Manufacturing a brake drum

Abstract

The invention relates to a method for manufacturing a brake drum for a vehicle. In the method, at least two connecting elements (1), each having a mounting section (7) and formed at least partially from a first material, are provided (B). An intermediate brake drum component (30) with a shell element (26) is produced by centrifugal casting of a second material within a die device (20, 40) rotatable about an axis of rotation (25) (E). During centrifugal casting, the connecting elements (1) are arranged at a predetermined distance (d) from one another and extend at least partially in a radial direction (R) relative to the axis of rotation (25) into the formed shell element (26).

Description

[0001] The invention relates to a method for manufacturing a brake drum for a vehicle. In this method, at least two connecting elements, each having a mounting section and at least partially formed from a first material, are provided. The invention further relates to a brake drum for a vehicle. The invention further relates to a vehicle comprising a brake drum.

[0002] Brake drums for vehicles are a well-known design. They feature a friction surface that is essentially rotationally symmetrical to the vehicle's wheel axle and faces inwards. To brake the vehicle, brake shoes are pressed against the friction surface from the inside. Brake drums of this type are often manufactured using a monolithic casting process from a single material.

[0003] DE 10 2011 054 484 A1 describes a brake drum for a vehicle with a substantially cup-shaped base body made of a light metal. A friction element is attached to a radial inner surface of the base body. A frictional force acts on the friction element during braking. The friction element is bonded to the base body by friction welding.

[0004] EP 3 314 141 B1 describes a brake drum for a commercial vehicle, comprising a shell section. The shell section has a friction surface that is rotationally symmetrical about an axis of rotation. A connection area of ​​the brake drum has a mounting section. The shell section and the connection area are made of different materials and are connected to each other. The shell section and the connection area are manufactured separately, with the shell section having a first connection section and the connection area having a second connection section. The first and second connection sections are materially bonded to each other by welding.

[0005] Against this background, one object of the present invention is to create improved brake drums whose manufacture is both efficient and cost-effective.

[0006] This problem is solved according to the invention by a method of the type mentioned at the outset with the features of claim 1.

[0007] Accordingly, a method for manufacturing a brake drum for a vehicle is provided, in which an intermediate brake drum component with a shell element is produced by centrifugal casting of a second material within a die device rotatable about an axis of rotation. The connecting elements are arranged at a predetermined distance from one another during centrifugal casting. Furthermore, the connecting elements extend at least partially in a radial direction relative to the axis of rotation into the shell element formed during centrifugal casting.

[0008] The invention is based on the assumption of those skilled in the art that the composite casting of multi-part vehicle components is only profitable in the high-priced vehicle segment due to the increased demands on manufacturing process control. For example, brake discs are cast in a gravity sand casting process using expendable molds. At the time of the invention, those skilled in the art assumed that the mass advantage resulting from composite casting could not be efficiently and profitably implemented for small cars and vehicles in the lower price range, which often use drum brakes.

[0009] The solution according to the invention overcomes the aforementioned technical limitation by producing the composite casting of a brake drum using centrifugal casting, whereby connecting elements are arranged at a predetermined distance from each other and aligned radially to the axis of rotation during the centrifugal casting process. In this way, the intermediate brake drum component with a shell element can be manufactured using the particularly efficient centrifugal casting process. Simultaneously, thin-walled steel sheets can be used as connecting elements for the production of the brake drum.

[0010] The term connecting element is preferably to be understood as forming a part of the brake drum by means of which the brake drum can be mounted (so to speak, connected) to the vehicle.

[0011] Preferably, the intermediate brake drum component has more than two connecting elements. This allows the efficiency of the inventive method to be further scaled. A plurality of connecting elements can thus be arranged along the mold assembly with a predetermined distance between two adjacent connecting elements.

[0012] The term "composite casting" is preferably understood by those skilled in the art to mean a casting process in which the intermediate brake drum component is produced from different materials, namely the first and second materials. In the process according to the invention, the connecting element is preferably provided as a solidified workpiece and arranged in the die casting device. In other words, any casting and rolling process for producing the connecting element is carried out separately before the connecting element is provided according to the process according to the invention.

[0013] The term "brake drum intermediate product" is preferably to be understood as being designed for further processing into a brake drum blank and ultimately into a mountable brake drum. Centrifugal casting, with the simultaneous arrangement of at least two connecting elements within the mold, preferably creates a shell element that extends over the at least two connecting elements. In other words, the at least two connecting elements of the brake drum intermediate product are connected to each other via the shell element.

[0014] The formulation, according to which the connecting elements in centrifugal casting extend at least partially in a radial direction to the axis of rotation into the shell element formed in centrifugal casting, is preferably to be understood as meaning that the respective connecting element is arranged within the mold device in such a way that it projects into the mold cavity, where it is surrounded by the liquid cast iron and embedded during solidification.

[0015] The arrangement of the connecting elements at a predetermined distance from each other is preferably achieved by means of at least one retaining element.

[0016] When the brake drum is mounted in the vehicle, the mounting elements are preferably designed to rotate a wheel rotation axis. This wheel rotation axis preferably has the same orientation and position relative to the respective mounting element as the rotation axis around which the die assembly rotates during centrifugal casting.

[0017] The wording, according to which the connecting elements are at least partially radially oriented

[0018] The phrase "extend in a direction relative to the axis of rotation into the formed shell element" includes designs in which the connecting elements extend exclusively radially into the shell element. This formulation also includes designs in which the connecting elements, in addition to their radial extension, also extend partially axially into the shell element.

[0019] According to a preferred embodiment of the method according to the invention, the connecting elements are each manufactured as a stamped steel sheet or as a formed steel pot. This allows connecting elements to be provided particularly easily and efficiently.

[0020] For example, the connecting elements are cast, rolled, and stamped in an upstream manufacturing process. The steel pots are preferably cast, rolled, stamped, and formed. The steel pots are an example of connecting elements that, in centrifugal casting, extend not only radially but also axially into the formed shell element.

[0021] According to a further preferred embodiment of the method according to the invention, the second material comprises gray cast iron. Preferably, the second material consists of gray cast iron. In this way, a shell element is created that exhibits high wear resistance. In addition, gray cast iron has suitable castability and is easy to process. Furthermore, mechanical vibrations are well dampened in a brake drum whose shell element comprises gray cast iron.

[0022] The term "grey cast iron" is understood by those skilled in the art to preferably mean an iron-carbon alloy with a carbon content of > 2%, in which the carbon occurs in the form of graphite.

[0023] In a further preferred embodiment of the method according to the invention, the connecting elements are held within the die assembly by means of core elements during centrifugal casting. This ensures that the connecting elements are held within the die assembly particularly reliably during centrifugal casting.

[0024] Preferably, the connecting elements are pre-embedded in the core elements by a core shooting process. The connecting elements, joined to the core elements, are then inserted into the die casting mold as a composite piece for centrifugal casting. The core elements preferably consist of core sand.

[0025] In a preferred embodiment of the above-described design, the core elements extend at least partially in a radial direction to the axis of rotation into core bearing recesses of the mold assembly. This simplifies the process flow. The core bearing recesses define the positioning of the connecting elements pre-embedded in the core elements. This facilitates the positioning of the connecting elements within the mold assembly.

[0026] Preferably, the core bearing recesses form a rib-like structure along the inner surface of the mold assembly.

[0027] In a further preferred embodiment of the method according to the invention, the connecting elements have recesses designed to receive wheel bolts when the vehicle is mounted. During centrifugal casting, the connecting elements are held within the mold by means of rod elements extending through the recesses. This makes the process particularly simple and easy to handle. Several connecting elements can be mounted on the rod elements and held in position during centrifugal casting. The time-consuming process of encasing the connecting elements in core sand is eliminated.

[0028] The phrase "designed for receiving wheel bolts in a vehicle-mounted state" is understood by a person skilled in the art to mean that the respective connecting element is mounted in a vehicle as part of the brake drum using the wheel bolts. A further recess in the connecting element is provided for receiving a wheel axle during installation in the vehicle. In a vehicle-mounted state, the connecting element rotates around the axis of rotation of the wheel axle.

[0029] The rod elements are preferably held by flange elements, which are inserted into a corresponding recess in the mold device at the end faces of the mold device.

[0030] According to a further preferred embodiment of the inventive method, a brake drum blank is produced by separating the intermediate brake drum material into at least two sections, each having a connecting element. This represents a particularly suitable embodiment of the inventive manufacturing method. Centrifugal casting simplifies the inventive method in particular, since the outer shell extends over several connecting elements. Separating the intermediate brake drum material is a particularly simple and intuitive step in producing the brake drum blank.

[0031] In a preferred further development of this embodiment, an internal friction surface is formed on the outer shell element of the brake drum blank. This creates a friction surface suitable for use in a vehicle. This embodiment is based on the understanding that the inner surface of the outer shell element is uneven after centrifugal casting and cutting, and therefore unsuitable for use as a friction surface during braking.

[0032] Preferably, the machining process is carried out by removing unevenness or pores, in particular by sandblasting, grinding, etc., as part of the so-called casting finishing.

[0033] The aforementioned problem is further solved by an intermediate brake drum product which is manufactured using a process of the type described above.

[0034] The aforementioned problem is further solved according to the invention by a brake drum having the features of claim 9. Accordingly, the brake drum is manufactured in a method of the type described above.

[0035] The aforementioned problem is further solved according to the invention by a vehicle with the features of claim 10. Accordingly, the vehicle has a brake drum of the type described above.

[0036] The vehicle is preferably a passenger transport vehicle. More preferably, the vehicle is a passenger car. In this case, the vehicle has, for example, four brake drums, namely one brake drum at each wheel.

[0037] For advantages, embodiments and design details of the brake drum and the vehicle according to the invention, reference can be made to the preceding description of the corresponding features of the method for manufacturing a brake drum for a vehicle.

[0038] Exemplary embodiments of the invention are further explained below with reference to the drawings. These show: Fig. 1 a connecting element for a first embodiment of a brake drum according to the invention in a top view, Fig. 2 a further connecting element for a second embodiment of a brake drum according to the invention, Fig. 3 a schematic flowchart according to a first and second embodiment of a method according to the invention, Fig. 4 a first arrangement of an intermediate brake drum product, which is used in the first embodiment of the method according to the invention, Fig. 5 a second arrangement of a brake drum intermediate product, which is used in the second embodiment of the method according to the invention, and Fig. 6 a brake drum blank, which is used in the first and second embodiments of the method according to the invention.

[0039] Fig. Figure 1 shows a schematic top view of a connecting element 1, which is formed as a stamped steel sheet 2. The connecting element 1 has four recesses 3 in the form of through holes, which are intended for receiving wheel bolts. To attach the connecting element 1 to the vehicle, the wheel bolts are inserted through the through holes and firmly connected to the vehicle by means of the wheel bolts. A further recess 4 is provided for receiving a wheel axle. When mounted in the vehicle, the connecting element 1 rotates about the axis of rotation 5 of the wheel axle. The area of ​​the connecting element 1 around the recesses 3 and 4 forms a mounting section 7 at which the connecting element 1 can be mounted to a vehicle. The steel for the steel sheet 2 forms a first material from which the connecting element 1 is at least partially formed.

[0040] The connecting element 1 also has several tooth sections 6 which extend essentially in a radial direction to the axis of rotation 5 outwards.

[0041] Fig. Figure 2 shows a perspective view of a mounting element 11, which is designed as a formed steel pot 12. The mounting element 11 has four recesses 13, which protrude to receive wheel bolts. The mounting element 11 is attached to a vehicle by means of these wheel bolts. A further recess 14 is provided for receiving a wheel axle. When mounted in the vehicle, the mounting element 11 rotates about the axis of rotation 15 of the wheel axle.

[0042] The connecting element also has several tooth sections 16 which extend essentially in an axial direction to the axis of rotation 15.

[0043] The sequence of a first and second embodiment of the inventive method for manufacturing a brake drum is shown schematically in Fig. 3 shown. The differences between the two embodiments are explained in Fig. 3 graphically represented as two branches that can be executed after process step B.

[0044] In process step A, the connecting element 1 is manufactured. For this purpose, a steel sheet is produced and the Fig. 1. Shape shown with cutouts 3 and 4 and tooth sections 16 punched out.

[0045] In process step B, several connecting elements 1 are provided for processing according to the inventive method.

[0046] In process step C, the connecting elements 1 are pre-embedded in core elements using a core shooting process.

[0047] In process step D, the connecting elements 1, which are connected to the core elements, are inserted as a composite piece into an open mold casting device for centrifugal casting.

[0048] Fig. Figure 4 shows a sectional view of a molding device 20 into which several connecting elements 1 are inserted in conjunction with core elements 21, which consist of core sand. The core elements 21 penetrate the connecting elements 1 at corresponding recesses, for example at the in Fig. 1. shown recesses 3.

[0049] The core elements 21 ensure that the connecting elements 1 are held at a predetermined distance from each other. In other words, the connecting elements 1 are arranged at a predetermined distance d from each other during centrifugal casting. Furthermore, the core elements 21 cause the connecting elements 1 to extend radially in the direction R towards an axis of rotation 25 into a shell element 26 formed during centrifugal casting.

[0050] The in Fig. The shape of the core elements 21 shown in Figure 4 can be varied as desired to achieve corresponding casting shapes, for example with chamfers, bevels, rib structures, etc. (provided the resulting casting shape can be cored without undercuts). It is not necessary for the core elements 21 to extend completely around the entire circumference of the connecting element 1. Instead, the core elements 21 can be formed at several points spaced apart in the circumferential direction.

[0051] The mold assembly 20 has several core bearing recesses 27 along its longitudinal extent, into each of which a core element 21 extends in the radial direction R. The core bearing recesses 27 ensure a predetermined positioning of the core elements 21 within the mold assembly 20. In this way, the connecting elements 1 are held at a predetermined distance d from each other.

[0052] The outer shell element 26 is produced in process step E by centrifugal casting of gray cast iron within the mold 20. During centrifugal casting, the mold 20 rotates about the axis of rotation 25. The liquid gray cast iron is poured into the mold 20 as a second material via an inlet. The centrifugal force generated by the rotation causes the second material to be deposited and solidify on the inner wall of the mold 20. The centrifugal casting produces an intermediate brake drum assembly 30, which comprises the connecting elements 1 and the outer shell element 26.

[0053] In process step F, the intermediate brake drum part 30 is removed from the mold 20. To produce a brake drum blank 32, the intermediate brake drum part is cut in process step G. This is done by cutting edges whose course is Fig. 4 is shown as dividing lines 31. After separation along dividing line 31, each brake drum blank 32 has a connecting element 1.

[0054] Before or after process step F, core removal or desanding also takes place, in which the core elements 21 are removed.

[0055] An embodiment of a brake drum blank 32 is shown in Fig. 6 shown. That in Fig. The outer shell element 26 of the intermediate brake drum 30, shown in Figure 4, was cut to form a shell element 36 of the brake drum blank 32. In process step H, the inner surface 33 of the shell element 36 of the brake drum blank 32 is machined to form a friction surface 34. When installed in the vehicle, the friction surface 34 serves to press brake shoes against the drum.

[0056] A second embodiment of the method according to the invention is carried out similarly to the first embodiment. Identical and functionally equivalent elements are used in Fig. 5 with the same reference symbols as in Fig. 4 provided.

[0057] Fig. Figure 5 shows a sectional view of a mold assembly 40 into which several connecting elements 1 are inserted. The connecting elements 1 are held within the mold assembly 40 by means of rod elements 41 and 42. For this purpose, the rod elements 41 and 42 extend through the recesses 3 of the connecting elements 1. The rod elements 41 and 42 are held by flange elements 44 and 45, which are inserted into corresponding recesses 48 and 49 on the end faces 46 and 47 of the mold assembly 40.

[0058] Accordingly, process steps A, B, and F to H in the second embodiment of the inventive method are carried out in the same manner as in the first embodiment. Process steps C to E differ in that, in the second embodiment, the connecting elements 1 are placed on the rod elements 41 and 42 in process step CC and distributed at a predetermined distance d from one another. In process step DD, the connecting elements 1, which are mounted on the rod elements 41 and 42, are inserted as a composite piece into the open mold device 40 for centrifugal casting.

[0059] In process step EE, the outer shell element 26 is produced by centrifugal casting of gray cast iron within the die casting device 20. During centrifugal casting, the die casting device 40 rotates about the axis of rotation 25. The centrifugal casting produces an intermediate brake drum part 30, which comprises the connecting elements 1 and the outer shell element 26.

[0060] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be derived by the person skilled in the art without leaving the scope of protection of the invention. Reference symbol list 1 connecting element 2 steel sheets 3 exceptions 4 Exclusion 5 Rotation axis 6 tooth sections 7 Assembly step 11 Connecting element 12 steel pots 13 exceptions 14 Exclusion 15 Rotation axis 16 tooth sections 20 mold setup 21 core elements 25 Rotation axis 26 Shell element (brake drum intermediate product) 27 core storage recesses 30 Brake drum intermediate product 31 dividing lines 32 Brake drum blank 33 internal surface 34 friction surface 36. Casing element (brake drum blank) 40 mold setup 41, 42 Bar element 44, 45 Flange element 46, 47 Front 48, 49 Exclusion A process step B Procedure step C, CC Process step D, DD process step E, EE process step F Process step G Process step H Process step R radial direction d distance QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2011 054 484 A1

[0003] EP 3 314 141 B1

[0004]

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