KR20080022114A - A method for mechanical machining, in particular for drilling and turning light alloy wheels, and a mechanical machining installation operating according to this method - Google Patents

Abstract

A method for mechanical machining, in particular for drilling and turning wheels (1) of light alloy, comprising a step (30) of centring and locking the wheel to be machined prior to the steps (40, 50) of drilling and turning the wheel. In the centring step (30) provision is made for the further steps of arranging a seating device for the wheel (1) comprising a plurality of elements having the form of a circular sector (4) in plan view, coplanar with each other and spaced apart from each other angularly, each of the sectors (4) being movable along a predefined radial direction (R), the directions (R) intersecting at a common central axis (Z) running perpendicularly to the radial directions, each of the sectors (4) having a respective seating surface (4a) for a corresponding part of the outer front portion (2) of the wheel (1) arranged in a position facing the sectors (4), and of moving the plurality of seating sectors (4) along the respective radial directions (R) to suit the outside diameter of the wheel undergoing the step of centring, so that the seating of wheels (1) having different diameters varying within a preselected range of values is obtained on the device. An installation operating according to the above-mentioned method is also described. ® KIPO & WIPO 2008

Description

A method for mechanical machining, in particular for drilling and turning light alloy wheels, and a mechanical machining installation operating according to this method}

The present invention relates to a method for mechanical machining, and more particularly to a method for drilling and turning light alloy wheels, according to the preamble of the independent claim. The subject matter of the present invention also relates to a machining facility operating according to the above-mentioned method.

The invention is not exclusive, but belongs to a particular technical field of machining operations provided for the production of vehicle wheels of light alloys, in particular aluminum alloys. It is to be understood that the present invention can likewise be applied to the mechanical processing of other types of mechanical parts, characterized by substantially axially symmetrical geometries (eg wheels, brake discs, etc.).

In this particular field, castings of semi-finished wheels undergo a cycle of machining by removal of chips, primarily by drilling and turning. The part is first properly centered and clamped to a suitable workpiece fixture.

Typically, the industrial sector of mechanical processing for the production of light alloy wheels is characterized by high yields with fairly short cycles of time for processing each individual wheel, which requires high productivity. Applicable to mass production.

Moreover, in today's world, taking into account the development and globalization of the market, it is possible to respond promptly and effectively to the requirements and demands imposed in the market, especially with regard to changes in production and changes in the characteristics of the sector, and to recover machining and tooling And devices that are capable of optimizing the cost and at the same time recognizing each individual part supplied to the manufacturing line and applying the most appropriate working cycle to it, the parts (wheels) having a (dimensional, type, geometric Substantial manufacturing flexibility is required to include a manufacturing line that can be supplied to machining centers in an almost random sequence.

Another requirement that coincides with this response speed and flexibility imposed by the market is the ability to change production cycles economically, quickly and effectively, which means using skilled labor to intervene at that level in the production line. Even in more difficult cases.

In addition to this, there is now another request to obtain a higher level of accuracy of dimensions and shapes in the manufacture of light alloy wheels for the purpose of reducing, if not possible, the need for subsequent corrective action to balance the wheels. All of this leads to a dramatic reduction in the use of materials traditionally used in balancing operations, such as lead, which is both well known to be toxic and difficult to incidentally dispose of.

The main object of the present invention is therefore to make available a method and apparatus for machining which are designed to meet the above mentioned requirements, in particular for drilling and turning light alloy wheels.

The above and other objects, which will become apparent from the following description, are achieved according to the invention by a method and a plant for mechanical processing carried out in accordance with the appended claims.

Features and advantages of the present invention will become apparent from the following detailed description of the preferred examples of the embodiments described as non-limiting examples with reference to the accompanying drawings.

1 is a block diagram of the main steps in a machining method according to the invention.

2 is a schematic view of the axial part of the wheel in the machining step of the method according to the invention.

FIG. 2A is an enlarged view of the detailed view of FIG. 2 indicated by arrow A. FIG.

3 is a schematic plan view from the top of the seating and centering device in FIG. 2;

4 and 5 are schematic views of the axial cross section of the wheel in the machining step of FIGS. 2 and 3;

6 is a partial cross-sectional view of an enlarged portion of a wheel at another stage of the machining method described herein.

FIG. 7 is a schematic diagram of a plant for mechanical machining action according to the steps of FIG.

Referring first to FIG. 1, the block diagram depicted represents a sequence of major steps in the method for mechanical machining, in particular drilling and turning, of light alloy wheels performed according to the invention.

In the description of the invention, reference will be made to the mechanical processing of semi-finished wheels, generally designated by reference numeral 1 and schematically shown in the drawings, which are obtained by a casting process, supplied on a line, where the main machining operations of drilling, turning and surface finishing, which are the subject of the method proposed by the present invention, are carried out.

In a first step of the method of the invention, denoted by reference numeral 10, preparation is made to undergo a recognition process for the wheel 1, in which the detection means (e.g. a vision means having a television camera or the like) is provided. Through use, or using a sense means, some key properties for the geometry of the wheel, for example height and / or meaningful diameters, are recognized and additionally or alternatively obtained in the casting process. Some parameters for a given geometric shape or style are recognized. Once these features are detected, they are compared with the parameters stored in the appropriate databank by the processing unit, in which the corresponding machining and tooling of each individual detailed type of wheel is concerned. Information on the number and cycles is pre-populated. The automatic recognition step results in a batch or single portions of semi-machined wheels being able to be fed to the machining line in a substantially random sequence, which, once all the information has been received, Machining centers can be automatically provided to machine certain types of wheels if properly recognized. This makes the machining line particularly flexible, achieving high overall productivity.

In a second step of the method indicated by reference numeral 20, preparation is made for the first initial orientation of the wheel 1 for subsequent formation of the valve hole, the position of the valve hole being correlated with the geometry of the wheel, In particular it is correlated with the shape of the front part 2 of the wheel extending radially from the central hub 3 (the position of the valve hole thus depends on the size and number of spokes extending radially from the hub). ).

In a subsequent step of the machining method, denoted by reference number 30, the wheel 1 undergoes a seating and centering action carried out by appropriate means, such that the centered wheel is produced in the subsequent machining step, in particular in the subsequent Can be locked during drilling.

In a preliminary seating step, preparations are made using a seating device comprising six elements, all in the form of rounded flat parts on the top view, all indicated by the reference numeral 4, which are coplanar with each other and at regular regular angles in pitch. spaced apart by (pitch). The sectoral portions are guided on individual slides 5 along the radial direction indicated by R, which intersect at a common central axis Z extending perpendicular to the radial direction R. Each sector 4 has a surface 4a which can be in seating contact with corresponding parts of the surface of the front part 2 of the wheel, which is arranged in a position facing the sector 4. Since the wheels are surface contacted on the scalloped portion 4, seating is obtained at the surface portions that are substantially annularly developed. Since the seated surface is a rough cast surface and in particular subject to distortion due to the heat treatment previously carried out, the seating on the annular surface of the fan part 4 allows this distortion to be averaged, so that for subsequent centering operations Determine the intermediate seating plane to be used as the basis. Because of the provision of the fan-shaped portions 4 which are guided to move along the respective radial direction R, it is possible to ensure proper surface seating for wheels with different diameters, which are varied to a predetermined range of values. For example, the seating fan portion 4 is guided, the operation being under numerical control. In general, wheels of different types and sizes can be accommodated on the same seating device without the need for using different tools, resulting in greater work flexibility.

In Fig. 3, the solid and dashed lines are used to represent two separate positioning arrangements of the fan portion 4 which provide the most appropriate seating for a pair of wheels with different diameters.

The three sectors 4 of the first group (for clarity, denoted by 4 'in FIG. 3) are sided with the wheel along the corresponding radial direction R to reach the position where the wheel is centered. It can be moved until there is directional contact, in particular until there is a lateral contact with the wheel edge 2a protruding circumferentially from the front part 2 of the wheel. The three remaining sectoral portions 4 provide only a seating function, for example, and in any case can reach radial positions which are distanced from the wheel edge 2a. After seating, centering the wheel may be performed as an alternative to that described above using different methods. For example, the centering means may use three elements of its own centering type or electronic detectors, which come into contact with the individual points of the wheel surface located proximate to the main geometric axis of the wheel indicated by X in the figure. Centering can be performed at the outer surface (diameter D1 in FIG. 4) or at the central portion or core 5 extending at the central hub 3 (diameter D2 in FIG. 4), Or on a rough hole 6 (diameter D3 in FIG. 6) intended to connect the wheel to the vehicle as obtained in the casting process. As an alternative, a centering diameter D4 can be formed on the surface ring 7, which surface ring is provided especially for the casting process and is intended to be subsequently removed by machining (FIG. 5). ).

The diameter D4 can be selected as a standard diameter for a range of wheels that differ in type or dimensions within a predetermined range of values, so the centering is substantially independent of the type and size being machined.

Reference numeral 4b denotes a locking braket, which is integral with the individual fan portion 4 and is installed to lock the portion once it has reached the center position. Once the centering has been performed and the wheel 1 has been locked in the centering position, the method provides a mechanical machining step 40 of drilling, in which holes 6 for securing the wheel to the vehicle are provided with the hub of the wheel ( 3) is obtained.

In this step, by milling three surfaces 8 (FIG. 6) located at the wheel diameter D1 close to the maximum outer diameter De of the wheel (and arranged at an angle of 120 ° from each other). It is advantageous for the machining to take place. In particular, each of the three surfaces 8 has a surface portion 8a intended for contacting the centering means and a surface portion 8a for seating the wheel in the work-holding device for subsequent machining operations. In addition, preparation can be made for localized machining of the front surface partition 8c as shown in FIG. 6. Since these surfaces 8 are machined at the same time as drilling holes for attaching the wheels to the vehicle, they are characterized by high dimensional accuracy which correlates with the accuracy of the centering obtained in step 30 described above. Moreover, because of the preliminary steps of mounting and centering described above, the surfaces 8a (and surfaces 8c, if provided) are parallel to the intermediate seating plane of the wheel, and using the surface in the step of turning is very accurate. Make sure you get a balance.

In another step 50 of the invention, a turning is carried out on the wheel 1, in particular a turning on the cylindrical wall 9 arranged to align the wheel with the tire.

In this step, the centering means comes into contact with the stationary contact surface 8 in order to ensure high centering accuracy and consequently a low imbalance of the wheel which can be detected.

It should be understood that the machining steps 40, 50, which are drilling and turning, respectively, may be arranged in the reverse order to that described above.

Referring to FIG. 7, reference numeral 100 only schematically schematically shows a plant for mechanical machining according to the method described herein as previously described.

The installation 100 comprises a line 101 for conveying and transporting the semi-finished wheel 1 extending between the inlet station 101a and the outlet station 101b.

Further along the station 101a, the installation includes a work site 102 arranged for recognition and orientation of the wheel according to steps 10 and 20 of the machining method.

Reference numeral 103 denotes a machining center for drilling, in which the wheel 1 undergoes a step 30 of centering and a step 40 of drilling. Further following from the drill machining center 103, a machining center 104 for turning is provided, in which the wheel 1 is transported so that the step 50 corresponding to the turning is carried out and the wheel at the end of the turning. Move to the discharge station 101b.

The present invention thus achieves the proposed object and provides the advantages presented in comparison with known solutions.

Independent of the size of the batch of parts to be fed and the type of wheels, due to the fact that semi-machined wheels can be supplied to the mechanical processing line in a random sequence, it can be obtained by the method according to the invention. There is a major advantage to noteworthy flexibility.

Another advantage is the accuracy of the centering obtained by the method described in the present invention, which results in significantly reducing the need for subsequent wheel balancing action, with only a particularly small degree of wheel imbalance in the wheel after the machining action. To lose.

Another advantage is that the methods and facilities described herein are designed so that they do not require intervention by skilled personnel to refurbish machining centers.

Another advantage is that, with machines equipped with automatic tool magazines, the method disclosed by the present invention enables working without interruption without stopping the facility except in the event of scheduled maintenance and failures.

The invention can be used in mechanical machining of parts such as wheels of automobiles.

Claims (16)

A method for mechanical machining, in particular for drilling and turning light alloy wheels 1, by centering the wheels that must undergo machining before the steps 40, 50 of drilling and turning the wheels and A locking step 30 and a locking step, the centering step comprising: Arranging a device for seating a wheel 1 comprising a plurality of elements in the form of a rounded sectoral part 4 coplanar with one another and angularly spaced from each other when viewed from above, wherein the sectoral part Each of (4) can move along a predetermined radial direction (R), the radial direction (R) intersects at a common central axis (Z) extending perpendicular to the radial directions (R), Each of the sectors 4 has a seat 1 having a separate seating surface 4a with respect to the corresponding part of the outer front part 2 of the wheel 1 arranged at a position facing the sector 4. Disposing a device for seating; By moving the plurality of seating sectors 4 along the respective radial direction R to fit the outer diameter of the wheel 1 undergoing the centering step, it has different diameters which are varied within a range of preselected values. Moving the seating fan portion, in which seating of the wheels (1) is obtained on the device. The method of claim 1, The round fan seating elements (4) are angularly spaced at regular pitches around the central axis (Z). The method according to claim 1 or 2, The round fan seating elements (4) are operated under numerical control to be guided along individual radial directions (R) on individual slides (5). The method of claim 1, wherein The plurality of elements comprises six seating elements (4) in the form of a round fan that move in synchronization along a separate radial direction (R). The method of claim 1, wherein A method of mechanical processing comprising moving at least a portion of the round fan elements (4) until the round fan seat elements (4) are in lateral contact with the wheels (1) to effect centering of the wheel. The method of claim 5, wherein A first group of three rounded sector seating elements 4 angularly spaced at regular pitches, and a seating sector portion 4 'angularly disposed at positions alternate with the sectors of the first group A second group of) is provided, wherein the fan-shaped portion 4 'of the second group protrudes circumferentially from the outer front surface portion 2 of the wheel so as to reach the centering position of the wheel. Mechanical processing method, which can move radially until it comes in contact with the lateral edge of the machine. The method of claim 1, wherein The surface of the front part (2) of the wheel made to rest on the sector (4) is a rough surface, obtained in the casting process of the wheel (1). The method of at least one of the foregoing, Prior to centering, a recognition step 10 of the semi-machined wheel 1 supplied to the machining center is provided, the recognition means for identifying the machining and tool work cycles and the number of times for the recognized wheel 1, Machining can be performed by detecting features of the geometry of the wheel 1, comparing these features with those stored in the databank, and by sending the necessary information for tooling and mechanical machining to the unit controlling the machining center. The semi-machined wheels 1 that have to undergo can be fed to the machining center in substantially random sequences, the features of each wheel 1 being recognized in the recognition step 10, and the machining center, And are automatically arranged and controlled with provided machining and tool operating cycles for each corresponding wheel. The method of claim 8, The characteristics of the wheel (1), which are meaningful in the step of recognizing the wheel, include the type of wheel, the diameter of the wheel, or the height for the shape of the wheel obtained from the finished product from the casting process. The method according to claim 8 or 9, After the recognition step (10), the step (20) of the wheel (1) is made to identify the position where the valve hole is formed in the wheel. The method of claim 10, The centering step 30 follows the orientation step 20, precedes the drilling step 14, and in which the holes 6 for securing the wheel 1 to the vehicle in the drilling step are obtained in the wheel hub. Processing method. The method of claim 11, In the step 30 of centering and locking the wheel arranged for the operation of the drilling, the surfaces 8 located at the wheel diameter close to the maximum outer diameter De of the wheel are also mechanically produced, even by milling. Processing method. The method of claim 12, The surfaces (8) are made on the outer diameter (D1) of the wheel on the front part (2) of the wheel extending radially from the central hub. The method according to claim 12 or 13, The surfaces 8 constitute mechanical points, which constitute contact points for the contact of the centering means capable of centering the part in the turning step 50 of the wheel 1 carried out after the drilling step 40. Way. Equipment for mechanical machining, in particular for drilling and turning the wheels (1) of light alloy, carried out by the machining method according to one or more of the preceding claims. Viewed from above, for seating and centering a light alloy wheel 1 undergoing mechanical processing, comprising a plurality of seating elements in the form of rounded sectoral portions 4 which are coplanar with each other and angularly spaced from one another. As a device, each of the sectors 4 can move along a predetermined radial direction R, the radial direction R being in a common axis Z extending perpendicular to the radial direction R. Each of the sectors 4 has a separate seating surface 4a against the corresponding part of the outer front part 2 of the wheel, which is arranged at a position facing the sector 4, The portion can move along an individual radial direction R to fit the outer diameter of the wheel 1 undergoing the centering step, so that the wheel 1 with different diameters varying within a range of preselected values. Arrangements are obtained on the device.

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