due to different, interlocking dimensions - viewed in the Z direction - can also be moved into one another, i.e. into the same Z area, preferably the Z area of ​​one of the workpiece spindles, so that the entire working area between the chucks, including the chucks, is open and accessible.

[0060] In addition, an insertion opening can be provided in the top side of the housing and can be closed with an insertion flap or insertion door, so that an insertion opening can be opened in the top side of the housing for changing the workpiece without moving the segments of the housing in the Z direction. c) Examples of implementation

[0061] An embodiment according to the invention is described in more detail below by way of example. The figures show: figure 1 a: a perspective view of a first design of the machine in a largely closed state, Figure 1 b:the machine of Figure 1 a in the same view without working area cover, in a partial assembly, Figure 1 c: an additional clamping device in individual representation, Figure 2 : a perspective view of a second, non-inventive design of the machine without working area cover, Figure 3 a: a view of a machine not according to the invention, which essentially corresponds to the second design, viewed in the Z direction from the right side according to Figure 2 here, figure 3 b:an enlargement from Figure 3 a, figure 3 c:the in Figure 2 left tool support viewed in Z-direction, in maintenance position, Figure 4a:a front view of the machine, perpendicular to the Z-direction exactly from the front, Figure 4 b:a section enlargement from Figure 4 a.

[0062] The machine shown is built on an inclined bed, i.e. a machine bed 1, the one mounting surface sloping downwards towards the front - the operator side 1 a, on which the other components of the machine are mounted, partly movable in the Z-direction, the main extension direction of the bed 1 on Z-guides 6 away, 16 a, b as best in Figure 1b to recognize.

[0063] The mounting surface 1 a of the bed 1 is - viewed in Z-direction 10 - although graded several times into individual mounting surfaces, the two corresponding Z-guides have 6 a and 6 b or 16 a and 16b supporting mounting surfaces each have a plane with the same inclination, the bed angle 8, opposite the lower support surface 1 b of the bed 1, with which the bed rests on the ground, which is best in Figure 2 or Figure 3 a is recognizable: In full construction, the machine has - as best seen in Figure 2 and Figure 4a , b recognizable - initially in the manner of a lathe a headstock 2, in which one end of a workpiece in the form of a shaft, preferably a crankshaft 100, tensioned and controlled rotatable around the axis of rotation 10, which defines the Z-direction in the workpiece spindle 2 a of this headstock 2 is recorded.

[0064] As in Figure 2 recognizable, is often a counter-headstock 2' available, which is also on the bed 1is mounted so that the workpiece spindles on both sides 2 a mounted chuck 24 are directed towards each other and can clamp one of the ends of the workpiece and rotate it synchronously.

[0065] While the headstock 2 - the one in Figure 1b not shown for reasons of clarity - usually fixed on the mounting surface 1 a of the bed 1 is mounted, the counter headstock 2' - from the Figure 1b only the chuck 24 can be seen - in the Z-direction, i.e. the direction of the rotation axis 10, movable on the two Z-guides running in the Z-direction 16 a, b, in order to clamp workpieces of different lengths in the machine and rotate them in a controlled manner and thus be able to machine them with this machine.

[0066] At the bottom of the bed 1 There are usually support feet29, which in Figure 3 a, and then the lower contact surfaces of these - usually height-adjustable - support feet define 29 first the lower support surface 1 b of the bed 1, and only if such support feet 29 are not present, such as in Figure 2 drawn, the underside of the bed 2.

[0067] In the design of the Figure 2 The machine has two tool supports spaced apart in the Z direction 3 a, b, which have an internal milling cutter on the front side facing each other 5 through whose free inner passage 5 a During machining, the workpiece, usually the crankshaft 100, through which the circumference of the internal milling cutter 5 is processed as described in the Figures 4a , b recognizable.

[0068] In the presentation of the Figure 1bis only such tool support 3 a, which is also possible.

[0069] In Figure 1b the two are outside, i.e. above and below the Z-guides 16 a,b, on the mounting surface 1 a of the bed 1 running Z-guides 6 a,b clearly visible, on which - how better Figure 3 a shows - this one or these two tool supports 3 a,b, which can be moved in the Z direction.

[0070] Figure 1 a shows the machine according to Figure 1b with the movable workspace cover available in the practice 26, which, when closed, closes at least the top and front of the machine, and thus the working space in which the bed 1, Headstock 2, Counter headstock 2', the tool supports 3 a, b and during processing also only in the Figure 4a , bworkpiece shown 100 condition.

[0071] The workspace cover 26 consists of adjacent strips in the Z-direction when viewed from the front or top view 26 a, b, c, which can be moved in the Z-direction along corresponding guides attached to a machine frame supported by the machine bed in such a way that at least two, preferably all, existing strips 26 a, b, c are pushed into each other or one below the other in the same length range of the Z-direction, so that at least the middle working area of ​​the machine - like Figure 4a , B, preferably the entire remaining length range in the Z direction of the machine is open for maintenance or repair work.

[0072] In the present case, in one of the strips 26b, preferably the middle strip in the closing position, a viewing window is incorporated on the front side through which the operator can see the processes in the work area even during processing.

[0073] Furthermore, in the upper side of at least one of the strips - which are approximately angled when viewed in the Z direction - a flap 27 above the axis of rotation 10 which is so large in the Z-direction that when one or more adjacent flaps are opened 27 a workpiece can be lowered from above into the working area of ​​the machine and clamped in the machine without the strips 26 a, b, c of the workspace cover 26 to move in the Z direction from the closed position.

[0074] The Figures 1 a and b also allow the chip conveyor to be 17 recognize: Not only the Figure 1brecognizable recesses with steps in the mounting surface 1 a of the bed 1, but also the Z-guides 6 away, 16 a, b are covered during operation of the machine with covers (not shown), which are partly connected to the components that are movable in the Z-direction, such as tool supports 3 a, b and counter headstock 2 ' and have an essentially flat, diagonally downward sloping upper surface onto which the very hot chips produced during machining fall and slide downwards towards the lower edge of this surface.

[0075] The chip longitudinal conveyor 17 a extends in the Z-direction below this front edge, so that the chips falling from the front edge into the top-open chip longitudinal conveyor 17 a and transported from there to one of its ends and there to a chip cross conveyor 17b, which conveys the chips backwards along one of the front sides of the machine and drops them into a chip collection container (not shown).

[0076] As above all Figure 1 a clearly shows that - viewed from above - at least the chip longitudinal conveyor 17 a completely and the chip cross conveyor 17 b partly within the overall dimensions of the rest of the machine as seen in the plan view, so that the space required for the machine is not increased by the chip conveyors, except for the discharge end of the chip cross conveyor which may protrude backwards beyond the base area of ​​the machine 17 b, the design and projection of which, however, depend on the local conditions at the installation site.

[0077] How best to Figures 2 as well as 3 a, c show, each tool support 3 a,b from a Z-carriage 4 a or 4b, the - in the top view of the mounting surface 1 a viewed - two side parts 4 a 1 , 4 b 1 which extends from the front surface 4 ' of the Z-carriage 4 a or 4 b in Z-direction from the back of the respective Z-carriage 4 a or 4 b and rest with their undersides on one of the Z-guides 6 a,b run, as best in Figure 3 a and the magnification 3 b to recognize.

[0078] The two side parts 4 a 1 , 4 b 1 are triangular or L-shaped when viewed from the side and protrude at or near the front surface 4 ' from the tours 6 a, b upwards, and are at the upper end over a yoke 4 a 2 , 4 b 2connected to each other to form a portal, whereby the tool supports pointing towards each other 3 ba, b directed front surface 4 ' each Z-carriage 4 a or 4 b by the front surfaces of the yoke, which are particularly aligned with each other 4a2 , 4 b 2 and the side panels 4 a 1 , 4 b 1 is formed.

[0079] Perpendicular to the axis of rotation 17 is on the front surface 4' each Z-carriage 4 a or 4 b a cross slide 7 along cross guides 9 a, b, of which the upper 9 a mostly on the front surface 4' in the area of ​​the yoke 4 a 2 , 4 b 2 and the lower one - which is fixed relative to the axis of rotation 10 opposite - along the front surface 4' from one side part 4 a1 to the other side part 4 a 2 runs, i.e. the free space of the portal-shaped Z-slide 4 a or b crosses.

[0080] The one between the upper yoke e.g. 4 a 2 and the lower cross guide 9 b remaining passage must be large enough to at least accommodate the chuck 24 in the Z-direction, better also the adjoining workpiece spindle 2 and / or counter spindle 2 ' and / or the crankshaft 100. This allows the two Z-carriages 4 a or 4 b as far in Z-direction to the adjacent headstock 2 or counter headstock 2' be moved so that the area between the opposing chucks 24 and including at least the Z-area of ​​the clamping jaws of these chucks 24is free to insert a workpiece such as a crankshaft 100 from above or from the front between two chucks 24.

[0081] In this cross slide 7 is the ring-shaped internal milling cutter 5 rotatably mounted, and by moving the cross slide 7 in the travel direction X' the internal milling cutter 5 brought into contact with the outer circumference of the diameter of the workpiece to be machined, and if the diameter is eccentric to the axis of rotation 10 such as the pin bearing of a crankshaft clamped on the main bearing axis in the machine, the transverse movement of the cross slide must be coordinated with the rotary movement of the workpiece 7 in travel direction X'.

[0082] Of course, the free inner passage of the internal milling cutter 5 large enough to at least accommodate the chuck 24in the Z-direction, better also the adjoining workpiece spindle 2 and / or counter spindle 2' and / or the crankshaft 100, as in Figure 1 b 1 shown.

[0083] In the case of Figures 2 , 3a and 3c the travel direction X' runs parallel to the extension direction X of the mounting surface 1 a, viewed in the direction of the rotation axis 10, which does not correspond to the invention. According to the invention, the travel direction X' extends at an acute angle to the extension direction X, which is at most 45°.

[0084] As the Figures 1 b 1 and 2 and the front view of the Figure 4a , b , and best Figure 2 . 1 As can be seen, the internal milling cutter 5 with its free passage 5 a on the outer circumference in an annular spoke plate 15non-rotatably mounted, which in Z-direction in front of the front surface 7' of the cross slide 7 is positioned, and from which spacers are distributed around the circumference 15 b protrude backwards and with a there, opposite the spoke plate 15 rotation ring offset in Z direction 15 c are firmly connected.

[0085] Only this rotation ring 15 c is mounted on its outer circumference by means of a cutter bearing 18 in the cross slide 7 rotatably mounted.

[0086] The circumferentially existing, radially free passages 15 a between the spacers 15 b serve to allow the milling chips reaching the area radially inside the ring of spacers to fall downwards out of this ring, which is due to the circumferential spacers 15b very quickly and with a short residence time of the milling chips on the spacers 15 b occurs.

[0087] Since the internal milling cutter 5 each with a high drive power and therefore a relatively large milling motor 12 required, and the cross slide 7 an X-engine 19 For the displacement in the travel direction X', the arrangement of these electric motors and the additionally required gears must also be selected in such a way that they allow good accessibility for maintenance and repair purposes, do not interfere with machining and, above all, the large and heavy milling motor 12 the position of the center of gravity 21 the machine and especially the tool support - as exemplified in Figure 3 a is drawn - is not negatively affected, because it should be within the base area of ​​the machine bed when viewed from above 1 lay.

[0088] It is precisely in this point that the design of the Figure 1 b of those of Figures 2 and 3a-c : The milling motor 12 is in the solution according to Figure 1b with its drive axle 12' arranged parallel to the Z-direction. The milling cutter gear 13 sits in a gear extension 14 of the cross slide 7, which in the direction of travel from the lower area of ​​the rear edge of the cross slide 7 in travel direction X' from the cutter axis 5' backwards towards the control cabinets 25 protrudes, whereby the gear extension 14 over the top edge of the Z-carriage 4 a,b, so that the milling motor 12 over the upper end of the adjacent Z-carriage 4 a or 4 b, in particular its portal 4 a 1 , extends across.

[0089] The milling motor 12is on the gear extension 14 to the rear, i.e. to the adjacent headstock or counter-headstock, here the counter-headstock 2', protruding and thus runs behind the Z-carriage 4 a at such a distance in the travel direction X' that the cross slide 7 any required transverse position relative to the Z-carriage 4 a can take.

[0090] The X-Motor 19 is preferably on the cross slide 7 opposite rear of the Z-carriage 4 a, with its drive axle 19' also parallel to the axis of rotation 10 runs.

[0091] To improve accessibility, the design of the Figure 2 as well as 3 a,c the gear extension 14, in which the milling cutter gear 13 is located, but protrudes diagonally upwards at the front on the top of the cross slide7 arranged. The milling motor 12 In this case, too, it sits with the same orientation of its drive axis on the back of this cutter extension 14, so that the milling motor 12 In this way it is positioned further forward towards the operator side and also somewhat lower.

[0092] The X-Motor 19 is in this case also on the back of the Z-carriage 4 a, namely at the back of the yoke 4 a 2 , attached, but with its drive axle 19' running in travel direction X'.

[0093] While in Figure 2 the gear extension 14, viewed in the Z-direction, has a rectangular contour, is in the Figures 3a , c this gear extension 14,again viewed in the Z-direction, with an approximately triangular contour, with the base of the triangle running in the travel direction X'. The shape and size of the gear extension 14 on the dimensions of the milling cutter gear to be accommodated 13 determines which is needed to cut the internal milling cutter 5 with the correct speed and torque from the milling motor 12 to drive from.

[0094] Regardless of the design, however, the following should apply - as Figure 3 a viewed in Z-direction, the axis of rotation 10 shown - that a milling cutter center 11" plumb line dropped in the X direction 30 a foot point 30 a of the plumb line, which in all operating states of the machine, viewed from above, is still in the space between the two Z-guides 6 a, b for the tool supports.

[0095] In order to achieve a high machining accuracy, the workpiece is usually additionally clamped in the Z direction as close as possible to the machining point by an additional clamping device 22 supported, as in Figure 2 as well as the Figures 1b in the machine and in the Figure 1c is represented as a single component in a specific design: The workpiece, usually a crankshaft 100, is clamped between two clamping parts, whereby two clamping plates are used as clamping parts 22 a, b are used, which are perpendicular to the axis of rotation 10 and are spaced apart from each other in the travel direction X', so that by moving their narrow sides against each other the workpiece can be clamped between them. For this purpose - see Figure 1c - in each of the clamping plates 22 a, b a prism-shaped image 22 a 1 , 22 b 1intended for installation on one side of the contour of the workpiece diameter to be clamped, the contact surfaces of which are provided with a sliding coating, since during machining the crankshaft 100 rotates and must be able to slide on the contact surfaces of the pressed-together mounts.

[0096] The two chipboards 22 a, b are on an additional carriage 23 which has a clamping Z-slide 23 a, which extends in the Z direction along the second Z-guides 16 a, b is controlled, and on which a clamping X-slide 23 b is moved in X-direction or in the travel direction X', which controls the two chipboards 22 a, b carries.

[0097] Both clamping plates 22 a, b are in X-direction or travel direction X' on the clamping X-slide 23 movable. LIST OF REFERENCE SYMBOLS

[0098] 1 Bed 1aMounting surface 1 bSupport surface 2 Headstock 2 'Counter-headstock 2 aWorkpiece spindle 3 a, bTool support 4 a, bGantry slide, Z-slide 4 a 1 , 4 b 1 side panel 4 a 2 , 4 b 2 yoke 4 'Front surface 5 Internal milling cutter 5 'Cutter axis 5 free passage 6 a, burst Z-guide 7 Cross slide 7 'Front surface 8 Bed angle 9 a, bTransverse guidance 10 Rotation axis, Z direction 11 Milling cutter axis 11 'Cutter center 12 Milling cutter motor 12' drive axle 13 Milling cutter gear 14 Gear extension 15 Spoke plate 15 free passage 15 bSpacers 15 cRotation ring 16 a, or side Z-guide 17aChip longitudinal conveyor 17 bChip cross conveyor 18 Milling cutter bearing 19 X-Motor 19 'Drive axle 20 transverse plane 21 Focus 22 Additional clamping device 22 a, bClamping part, clamping plate 22 a 1 / b 1 Recording 23 aClamping Z-slide 23 bClamping X-slide 24 chuck 25 control cabinet 26 Workspace cover 26 a, bStripes 27 flap 29 Support foot 30 Lot 30 aFoot point XExtension direction of the mounting surface X'Travel direction Ysecond transverse direction, perpendicular to the travel direction X'

Claims

1. Internal milling machine for machining workpieces that rotate during machining, having an internal milling cutter, with - at least one headstock (2) with a workpiece spindle (2a) rotatable in a controlled manner about an axis of rotation (10) running in the Z-direction, - a bed (1) with a mounting surface (1a) for the at least one headstock (2) extending in the Z- and X-directions and a lower support surface (1b), - wherein the mounting surface (1a) is inclined relative to the support surface (1b) by a bed angle (8) sloping downwards from the rear to the front, - at least one tool support (3a) with - a Z-slide (4a) movable in the Z-direction along the bed (1) on first Z-guides (6a, b), - a cross slide (7) movable along the Z-slide (4a) in one, preferably only one, direction of travel (X') transverse to the Z-direction along transverse guides (9a, b), - an annular internal milling cutter (5) which is rotatably mounted about the milling cutter axis (11) running in the Z-direction and driveable by a milling cutter drive, - a Z-passage open in the Z-direction being formed in the Z-slide (4a), characterised in that - the Z-slide (4a) is configured as a portal-shaped portal slide (4a) and is guided along the bed (1) by the two lower ends of its two free-ending legs on the first Z-guides (6a, b), - the direction of travel (X') of the cross slide (7) along the portal slide (4a) is inclined by an additional angle of no more than 45° relative to the X-direction.

2. Machine according to claim 1, characterised in that the additional angle is no more than 30°, preferably no more than 15°, preferably no more than 5°.

3. Machine according to any of the preceding claims, characterised in that - a second headstock, the counter-headstock (2'), is provided, that is moveable in the Z-direction along the bed (1) along second Z-guides (16a, b), and - in particular the second Z-guides (16a, b) are arranged inside the first Z-guides (6a, b).

4. Machine according to any of the preceding claims, characterised in that - the transverse guides (9a, b) are arranged opposite one another relative to the axis of rotation (10).

5. Machine according to any of claims 1 to 4, characterised in that - viewed in the Z-direction, with a plumb bob (30) dropped in the X-direction from the milling cutter centre (11'), at least during machining, preferably with the internal milling machine in no regular functional state whatsoever, the base point (30a) of this plumb bob (30) lies outside the space between the Z-guides (6a, b) for the tool support.

6. Machine according to any of the preceding claims, characterised in that - a second tool support (3b) is provided which is designed analogously to the tool support (3a) and is also moveable in the Z-direction and preferably along the same first Z-guides (6a, b) along the bed (1), and - in particular each of the two cross slides (7) is arranged in front of the respective front surface (4') of the portal slide (4a, b) carrying it and facing towards the respective other tool support (3a, b).

7. Machine according to any of the preceding claims, characterised in that the bed angle (8) is between 40° and 60°, in particular between 45° and 55°, in particular between 48° and 52°.

8. Machine according to any of the preceding claims, characterised in that - the milling cutter drive comprises a milling cutter motor (12) and a milling cutter gear (13) and the milling cutter gear (13) is arranged in a gear extension (14) which projects from the rest of the cross slide (7) in a transverse direction to the Z-direction, in particular the Y-direction perpendicular to the direction of travel (X'), and / or is not wider in the Z-direction than the rest of the cross slide (7), in particular the front plate (7a) of the cross slide (7) and - in particular the milling cutter motor (12), as viewed from above, is arranged in front of the milling cutter axis (11) and / or above the milling cutter axis (11).

9. Machine according to any of the preceding claims, characterised in that the transverse guides (9a, b) on the Z-slide (4a, b) are positioned and of a length such that the X-slide (7) can be moved forwards and downwards to such an extent that the axis of rotation (10) lies outside the free inner diameter of the internal milling cutter (5).

10. Machine according to any of the preceding claims, characterised in that - the internal milling cutter (5) is non-rotatably arranged in a passage (15a) of a spoke plate (15) extending in the transverse plane (20) to the Z-direction, and the spoke plate (15) has a plurality of spacers (15b) distributed over its circumference and extending in the Z-direction, with whose free ends it is non-rotatably fastened to a rotation ring (15c) which is mounted in the cross slide (7) by means of a milling cutter bearing (18) around the milling cutter axis (11) and / or - the internal milling cutter (5), in particular the spoke plate (15), is mounted relative to the cross slide (7) by means of a YRT bearing.

11. Machine according to any of the preceding claims, characterised in that - a longitudinal chip conveyor (17a), as viewed from above, is arranged in front of the front edge of the bed (1) and, in particular, from the end thereof a transverse chip conveyor (17b) runs along one of the end faces of the bed (1), and - in particular the longitudinal chip conveyor (17a) and / or the transverse chip conveyor (17b), as viewed from above, lies entirely within the maximum extension of the rest of the machine in the Z-direction and in the horizontal direction transverse thereto.

12. Machine according to any of the preceding claims, characterised in that the machine is designed and dimensioned so that the centre of gravity (21) of the entire machine including the bed (1) lies within the base area of the bed (1).

13. Machine according to any of the preceding claims, characterised in that - an additional clamping device (22) is provided which can be moved on an additional Z-slide (23a) in the Z-direction along the mounting surface (1a) of the bed (1) on guides, in particular the second Z-guides (16a, b), and / or - the additional clamping device (22) comprises two clamping parts (22a, b) movable relative to one another in the transverse plane (20), in particular clamping plates (22a, b) extending in the transverse plane (20) which project towards the axis of rotation (10) from an additional X-slide (23b) movable in the transverse direction on the additional Z-slide (23a), and - both of which are attached to the additional X-slide (23b) so as to be moveable in a direction transverse to the Z-direction, in particular the X-direction or the X' direction.

14. Machine according to any of the preceding claims, characterised in that the free inner passage (5a, 15a) of the internal milling cutter (5) and / or of the spoke plate (15) is larger than the outer diameter of the chuck (24) and in particular larger than the outer diameter of the workpiece spindle (2a).

15. Machine according to any of the preceding claims, characterised in that the X-motor (19) for driving the cross slide (7), as viewed from above, is arranged in front of the milling cutter axis (11) and preferably above the milling cutter axis (11), in particular on the upper side of the Z-slide (4a, b) or of the cross slide (7).