EP2611570A2

EP2611570A2 - Method and apparatus for centreless cylindrical grinding of a workpiece

Info

Publication number: EP2611570A2
Application number: EP11749189.4A
Authority: EP
Inventors: Erwin Junker; Hubert Müller
Original assignee: Erwin Junker Grinding Technology AS
Current assignee: Erwin Junker Grinding Technology AS
Priority date: 2010-09-01
Filing date: 2011-08-30
Publication date: 2013-07-10
Anticipated expiration: 2031-08-30
Also published as: KR20130106359A; DE102010036065B4; WO2012028604A2; US9242332B2; WO2012028604A3; US20130210322A1; JP5867876B2; JP2013536760A; BR112013004933A2; CN103118834A; CN103118834B; RU2013114312A; DE102010036065A1; ES2616583T3; EP2611570B1; KR101824552B1; RU2572649C2

Abstract

On a workpiece (1) there are first longitudinal portions (2a, 2b, 2c) which are rotationally symmetrical with respect to the continuous longitudinal axis (5) and are intended to be ground by way of centreless grinding. The workpiece (1) also has a second longitudinal portion (3), which is not rotationally symmetrical with respect to the longitudinal axis (5) and would lead to imbalance in the event of rotation. Therefore, a balancing weight (6) having a radially extending recess (7) is placed on the second longitudinal portion (3) (arrow 9, sliding ribs 8). The balancing weight (6) contributes largely to uniform distribution of the rotating masses, thus reduces the imbalance to a very low residual imbalance and allows reliable and precise centreless grinding.

Description

METHOD FOR ROUND-GRINDING A WORKPIECE, THE WORKPIECE-CONTAINING SYSTEM AND DEVICE FOR TIP-FREE CIRCULAR GRINDING

THE SYSTEM

The invention relates to a method for cylindrical grinding of a one-piece workpiece, the contour of which is defined by a continuous longitudinal axis and next to a first, to this longitudinal axis cylindrical longitudinal region also has a second longitudinal region in which the radial mass distribution with respect to the longitudinal axis is non-uniform.

Workpieces of this type are known. They are contoured according to the proviso of a continuous longitudinal axis, wherein this longitudinal axis is at the same time a central axis and an axis of rotation during later operation. However, they only partially have one or more lengths of cylindrical

Cross-section which are rotationally symmetric with respect to the longitudinal axis. In another length range, the radial mass distribution is non-uniform because the radial circumferential contour is eccentric or otherwise non-rotationally symmetric about the longitudinal axis. The best known example of such workpieces are the balance shafts in modern drive motors, in particular of motor vehicles. The increasing use of such balance shafts results from the conflicting demands for the quiet running of these engines as well as for low

Consumption data and lightweight construction in general. The use of balance shafts is not limited only to the drive motors of motor vehicles, but also exists in compressors and other technical fields.

In the operating jargon of the practitioners, such workpieces are referred to as "unbalanced." By this is meant that a work piece of this kind rotating on its own causes imbalance problems in that the rotational motion is nonuniform and is disturbed by vibrations or flapping motions With the increasing use of balance shafts and similar workpieces, the requirement arose to grind the mentioned workpieces with high precision, at least in their cylindrical and rotationally symmetrical length ranges, despite their unbalance behavior in an economical production process.

Various considerations have been made to meet this requirement with the known means of grinding technology. The knowledge of the applicant about this is based on their own operational practice, considerations of their own experiments as well as technical discussions, as they usually come about at symposia, exhibitions and similar events 5. A documentation or publication is not known.

Thus, it was thought to manufacture the aforementioned workpieces in their second length range specifically with a considerable oversize in such a way that an approximation to a rotational symmetry and thus a smooth concentricity would have been expected. After grinding, the excessive oversize would have been removed. Such a grinding process would not only be very complex and expensive, but would also bring a reduction in quality. Because after grinding, which represents a fine machining, a twisting or milling would lead to a distortion of the workpiece, so that the required dimensional and shape tolerances could not be met.

The idea of grinding these difficult workpieces by clamping them between tips had to be discarded. It was to be expected that due to their instability and workpiece geometry, the mentioned workpieces could only be sharpened between points with considerable effort. For example, an axial contact pressure, as it usually occurs when grinding between points, would have led to a deformation of the soft eccentric second length range.

Finally, the proven method for centerless cylindrical grinding came into question. Almost without exception, however, there are experiences with completely rotationally symmetrical workpieces. Therefore, it was known that a greater imbalance of the workpieces makes this Schiifprozess very difficult or even impracticable. Not only does an "unbalanced" workpiece rotate non-uniformly during centerless cylindrical grinding, which means that it does not produce a uniform rotational movement, which in itself means an inaccurate grinding result, and it even had to be taken into account that the uneven rotational movement even prevented the workpiece from being driven by the regulating wheel The conditions in the grinding gap are known to be so difficult that the regulating wheel can only transmit a sufficient torque to the workpiece if this is generally rotationally symmetrical with respect to the mass distribution Drive is not reliable from the outset, a centerless cylindrical grinding for these workpieces is out of the question.

The invention is therefore based on the object of specifying a method for cylindrical grinding, with which the cylindrical and rotationally symmetrical first length range of said "unbalanced" workpieces can be ground with great accuracy in a manner suitable for economical mass production.

The solution to this problem consists in the totality of the method steps according to claim 1 of the application. It is therefore first attached to the said workpiece a balancing mass and then ground the cylindrical first length range at least in a first length section according to the method of centerless cylindrical grinding.

The method according to the invention has the advantage that the usual and known machines can be used for centreless cylindrical grinding, cf. for example, e.g. Dubbel, Paperback for Mechanical Engineering, 18th edition, pages T89 / T90. The centerless cylindrical grinding is in the present case also advantageous because, for example, the said balancing shafts are produced in large quantities and even as a forged or cast blanks and after machining of very uniform nature. The unbalance of the individual balance shafts is thus in a relatively narrow frame. It can therefore be achieved with a single type of balance weight an economical procedure that allows a high degree of automation.

If the individual workpieces are more different from each other, it is also possible to measure their residual imbalance before grinding and to apply different balancing weights to the workpieces as needed. In this way, the quality of the grinding process can be further optimized. The leveling compounds are usually releasably attached to the workpieces. But they do not have to be removed immediately after completion of the cylindrical grinding, but can also be beneficial for further manufacturing operations. For example, a correspondingly sized and shaped balancing mass can also be used as a grip part for an automatic linking machine or an assembly process. Furthermore, the balancing mass may be useful for stabilizing the workpiece in further transport and machining operations.

It is understood that in mass production when using a single type of balancing mass complete compensation in the exact physical sense is not achieved in each case. However, it is sufficient for the interests of the practice, if the remaining imbalance is reduced to a very small value.

For a quick understanding of the application should be added that claim 1 requires the following definition. The first or second "length range" is the sum of the individual first and second length portions located on the workpiece For example, the balance shaft exemplified in Figures 1 and 2 of this application has three first length portions which may later serve as bearings The same applies to the second non-rotationally symmetrical length range.This definition is also evident from the dependent claims 2 and 3. It is therefore not always necessary to ground all the first length sections of the first length range. A development according to claim 4 is determined for the case that the balancing mass comes only for the process of grinding itself in question. In this case, the leveling compound is releasably secured and is removed again as soon as its first length range has been ground as far as necessary by centerless cylindrical grinding.

In many cases, it will be advantageous if the leveling compound is secured in the second length region of the workpiece. Then the cylindrical portions of the first length range are all free for cylindrical grinding.

A further advantageous embodiment relates to the case in which first and second longitudinal sections alternate on the workpiece and that a second longitudinal section is formed by a bridge section which extends between two first longitudinal sections and at a radial distance from the longitudinal axis of the workpiece. In this case, there is a possibility for attaching the balancing mass in a compensating body, which has a radially extending to its longitudinal axis recess. With this recess, the compensation body is placed on the bridge section and secured in the pushed position.

The backup of the balance weight may consist of a spring-loaded pressure bolt, but also be formed by one or more screw, also by resilient locking members, a device for clipping, a magnetic connection or a multi-part design of the balance weight, then laterally applied clamping rings, the items in patch Holding state together. If two and more rotationally symmetric first length sections are to be ground on the workpiece to be ground, the grinding can be carried out with a centerless cylindrical grinding machine which has a separate grinding set for each individual length segment, consisting of regulating wheel, grinding wheel and support ruler. In this way, all the first lengths can be ground simultaneously.

For the combination of a particular workpiece in question here with its associated leveling compound, there are various possibilities for joining the leveling compound in the form of a fitted compensating body with the workpiece at least for the duration of the grinding process. As this assembled assembly is then fed to the grinding machine, the workpiece and balancing unit is referred to as a system that is adapted to the nature of the workpiece and the particular grinding task. This system is an important assembly, running as a common unit at least through the grinding machine and in many cases can continue together. An advantageous feature of this system may be that the compensating body is releasably attached to the workpiece. Furthermore, it is an advantageous feature of the system when the workpiece and the compensating body are joined together by means of a radially extending recess in the compensating body, wherein the compensating body is placed by means of the recess on an eccentrically arranged longitudinal web of the workpiece. If the requirement for an automated operation exists, a separate device for cylindrical grinding of the system can be envisaged, as claimed in claim 11. This indicates that the system as a whole is machined in the centerless cylindrical grinding machine. A special adaptation in this case may be that there must be enough space for the rotation of the balance weight.

In simple cases and in small quantities, the balance weight will be applied to the workpiece individually and by hand. But if the conditions for mass production exist, it makes more sense if the assembly and optionally releasing the system is done automatically within the device or in close functional connection with the same. In this way, a combined treatment station can be envisaged, to which the workpieces located in Vorbearbeitungszustand be brought on a conveyor belt and spent by loading portals from the conveyor belt in an assembly station and from there back to the machine for centerless cylindrical grinding. Also the return transport of the finished ground workpieces to the conveyor belt is done by loading portals, possibly even a station for disassembly of the balance weights can be provided.

The invention will be explained in more detail in exemplary embodiments with reference to drawings. In the figures, the following is shown: Figure 1 shows two side views of a workpiece to be ground according to the proposal of the invention; while the workpiece is rotated in the lower side view relative to the upper side view by 90 ° about its longitudinal axis.

FIG. 2 is a representation corresponding to FIG. 1, wherein a balancing body forming the balancing mass is set onto a second longitudinal section.

FIG. 3 shows a partially sectioned view in the direction of the line AA of FIG. FIG. 4 is a schematic top view of a grinding machine, with which all rotationally symmetrical length regions of the workpiece are ground simultaneously.

FIG. 5 shows a side view belonging to FIG. 4.

FIG. 6 illustrates the principle of a combined processing station in which the method according to the invention can be advantageously carried out.

FIG. 1 shows in two views a balance shaft, as is increasingly used in modern internal combustion engines. This balance shaft is a good example of a workpiece 1, which can be advantageously ground by the method according to the invention. The workpiece 1 has a continuous longitudinal axis 5, after which the contour of the workpiece 1 is defined. Compared to the upper view of Figure 1, the lower view is rotated by 90 ° about the longitudinal axis 5. As can be seen from the comparison of the two views according to FIG. 1, the workpiece 1 has first length sections 2a, 2b, 2c, which are cylindrical relative to the continuous longitudinal axis 5 and can later serve as bearing points. Between the rotationally symmetrical first length sections 2 a and 2 b there is a second longitudinal section 3, which deviates in cross section from a rotationally symmetrical contour. In this case, the second longitudinal section 3 has an eccentric contour in the form of a flat longitudinal web, which here forms the bridge section and runs at a radial distance parallel to the longitudinal axis 5. A further longitudinal section 23, however, has a cross-section of the basic shape of a

Rectangles, which runs centrally to the longitudinal axis 5. The different lengths 2a, 2b, 2c and 3 and 23 are separated by cheeks 4, resulting in the first length sections 2a, 2b, 2c lateral abutment shoulders. According to the definition of this application, the first length sections 2a, 2b, 2c together form the rotationally symmetrical first length region of the workpiece, while the second longitudinal section 3 forms the second longitudinal region. In this, the radial mass distribution with respect to the longitudinal axis 5 is uneven, so that imbalance arises during rotation. The representation of Figure 2 corresponds to the illustration of Figure 1, but with the difference that on the second longitudinal section 3, a compensation body 6 is placed. As can be seen in connection with FIGS. 2 and 3, the compensating body 6 has the basic shape of a circular disk which is provided with a radially extending recess 7. The cross-sectional contour of the recess 7 has the basic shape of a rectangle, wherein on one side sliding ribs 8 are present. On the sliding ribs 8 opposite broad side of the recess 7 a pressure pin 1 1 is slidably mounted in a stepped bore 13, which is biased by a coil spring 12 in the direction of the interior of the recess 7. The compensating body 6 is placed with its recess 7 in the push-9 to the second longitudinal section 3, which is formed as a flat longitudinal ridge and has the basic shape of a rounded rectangle. The narrow side of the recess 7 forms a bearing 25 shoulder 10, against which the compensating body 6 abuts and is secured in this position by the pressure pin 11. It is readily apparent from FIGS. 2 and 3 that, starting from the longitudinal axis 5, the compensating body 6 is placed on the second longitudinal section 3 from the inside to the outside. During a rotation of the workpiece 1 about its continuous longitudinal axis 5, the compensation body 6 is thus additionally pressed by the centrifugal force to the second longitudinal section 3. The pressure pin 11 thus serves to secure the balance weight 6.

The workpiece 1, together with the compensating body 6, forms a common assembly or a system which as a whole has a balanced mass distribution in the radial direction. The system is thus radially balanced in the usual sense when it rotates about the continuous longitudinal axis 5. Referring to Figures 4 and 5, it is then illustrated how the system is ground in a centreless cylindrical grinding apparatus. Here, a separate grinding set is provided for each of the first length sections 2a, 2b, 2c, which consists in a known manner of a regulating wheel 15, a grinding wheel 16 and a support rivet 19. The said three parts together form a grinding gap, as shown in FIG. The regulating wheel 15, the grinding wheel 16 and the workpiece 1 rotate with the same direction of rotation. The longitudinal axis 5 of the workpiece 1 is doing to its axis of rotation and is located below a connecting line, which is pulled between the axes of rotation 17a, 18a of regulating wheel 15 and grinding wheel 16. The workpiece 1 is thus certainly pressed against the support ruler 19, i. pressed into the grinding gap. The groups of regulating wheels 15 and grinding wheels 16 are each located on a common control shaft 17 or grinding wheel shaft 18 and are held by appropriate spacers on the correct, the workpiece 1 adapted distance.

It should be noted that the figures of the embodiment are intended to illustrate only the principle of the invention. So, for example, the compensating body 6 does not necessarily have the shape of a circular disk; Also, a roller shape, an elliptical cross-sectional shape or another shape may be appropriate. In the figures, a centerless cylindrical grinding according to the principle of the vertical Einstechschleifens is shown mainly. However, the invention is not limited thereto. The other known methods for centerless cylindrical grinding may also be considered, such as longitudinal or continuous or oblique plunge grinding.

Likewise, the backup of the balance weight 6 shown in Figures 2 and 3 by a spring-loaded pressure pin 11 is only one of many possibilities. With the same success, one or more screw connections, resilient latching elements, a clip-on, a magnetic connection could also be used. training or a multi-part design of the balance weight 6 come into question, hold together the items in the deferred state at the laterally applied clamping rings.

The compensating body 6 can be placed by hand on the second longitudinal section 3a, in which case a fork-like pulling tool 14 (FIG. 3) for extracting the pressure pin 11 is sufficient. But it can also be thought to automate the process of assembling workpiece 1 and compensating body 6 and to install as a further function in the grinding device or a suitable additional station to this. In this case, a combined processing station may be advantageous, as shown schematically in FIG.

According to FIG. 6, the workpieces 1 are initially fed to a mounting station 21 on a conveyor belt 20 in the pre-machined state. There, in an automated process, each workpiece 1 is provided with its associated compensation body 6, that is, the said system is formed. This is then fed to the centerless cylindrical grinding machine 22, in which, according to FIGS. 4 and 5, one or more rotationally symmetrical length sections 2 a, 2 b, 2 c of the workpiece 1 are ground round. Subsequently, the system - consisting of the workpiece 1, which is now a finished part, and the balance weight 6 - returned to the conveyor belt 20 and the next processing or assembly stage. This conclusion of the grinding process is useful if the balance weight 6 is also advantageous for the further course of the production. It is also conceivable that anyway required further functional parts, which are required for the subsequent function of the workpiece 1, are already applied during grinding and are also designed as a balance weight accordingly Such functions are not in demand, the balance weight 6 also immediately after grinding again be removed from the workpiece 1. The assembly station 21 must then be supplemented by a dismantling station.

The invention has the advantage that the usual and existing machines for centerless cylindrical grinding can be used unchanged. Namely, if the balance weight 6 is properly sized and arranged, the workpiece 1 will rotate in the quiet concentricity in the machine, so that a good grinding result is readily achievable.

List of reference numbers

workpiece

2b, 2c first lengths

second lengths

Wangen

longitudinal axis

compensation body

recess

sliding ribs

push-on direction

contact shoulder

pushpin

coil spring

stepped bore

pulling tool

Regulating wheel

grinding wheel

Regelscheibenwelie

a rotation axis

Grinding wheel shaft

a rotation axis

edition ruler

conveyor belt

assembly station

Machine for centerless cylindrical grinding further length section

Claims

claims

1. A method for cylindrical grinding of a one-piece workpiece (1), the contour after

a continuous longitudinal axis (5) is defined and next to a first, to this longitudinal axis rotationally symmetrical length range has a second length range in which the radial mass distribution with respect to the longitudinal axis (5) is non-uniform, with the method steps that on the workpiece (1) a balancing mass is attached and then the first length range at least in a first length section (2a, 2b, 2c) by centerless cylindrical grinding

is ground, with this first length portion (2a, 2b, 2c) is in a by regulating wheel (15), grinding wheel (16) and support ruler (19) formed grinding gap.

2. The method according to claim 1, characterized in that the first length range of a plurality of first longitudinal portions (2a, 2b, 2c), which are separated from each other in the longitudinal direction of the workpiece (1).

3. The method according to claim 1 or 2, characterized in that also the second

Length range of several second lengths (3), which in

Longitudinal direction of the workpiece (1) are separated from each other.

4. The method according to at least one of claims 1 to 3, characterized in that the leveling compound to the workpiece (1) releasably secured and removed again, as soon as the first length range has been ground by centerless cylindrical grinding.

5. The method according to at least one of claims 1 to 4, characterized in that the balancing mass in the second longitudinal region of the workpiece (1) is attached.

6. The method according to at least one of claims 2 to 5, wherein a one-piece

Workpiece (1) is ground, in which first longitudinal sections (2a, 2b, 2c) and second longitudinal sections (3) alternate with each other and at least a second

Length section (3) is formed by a bridge section extending between two first longitudinal sections (2a, 2b, 2c) and at a radial distance from the longitudinal axis (5) extends, characterized in that a compensating mass bildender

Balancing body (6) with a radially to the longitudinal axis (5) extending recess (7) placed on the bridge section and secured in the 5 patch position.

Method according to at least one of claims 2 to 6, characterized in that in the case of a workpiece (1) having two or more first length sections (2a, 2b, 2c) for each of these longitudinal sections a separate grinding set for centerless cylindrical grinding with regulating wheel (15), grinding wheel (16) and support ruler (19) is provided and all first lengths (2a, 2b, 2c) are ground simultaneously.

System of a one-piece workpiece (1) whose contour is defined by a continuous longitudinal axis (5) and adjacent to a first rotationally symmetrical

Length range also has a second length range in which the radial

Mass distribution with respect to the longitudinal axis (5) is uneven, and from a balancing mass, which has a uniform radial mass distribution of the total

Workpiece (1) causes, for carrying out the method according to claims 1 to 7, characterized in that at least one the balancing mass bildender

Balancing body (6) in the second longitudinal region of the workpiece (1) is mounted.

System according to claim 8, characterized in that the compensating body (6) is releasably attached to the workpiece (1).

10. System according to claim 9, characterized in that the second length region of the workpiece (1) consists of at least one longitudinal section (3) in the form of a bridge section which extends at a radial distance from the longitudinal axis (5), and in that the compensating body ( 6) has a radially extending recess (7), with which it is placed on the longitudinal web. 11. A device for centreless cylindrical grinding of the system after at least one of

Claims 8 to 10, wherein the workpiece (1) with at least a first

Length section (2a, 2b, 2c) of the first length range in a by the regulating wheel (15), the grinding wheel (16) and the support ruler (19) formed grinding gap of

Is located.

12. The apparatus of claim 11, wherein the assembly and optionally releasing the system is done automatically within the device or in direct functional connection with the same.