DE102020008106B4 - Method for making an oval bushing - Google Patents

Abstract

Method for producing an oval bushing (108), comprising the steps: - providing an annular bushing blank (100) with a round bushing body (102); and- mechanically forming the socket body (102) by means of a forming device (10) to produce an oval socket (108) with an oval socket body (102); wherein during the mechanical forming of the socket body (102), two outer contour contact bodies (30a, 30b) of the forming device (10) which are arranged on the outside of the socket body (102) and each have a sectionally rectilinear and sectionally arcuate contact contour are moved in opposite directions (y1, y2) over the outer contour of the socket body (102). Socket body (102) can be moved towards each other, so that the socket body (102) is reshaped by the outer contour contact bodies (30a, 30b) and into an oval basic shape with two opposite straight socket legs (110a, 110b) and two opposite curved sections (112a, 112b) is brought; characterized in that during the mechanical forming of the socket body (102), an elongated contact body (32) of the forming device (10) extends through the socket recess (104) enclosed by the socket body (102).

Description

The invention relates to a method for producing an oval socket, with the steps: providing an annular socket blank with a round socket body and mechanically forming the socket body by means of a forming device for producing an oval socket with an oval socket body, with two arranged on the outside of the socket body during mechanical shaping of the socket body and in each case an outer contour contact body of the forming device, which has a sectionally rectilinear and sectionally arcuate contact contour, is moved towards one another in opposite directions over the outer contour of the socket body, so that the socket body is shaped by the outer contour contact bodies and brought into an oval basic shape with two opposite straight socket legs and two opposite curved sections becomes.

The invention further relates to a forming device for producing an oval socket, with a blank holder for receiving an annular socket blank with a round socket body and a plurality of contact bodies, by means of which the socket body can be formed to produce an oval socket with an oval socket body, the plurality of contact bodies each having two straight sections and sectionally arcuate contact contour comprising outer contour contact bodies, which are designed to be positioned on the outside of the socket body during mechanical shaping of the socket body and to be moved towards one another in opposite directions over the outer contour of the socket body, so that the socket body is reshaped by the outer contour contact bodies and into one oval basic shape with two opposing straight socket legs and two opposing curved sections.

In the publications US 4,930,331 A and JP 2017-113 769 A Methods for producing oval bushings are disclosed.

When manufacturing oval bushings, the challenge is maintaining tight manufacturing tolerances. In the prior art, oval bushings have so far been manufactured from pipe sections with an oval wall cross section. Here, a pipe segment with a circular wall cross-section is first formed to create an oval pipe shape. Ring segments are then separated from the oval tube and can be used as oval bushings. However, particularly high dimensional accuracy cannot be achieved with such an oval bushing production.

Another problem with this manufacturing process is the limited design options for the socket body of the oval socket. For example, by separating ring segments from an oval tube, it is not possible to produce an oval bushing that has a groove, a chamfer, a radius, a collar or a knurl. To date, complex post-processing has been required to create the corresponding socket properties.

The object on which the invention is based is therefore to enable the production of oval bushings with low manufacturing tolerances and complex bushing geometries.

The object is achieved by a method of the type mentioned at the outset, wherein during the mechanical forming of the socket body, an elongated contact body of the forming device extends through the socket recess enclosed by the socket body.

The invention makes use of the knowledge that significantly smaller manufacturing tolerances can be maintained if the ovalization is only carried out after a socket blank with a round socket body has been provided. This effectively avoids the introduction of dimensional deviations by separating bushing segments from an oval tube. Furthermore, the socket blank used can already have a comparatively complex geometry, which is maintained during the ovalization process.

The annular socket blank can be, for example, a pipe section. Alternatively or additionally, the annular bushing blank can also be produced or processed by machining, i.e. by cutting, before the ovalization process. The chip removal can be carried out, for example, by a turning process or on a lathe. The socket blank can therefore be a turned part. The machining pre-processing ensures high dimensional accuracy of the socket blank. Preferably, the oval bushing is produced first by machining and then by forming processing. The material selected must be suitable for both machining and forming. Alternatively, the socket blank can also be a cold-formed part, for example a bent part made of wire or sheet metal. Alternatively, the bushing blank can also have been produced using a casting or injection molding process and can therefore be a cast part or an injection molded part.

The annular socket blank can already have a groove, a chamfer, a radius and/or a knurl. The annular socket blank can also have a collar or be designed as a collar bushing blank. Corresponding geometries can be introduced into the socket blank with comparatively little manufacturing effort and are retained during mechanical forming to ovalize the socket body.

In a preferred embodiment of the method, during mechanical forming of the socket body, two inner contour contact bodies of the forming device arranged in a socket recess of the socket body enclosed by the socket body are moved outwards from one another in opposite directions over the inner contour of the socket body. Because the inner contour contact bodies are moved outwards over the inner contour of the socket body, the socket body is reshaped by the inner contour contact bodies and brought into an oval basic shape with two opposing straight socket legs and two opposite curved sections. Before forming with the inner contour contact bodies, the annular socket blank is preferably placed on the inner contour contact bodies. The socket blank can be placed in an automated manner, for example using an attachment device, or manually. The opposite socket legs preferably run essentially parallel to one another.

During the forming process, the inner contour contact bodies move apart, so that the distance between the inner contour contact bodies increases. The inner contour contact bodies can move at the same time or with a time delay. The inner contour contact bodies preferably carry out a mirror-symmetrical movement, with the travel length of the inner contour contact bodies preferably matching. A large part of the ovalization is created by moving the inner contour contact bodies. The amount of force required for ovalization changes as the inner contour contact bodies are moved. The amount of force required increases with increasing ovalization, i.e. the more the round socket body is brought into an oval shape. The moving apart of the inner contour contact bodies is preferably ended or interrupted when the pressure force of a working cylinder driving the inner contour contact bodies exceeds a threshold value. If the threshold value is exceeded, the forming is ended by moving the inner contour contact bodies apart. The inner contour contact bodies are moved via the working cylinder that drives the inner contour contact bodies. The threshold value can be the maximum force of the working cylinder. The working cylinder can be a pneumatic or hydraulic cylinder. As an alternative to the working cylinder, the inner contour contact bodies can also be moved by another drive, for example an electric motor drive.

The inner contour contact bodies each have an outer contour, which includes a curved contact surface and straight contact surfaces.

A method is also advantageous in which two leg contact bodies of the forming device, which are arranged on the outside of the socket body and each have a rectilinear contact contour, are moved in opposite directions during the mechanical forming of the socket body and are brought into contact with the rectilinear socket legs of the socket body. Here, the socket legs are pressed at least in sections by the leg contact bodies against rectilinear contact surfaces of the inner contour contact bodies. The remaining linear portion of the oval bushing is therefore generated by the leg contact bodies. This takes into account that the socket body will experience a springback after contact with the leg contact bodies is released. This springback is already taken into account during forming with the leg contact bodies and is therefore specifically compensated for. The leg contact bodies are moved by one or more drives. The one or more drives can be working cylinders. The working cylinders can be hydraulic or pneumatic cylinders. Alternatively, the drives can also be electric motor drives. The leg contact bodies preferably carry out a mirror-symmetrical movement. The leg contact bodies can be moved simultaneously or with a time delay.

The method is further advantageously further developed in that during the mechanical forming of the socket body, two arc contact bodies of the forming device, which are arranged on the outside of the socket body and each have an arcuate contact contour, are moved in opposite directions and brought into contact with the curved outer contour of the socket body. As a result, the curved sections of the socket body are pressed at least in sections by the curved contact bodies against curved contact surfaces of the inner contour contact bodies. By forming using the arc contact bodies, the springback of the socket body is compensated with high precision. In addition, this compensates for a kink in the curved section, which is caused by the pressing with the leg contact bodies. The arc contact bodies are moved by one or more drives. The drives can be a working cylinder. The working cylinders can be pneumatic or hydraulic cylinders. Alternatively, the drives can also be electric motor drives. The arc contact bodies can be used at the same time or with a time delay. The arc contact bodies preferably carry out mirror-symmetrical movements.

After the forming process has ended, the contact bodies are preferably moved back into their starting position so that the finished oval bushing can be ejected or removed. When the contact bodies are moved back, the oval bushing springs back by a defined amount. Since the springback of the oval bushing was already taken into account during the forming process, the bushing geometry corresponds to the intended target geometry after the springback has taken place. The springback of the socket body also creates a sufficient gap between the inner contour contact bodies and the oval socket so that the oval socket does not jam on the inner contour contact bodies when ejected. The ejection can take place, for example, by extending one or more ejection elements, for example ejector pins.

In a further embodiment of the method, during the mechanical forming of the socket body, two outer contour contact bodies of the forming device, which are arranged on the outside of the socket body and each have a sectionally rectilinear and sectionally arcuate contact contour, are moved towards one another in opposite directions across the outer contour of the socket body, so that the socket body is shaped by the outer contour contact bodies and is brought into an oval basic shape with two opposing straight socket legs and two opposing curved sections. The straight sections of the outer contour contact bodies form the socket legs of the socket body. The arcuate sections of the outer contour contact bodies form the curved sections of the socket body.

Before the socket body is mechanically shaped, the contact contour of at least one outer contour contact body arranged on the outside of the socket body is moved towards the outer contour of the socket body. By using outer contour contact bodies, no large forces have to be introduced into the socket blank via comparatively delicate inner contour contact bodies. This leads to a significantly lower tool load. Lower manufacturing tolerances are also achieved while minimizing production time. The forming process becomes more fail-safe and process times are shortened.

The outer contour contact bodies are moved by one or more drives. The one or more drives can be working cylinders, for example pneumatic or hydraulic cylinders. Alternatively, the drives of the outer contour contact bodies can also be electric motor drives. The outer contour contact bodies can be moved at the same time or with a time delay.

A method according to the invention is also advantageous in which the contact body serves as a contact surface for the inner contour of the socket body during the forming of the socket body and does not carry out any movement. A support surface is required in the interior of the socket blank to prevent the straight socket legs from bending excessively inwards during the forming process. The elongated contact body has a rectangular or square outer contour.

Furthermore, a method according to the invention is advantageous in which the reshaping of the socket body takes place in two reshaping steps using the outer contour contact bodies. In a first forming step, the movement of the outer contour contact bodies is interrupted before the respective end position of the outer contour contact bodies is reached. The first forming step is used to create the rough shape of the oval bushing. In a second forming step, the interruption of the movement of the outer contour contact bodies is resolved in order to move the outer contour contact bodies into their respective end positions. The second forming step is used for pressing and increases the dimensional accuracy when producing the oval bushing.

In another embodiment of the method according to the invention, in the first forming step, bushing legs that are inclined inwards and/or in the direction of the contact body are produced. In this case, the socket legs have a slight inward curvature. A corresponding socket leg shape is achieved by deflection beyond the target dimension during the forming process. Due to the deflection beyond the target dimension, the springback of the socket body is taken into account.

In another preferred embodiment of the method according to the invention, the outer contour of the socket body does not rest in sections on the contact contours of the outer contour contact body after the first forming step. Between the contact contours of the outer contour contact body and the outer contour of the socket body are located after the first Forming step air gaps in sections. In addition, the socket blank deviates laterally after the first forming step, so that there is still a dimensional inaccuracy in the front area of the socket body, which can be corrected by one or more further forming steps. Lateral deflection is fundamentally a disruptive but unavoidable mechanical effect when ovalizing bushing bodies. This effect is present as soon as ovalization begins. In the process described here, the socket blank only deviates slightly laterally after the first forming step, and this dimensional deviation can be corrected or further reduced in the further process.

In another advantageous embodiment of the method according to the invention, the contact body has two leg contact surfaces for the socket legs of the socket body, the distance between the leg contact surfaces being smaller than the target distance between the inner leg surfaces of the socket body. Consequently, the system body is undersized. By means of a corresponding travel allowance for the outer contour contact bodies, the deflection of the socket legs beyond the target dimension can be achieved. After the first forming step, there are also air gaps in sections between the surface of the contact body and the inner contour of the socket body.

In a further development of the method according to the invention, during mechanical forming of the socket body, an end face contact body of the forming device is moved in the axial direction of the socket body and brought into contact with the front outer contour of the socket body. As a result, the socket body is reshaped by the end face contact body. The end face contact body can be kinematically coupled to the elongated contact body, for example in such a way that the end face contact body is moved via a movement of the elongated contact body. Due to the deformation of the socket body caused by the end face contact body, a frontal dimensional deviation of the socket body is corrected or at least reduced.

In another preferred embodiment of the method according to the invention, the second forming step of forming the socket body by means of the outer contour contact body takes place during or after forming the socket body by means of the end face contact body. The socket body lies fully against the contact contour of the outer contour contact body due to the reshaping step of reshaping the socket body by means of the outer contour contact body and due to the deformation caused by the end face contact body. This takes into account that the socket body springs back by a process-dependent amount when the end face contact body is moved back and the outer contour contact body is moved back.

In another preferred embodiment of the method according to the invention, the socket blank is inserted into the forming device, the elongated contact body being moved in the longitudinal direction through the socket recess after the socket blank has been inserted into the forming device and before the socket body is mechanically formed.

The system body can be moved via a drive. The drive can be a working cylinder. The working cylinder can be a pneumatic or hydraulic cylinder. Furthermore, the drive of the system body can be an electric motor drive.

As part of the method according to the invention, the bushing blank can also be automatically inserted into the forming device and/or the oval bushing produced can be automatically ejected from the forming device. After the forming process, the outer contour contact bodies preferably move back to their starting position. The finished oval bushing is then preferably ejected automatically. For this purpose, the end face contact body is preferably retracted together with the contact body. This creates a gap between the outer contour contact bodies and the end face contact body, through which the finished oval bushing can fall downwards out of the forming device.

The object on which the invention is based is further achieved by a forming device of the type mentioned at the outset, the forming device according to the invention having an elongated contact body which is designed to extend through the socket recess enclosed by the socket body during the mechanical forming of the socket body.

The forming device is preferably set up to carry out individual or all steps of the method for producing an oval bushing according to one of the embodiments described above. With regard to the advantages and modifications of the forming device according to the invention, reference is first made to the advantages and modifications of the method according to the invention.

In a preferred embodiment of the forming device, the plurality of contact bodies comprise two inner contour contact bodies, which are designed for mechanical forming of the socket body to be positioned in a socket recess of the socket body enclosed by the socket body and to be moved outwards away from one another in opposite directions over the inner contour of the socket body, so that the socket body is reshaped by the inner contour contact bodies and into an oval basic shape with two opposite rectilinear socket legs and two opposing curved sections.

The forming device is further advantageously developed in that the plurality of contact bodies have two leg contact bodies each having a rectilinear contact contour. The leg contact bodies are preferably designed to be positioned on the outside of the socket body during mechanical forming of the socket body and to be moved in opposite directions and brought into contact with the rectilinear socket legs of the socket body, so that the socket legs are pressed at least in sections by the leg contact bodies against rectilinear contact surfaces of the inner contour contact bodies become. Alternatively or additionally, the plurality of contact bodies comprise two arc contact bodies each having an arc-shaped contact body. The curved contact bodies are preferably designed to be positioned on the outside of the socket body during mechanical forming of the socket body and to be moved in opposite directions and brought into contact with the curved outer contour of the socket body, so that the curved sections of the socket body are at least partially separated from the curved contact bodies against curved contact surfaces the inner contour contact body is pressed.

According to the invention, the plurality of contact bodies comprise two outer contour contact bodies each having an outer contour contact body which is rectilinear in sections and curved in sections. The outer contour contact bodies are designed to be arranged on the outside of the socket body during mechanical shaping of the socket body and to be moved towards one another in opposite directions over the outer contour of the socket body, so that the socket body is shaped by the outer contour contact bodies and into an oval basic shape with opposite rectilinear socket legs and two opposing curved sections. Alternatively or additionally, the plurality of contact bodies comprise an end face contact body, wherein the end face contact body is preferably designed to be moved in the axial direction of the socket body during mechanical shaping of the socket body and brought into contact with the front outer contour of the socket body, so that the socket body is reshaped by the end face contact body.

In another preferred embodiment of the forming device according to the invention, the elongated contact body is designed to serve as a contact surface for the inner contour of the socket body during the forming of the socket body and not to carry out any movement. The elongated contact body preferably has a rectangular or square outer contour.

In a further embodiment, the forming device according to the invention has one or more drives which are set up to move the plurality of contact bodies. The one or more drives can be working cylinders. The working cylinders can be pneumatic or hydraulic cylinders. Alternatively or additionally, the drives can include one or more electric motor drives. The forming device according to the invention preferably also has a control device which is connected in a signal-conducting manner to the one or more drives. Furthermore, the control device is set up to control the one or more drives for carrying out the method for producing an oval bushing according to one of the embodiments described above.

• 1 ein Ausführungsbeispiel der Umformvorrichtung samt Buchsenrohling in einer perspektivischen Darstellung;
• 2 die in der 1 abgebildete Umformvorrichtung vor dem Verfahren der Innenkonturkontaktkörper in einer Draufsicht;
• 3 die in der 1 abgebildete Umformvorrichtung nach dem Verfahren der Innenkonturkontaktkörper in einer Draufsicht;
• 4 die in der 1 abgebildete Umformvorrichtung nach dem Verfahren der Schenkelkontaktkörper und der Bogenkontaktkörper in einer Draufsicht;
• 5 ein Ausführungsbeispiel der erfindungsgemäßen Umformvorrichtung während des Einsetzens eines Buchsenrohlings in einer perspektivischen Darstellung;
• 6 die in der 5 abgebildete Umformvorrichtung nach dem Einsetzen des Buchsenrohlings, nach dem Bewegen des Anlagekörpers durch die Buchsenausnehmung und nach dem Heranfahren der Außenkonturkontaktkörper an den Buchsenrohling in einer perspektivischen Darstellung;
• 7 die in der 5 abgebildete Umformvorrichtung nach dem ersten Umformschritt des Umformens mittels der Außenkonturkontaktkörper in einer perspektivischen Darstellung;
• 8 ein Vergleich der nach dem ersten Umformschritt des Umformens mittels der Außenkonturkontaktkörper vorliegenden Buchsengeometrie mit der Soll-Geometrie;
• 9 die in der 5 abgebildete Umformvorrichtung nach dem Umformen mittels des Stirnflächenkontaktkörpers und nach dem zweiten Umformschritt des Umformens mittels der Außenkonturkontaktkörper in einer perspektivischen Darstellung;
• 10 ein Vergleich der nach dem Umformen mittels des Stirnflächenkontaktkörpers und nach dem zweiten Umformschritt des Umformens mittels der Außenkonturkontaktkörper vorliegenden Buchsengeometrie mit der Soll-Geometrie;
• 11 die in der 5 abgebildete Umformvorrichtung während des Auswerfens der hergestellten Ovalbuchse in einer perspektivischen Darstellung; und
• 12 ein Vergleich der finalen Buchsengeometrie mit der Soll-Geometrie.

Preferred embodiments of the invention are explained and described in more detail below with reference to the accompanying drawings. Show:

• 1 an exemplary embodiment of the forming device including the socket blank in a perspective view;
• 2 the ones in the 1 Pictured forming device before moving the inner contour contact body in a top view;
• 3 the ones in the 1 Illustrated forming device according to the process of the inner contour contact body in a top view;
• 4 the ones in the 1 Illustrated forming device according to the method of the leg contact bodies and the arch contact bodies in a top view;
• 5 an exemplary embodiment of the forming device according to the invention during the insertion of a socket blank in a perspective view;
• 6 the ones in the 5 shown forming device after inserting the socket blank, after moving the contact body through the socket recess and after Moving the outer contour contact body towards the socket blank in a perspective view;
• 7 the ones in the 5 Illustrated forming device after the first forming step of forming by means of the outer contour contact body in a perspective view;
• 8th a comparison of the socket geometry present after the first forming step of forming using the outer contour contact bodies with the target geometry;
• 9 the ones in the 5 Illustrated forming device after forming by means of the end face contact body and after the second forming step of forming by means of the outer contour contact body in a perspective view;
• 10 a comparison of the socket geometry present after forming using the end face contact body and after the second forming step of forming using the outer contour contact body with the target geometry;
• 11 the ones in the 5 Illustrated forming device during the ejection of the oval bushing produced in a perspective view; and
• 12 a comparison of the final bushing geometry with the target geometry.

The 1 shows a forming device 10 with which an oval bushing 108 can be produced.

To produce the oval bushing 108, an annular bushing blank 100 with a round bushing body 102 is first provided and inserted into a forming area of the forming device 10. In the forming area there are two movable inner contour contact bodies 12a, 12b. The inner contour contact bodies 12a, 12b extend through the socket recess 104 of the socket blank 100 inserted into the forming device 10. The socket body 102 of the socket blank 100 therefore runs around the inner contour contact bodies 12a, 12b.

The forming device 10 also has two opposite leg contact bodies 20a, 20b and two opposite arch contact bodies 24a, 24b. The leg contact bodies 20a, 20b and the arc contact bodies 24a, 24b are arranged on the outside of the socket blank 100 and can be moved in the direction of the socket blank, i.e. inwards. The leg contact bodies 20a, 20b each have a straight contact contour 22a, 22b. The arc contact bodies 24a, 24b each have an arcuate contact contour 26a, 26b.

The annular socket blank 100 can be, for example, a pipe section. Alternatively or additionally, the annular bushing blank 100 may have been machined or machined before being inserted into the forming device. For example, the socket blank 100 was processed or manufactured as part of a turning and/or milling process. The socket blank 100 shown has a front collar, with radii being present on the front material edges. The contact contours 22a, 22b of the leg contact bodies 20a, 20b and the contact contours 26a, 26b of the arch contact bodies 24a, 24b are adapted to the outer contour to be created and can, for example, have a material step.

The 2 shows that the inner contour contact body 12a has two rectilinear contact surfaces 14a, 14b and an arcuate contact surface 18a connecting the rectilinear contact surfaces 14a, 14b with one another. The inner contour contact body 12b has straight contact surfaces 16a, 16b and an arcuate contact surface 18b connecting the straight contact surfaces 16a, 16b to one another.

Based on that in the 2 In the state shown, the socket body 102 is mechanically reshaped by means of the inner contour contact bodies 12a, 12b.

For this purpose, the inner contour contact bodies 12a, 12b are inserted into the 3 shown opposite directions x ₁ , x ₂ moved apart over the inner contour of the socket body 102, so that the socket body 102 is reshaped by the inner contour contact bodies 12a, 12b. The socket body 102 is brought into an oval basic shape by the inner contour contact bodies 12a, 12b with two opposite straight socket legs 110a, 110b and two opposite curved sections 112a, 112b. The socket legs 110a, 110b produced run essentially parallel to one another. A large part of the ovalization is produced by moving the inner contour contact bodies 12a, 12b. The inner contour contact bodies 12a, 12b are moved via a drive, the drive having a pneumatic cylinder. A pneumatic cylinder is assigned to the inner contour contact body 12a. Another pneumatic cylinder is assigned to the inner contour contact body 12b. The drive for the inner contour contact bodies 12a, 12b is connected to a control device which controls the operation of the drive.

After the inner contour contact bodies 12a, 12b have been moved outwards to produce a first oval bushing 108, another one takes place Forming the socket body 102 by means of the leg contact bodies 20a, 20b and the arc contact bodies 24a, 24b.

Like in the 4 shown, the leg contact bodies 20a, 20b are moved in opposite directions y ₁ , y ₂ for further mechanical shaping of the socket body 102, so that the rectilinear contact contours 22a, 22b of the leg contact bodies 20a, 20b come into contact with the rectilinear socket legs 110a, 110b of the socket body 102 and the socket legs 110a, 110c are pressed at least in sections by the leg contact bodies 20a, 20b against the rectilinear contact surfaces 14a, 14b, 16a, 16b of the inner contour contact bodies 12a, 12b. Furthermore, the arc contact bodies 24a, 24b are moved in opposite directions x ₃ , x ₄ , so that the arcuate contact contours 26a, 26b of the arc contact bodies 24a, 24b come into contact with the curved outer contour of the socket body 102 and at least the curved sections 112a, 112b of the socket body 102 are pressed in sections by the curved contact bodies 24a, 24b against the curved contact surfaces 18a, 18b of the inner contour contact bodies 12a, 12b.

The leg contact bodies 20a, 20b are coupled to a drive. The drive has two pneumatic cylinders. A pneumatic cylinder is assigned to the leg contact body 20a, with a pneumatic cylinder being assigned to the leg contact body 20b. The pneumatic cylinders are connected to the control device, the control device controlling the operation of the pneumatic cylinders.

The arc contact bodies 24a, 24b are moved by means of a drive. The drive has two pneumatic cylinders. A pneumatic cylinder is assigned to the arch contact body 24a, with another pneumatic cylinder being assigned to the arch contact body 24b. The pneumatic cylinders are connected to the control device, the control device controlling the operation of the pneumatic cylinders.

Following the in the 4 In the state shown, the inner contour contact bodies 12a, 12b, the leg contact bodies 20a, 20b and the arch contact bodies 24a, 24b are moved back into their starting position so that the finished oval bushing 108 can be ejected. When the contact bodies 12a, 12b, 20a, 20b, 24a, 24b are moved back to the starting position, the finished oval bushing 108 springs back by a defined amount. Since the springback of the socket body 102 was taken into account when designing the contact bodies 12a, 12b, 20a, 20b, 24a, 24b and their travel paths, the intended target geometry is created comparatively precisely when the forming device 10 is opened. The finished oval bushing 108 can be ejected, for example, via one or more ejection elements, for example via one or more ejector pins, which push the oval bushing 108 down from the inner contour contact bodies 12a, 12b.

The 5 until 12 show an alternative embodiment of the forming device 10 as well as the bushing geometries produced during bushing production in cross section.

The 5 shows that the forming device 10 has an insertion opening 28, via which an annular socket blank 100 with a round socket body 102 can be inserted into the forming device 10.

The forming device 10 has two outer contour contact bodies 30a, 30b. The outer contour contact bodies 30a, 30b each have a contact contour that is straight in sections and curved in sections.

As the 6 shows, the outer contour contact body 30a is first moved to the outer contour of the socket blank 100 after inserting the socket blank 100. For this purpose, the outer contour contact body 30a is moved in the direction of movement y ₁ . Furthermore, an elongated contact body 32 is moved in the longitudinal direction z ₁ through the socket recess 104 of the socket blank 100. The elongated contact body 32 extends during the subsequent mechanical shaping of the socket body 102 through the socket recess 104 enclosed by the socket body 102, the contact body 32 serving as a contact surface for the inner contour 106 of the socket body 102 during the shaping of the socket body 102 and does not carry out any movement. The elongated contact body 32 therefore stands still during the forming process. Support surfaces are required in the interior of the socket blank 100 in order to prevent the straight socket legs 110a, 110b from bending excessively inwards during the forming process. The elongated contact body 32 has a substantially square outer contour.

The reshaping of the socket body 102 by means of the outer contour contact bodies 30a, 30b takes place in two shaping steps, in which 7 the first forming step is shown. As part of the first forming step, the outer contour contact bodies 30a, 30b are moved towards one another in opposite directions y ₁ , y ₂ over the outer contour of the socket body 102, so that the socket body 102 is reshaped by the outer contour contact bodies 30a, 30b and into an oval basic shape with two opposite rectilinear socket legs 110a, 110b and two opposite curved sections 112a, 112b. In the first forming step, however, the movement of the outer contour contact surfaces 30a, 30b is interrupted before the respective end position of the outer contour contact bodies 30a, 30b is reached. The first forming step initially serves to produce the rough shape of the oval bushing 108. In the first forming step, bushing legs 110a, 110b which are inclined inwards and towards the contact body 32 are produced. After the first forming step, the outer contour of the socket body 102 does not rest in sections on the contact contours of the outer contour contact bodies 30a, 30b and the leg contact surfaces 34a, 34b of the elongated contact body 32.

As the 8th shows, the socket body 102 was bent beyond the target dimension in the first forming step, so that the target geometry 114 deviates from the geometry of the socket body 102. The deflection beyond the target dimension is made possible by the fact that the contact body 32 has two leg contact surfaces 34a, 34b for the socket legs 110a, 110b of the socket body 102, the distance between the leg contact surfaces 34a, 34b being smaller than the desired distance between the inner leg surfaces of the socket body 102. The contact body 32 is therefore undersized.

As also in the 8th shown, the first forming step also leads to a lateral or frontal leakage of the socket body 102. This lateral or frontal dimensional deviation must be corrected below.

Furthermore, it shows 8th that the socket body has a circumferential groove 116 and chamfers 118a-118d on the front socket edges.

The forming device 10 also has two end face contact bodies 36, 38, the end face contact body 36 being movable. The end face contact body 38 is immovable and serves as a counter contact for the socket body 102 when the end face contact body 36 is moved. Both end face contact bodies 36, 38 thus take part in the forming process.

The 9 shows that the end face contact body 36 is moved in the axial direction z ₂ of the socket body 102 during mechanical shaping of the socket body 102 and is brought into contact with the front outer contour of the socket body 102, so that the socket body 102 is reshaped by the end face contact body 36. The end face contact body can be a forming plate which is kinematically coupled to the elongated contact body 32. Due to the deformation of the socket body 102 caused by the end face contact body 36, the frontal dimensional deviation of the socket body 102 is corrected or at least reduced (cf. 10 ).

Simultaneously or with a time delay to the movement of the end face contact body, the second forming step of forming the socket body is carried out by means of the outer contour contact bodies 30a, 30b. In the second forming step, the interruption of the movement of the outer contour contact bodies 30a, 30b is resolved in order to move the outer contour contact bodies 30a, 30b into their respective end positions. In the second forming step, further pressing takes place, which further increases the dimensional accuracy.

The 10 shows that the actual contour of the socket body 102 has moved closer to the target geometry 114.

The 11 shows that the outer contour contact bodies 30a, 30b and the end face contact body 36 are moved back to their starting position after the forming process. By breaking the contact between the socket body 102 and the contact bodies 30a, 30b, 36, the socket body 102 springs back, which has already been taken into account by the geometry of the contact bodies 30a, 30b, 36 and their travel paths.

The 12 shows that the geometry of the socket body 102 after springback essentially corresponds to the target geometry 114.

The outer contour contact bodies 30a, 30b and the end face contact body are each connected to a pneumatic cylinder, the operation of the pneumatic cylinder being controlled via a control device.

Reference symbols

10

Forming device

12a, 12b

Inner contour contact body

14a, 14b

straight contact surfaces

16a, 16b

straight contact surfaces

18a, 18b

arcuate contact surfaces

20a, 20b

Leg contact body

22a, 22b

straight contact contour

24a, 24b

Arc contact body

26a, 26b

arc-shaped contact contour

28

Insertion opening

30a, 30b

Outer contour contact body

32

investment body

34a, 34b

Leg contact surfaces

36

End surface contact body

38

End surface contact body

100

Socket blank

102

Socket body

104

Bushing recess

106

Inner contour

108

Oval bushing

110a, 110b

socket leg

112a, 112b

curved sections

114

Target geometry

116

Nut

118a-118d

Chamfers

x1, x2

Directions

x3, x4

Directions

y1, y2

Directions

z1

Longitudinal direction

z2

Axial direction

Claims (13)

Method for producing an oval bushing (108), comprising the steps: - providing an annular bushing blank (100) with a round bushing body (102); and - mechanically forming the socket body (102) by means of a forming device (10) to produce an oval socket (108) with an oval socket body (102); wherein during the mechanical forming of the socket body (102), two outer contour contact bodies (30a, 30b) of the forming device (10) which are arranged on the outside of the socket body (102) and each have a sectionally rectilinear and sectionally arcuate contact contour are moved in opposite directions (y ₁ , y ₂ ) via the Outer contour of the socket body (102) can be moved towards each other, so that the socket body (102) is reshaped by the outer contour contact bodies (30a, 30b) and into an oval basic shape with two opposite straight socket legs (110a, 110b) and two opposite curved sections (112a, 112b) is brought; characterized in that during the mechanical forming of the socket body (102), an elongated contact body (32) of the forming device (10) extends through the socket recess (104) enclosed by the socket body (102). Procedure according to Claim 1 , characterized in that the contact body (32) serves as a contact surface for the inner contour (106) of the socket body (102) during the forming of the socket body (102) and does not carry out any movement. Procedure according to Claim 1 or 2 , characterized in that the reshaping of the socket body (102) by means of the outer contour contact bodies (30a, 30b) takes place in two reshaping steps, wherein - in a first reshaping step, the movement of the outer contour contact bodies (30a, 30b) before reaching the respective end position of the outer contour contact bodies (30a , 30b) is interrupted; and - in a second forming step, the interruption of the movement of the outer contour contact bodies (30a, 30b) is resolved in order to move the outer contour contact bodies (30a, 30b) into their respective end positions. Procedure according to Claim 3 , characterized in that in the first forming step, bushing legs (110a, 110b) which are inclined inwards and/or in the direction of the contact body (32) are produced. Procedure according to Claim 3 or 4 , characterized in that after the first forming step, the outer contour of the socket body (102) in sections does not rest on the contact contours of the outer contour contact bodies (30a, 30b). Method according to one of the preceding claims, characterized in that the contact body (32) has two leg contact surfaces (34a, 34b) for the socket legs (110a, 110b) of the socket body (102), the distance between the leg contact surfaces (34a, 34b) being smaller as the target distance between the inner leg surfaces of the socket body (102). Method according to one of the preceding claims, characterized in that during mechanical forming of the socket body (102), an end face contact body (36) of the forming device (10) moves in the axial direction (z ₂ ) of the socket body (102) and with the front outer contour of the socket body (102 ) is brought into contact so that the socket body (102) is deformed by the end face contact body (36). Procedure according to Claim 6 or 7 , characterized in that the second forming step of forming the socket body (102) by means of the outer contour contact body (30a, 30b) during or after forming the socket body (102) takes place by means of the end face contact body (36). Method according to one of the preceding claims, characterized by the step: - inserting the socket blank (100) into the forming device (10); wherein the elongated contact body (32) is moved in the longitudinal direction (z ₁ ) through the socket recess (104) after inserting the socket blank (100) into the forming device (10) and before the mechanical forming of the socket body (102). Forming device (10) for producing an oval bushing (108), in particular by means of a method according to one of the preceding claims, with - a blank holder for receiving an annular bushing blank (100) with a round bushing body (102); and - a plurality of contact bodies, by means of which the socket body (102) can be formed to produce an oval socket (108) with an oval socket body (102); wherein the plurality of contact bodies comprise two outer contour contact bodies (30a, 30b) each having a sectionally rectilinear and sectionally arcuate contact contour, which are designed to be positioned on the outside of the socket body (102) during mechanical shaping of the socket body (102) and in opposite directions (y ₁ , y ₂ ) to be moved towards one another over the outer contour of the socket body (102), so that the socket body (102) is reshaped by the outer contour contact bodies (30a, 30b) and into an oval basic shape with two opposing straight socket legs (110a, 110b). and two opposing curved sections (112a, 112b); characterized by an elongated contact body (32), which is designed to extend through the socket recess (104) enclosed by the socket body (102) during the mechanical forming of the socket body (102). Forming device (10). Claim 10 , characterized in that the plurality of contact bodies - comprise an end face contact body (36), wherein - the end face contact body (36) is preferably designed to be moved in the axial direction (z ₂ ) of the socket body (102) during mechanical forming of the socket body (102) and with the front outer contour of the socket body (102) to be brought into contact, so that the socket body (102) is reshaped by the end face contact body (36). Forming device (10). Claim 10 or 11 , characterized in that the elongated contact body (32) is designed to serve as a contact surface for the inner contour (106) of the socket body (102) during the forming of the socket body (102) and not to carry out any movement. Forming device (10) according to one of the Claims 10 until 12 , characterized by : - one or more drives which are set up to move the several contact bodies; and - a control device which is connected to the one or more drives in a signal-conducting manner and is set up to control the one or more drives for carrying out the method according to one of the Claims 1 until 9 head for.

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