BRAKING DEVICE FOR MACHINING BEARING COVERS
FIELD OF THE INVENTION The present invention relates to devices for securing a wheel bearing cap or other bearing caps in a CNC work center.
BACKGROUND OF THE INVENTION The bearing caps are used to secure a bearing that gives movement or articulates an axis. The bearing caps are used in vehicles in order to retain the axles in the vehicle frame and the wheel bearings for the wheel assembly. The bearing caps could also be provided to retain the crankshaft bearings in a motor and could also be used in other types of machinery. Generally, the bearing caps have a semicircular body portion and flanges for receiving screws that are used to secure the bearing cap on a support member or a second part of a bearing retainer assembly. The bearing caps have to be machined in strict tolerances to avoid mounting problems and excessive leftovers and the waste material expense. The bearing caps could be formed in a
REF. 186157
smelting operation in which tolerances are required to be normally maintained at ± 0. 08 centimeters (± 0. 03 0 inches) for foundries that have a distance between the points measured between 0 and 7. 62 centimeters (0 and 3 inches) and ± 1. 14 centimeters (± 0.45 inches) between 7. 62 and 20. 32 centimeters (3 and 8 inches). The foundries are usually configured with a lateral angle of inclination that is required to remove the cast iron from the casting mold. The unusual shape of the bearing cap makes it difficult to properly secure one or more bearing caps as they are machined. Normally, the bearing caps have to be machined after the casting process in order to provide uniformity from part to part. For example, in a central machining position, a bearing cap can be clamped while the screw holes are drilled and rebounded or widened in the holding brackets of the bearing cap with the end faces of the bearing cap that They are milled to a tolerance of ± 0. 03 centimeters (± 0. 010 inches). The relatively wide tolerance for a cast-iron bearing cap is three times the allowed tolerance for surface machining, which makes it difficult to hold the molten bearing caps during the initial machining operations. Once they are
After initial machining operations on the bearing cap have been performed, exactly machined surfaces are available to locate the bearing cap for subsequent machining operations. There is a need for a device for machining a plurality of bearing caps simultaneously in a work center that allows the positions and machined surfaces of the screw hole to be located exactly. The above problems and needs are addressed through the invention of the Applicant as summarized below.
SUMMARY OF THE INVENTION According to one aspect of the invention, there is provided a fastener device for machining a plurality of bearing caps, which is easy for it to accurately load and hold the bearing caps to form the screw holes and the milled surfaces. According to another aspect of the invention, a fastening device for a bearing cap is centered relative to a generally semi-cylindrical surface of the "freshly fused" rough part. The generally semi-cylindrical surface could be the bearing hole of a bearing cap. The bearing hole engages with a mandrel of the fastener device having a corresponding center
with the center of the bearing that will be retained by the bearing cap. The clamps or clamps engage with the outer surface of the bearing cap held in order to retain them on the mandrel. The screw holes and the machined surfaces are located relative to the partially cylindrical surface corresponding to the inner hole of the bearing cover which receives the bearing. According to another aspect of the invention, a fastening device for machining a bearing cap is provided which allows a plurality of bearing caps to be held relative to the radius fused ends of the bearing cap. The floating V-shaped blocks that can be rotated and displaced could position, in one embodiment, the ends of the bearing cap. The V-floating blocks could be spring-loaded to move up and down and also to rotate in order to compensate for the lateral tilt angle and the tolerances of the casting part. V-floating blocks facilitate loading and also increase the part-to-part uniformity for machining operations. According to other aspects of the present invention, the bearing caps are retained by clamping plates which lock the bearing cap in the clamping device before performing the desired operations of
machined The clamping plates locate the bearing caps in the device in predetermined positions, and in particular, they keep the bearing caps on the semicircular center radius of casting in the desired circumferential orientation relative to the mandrel. According to another aspect of the invention, a method for the manufacture of bearing caps using an improved device for "freshly fused" parts is described. A rugged bearing cap is emptied into a mold having a semi-cylindrical bearing bore and a freshly fused outer surface. Next, a plurality of bearing caps are assembled in a first device having a mandrel that is received in the bearing hole. The bearing caps are assembled on the first device with clamps that engage with the outer surface of the bearing caps. A pair of screw support portions of the bearing caps are machined and the screw hole is drilled in each screw support portion. The bearing caps are removed from the first device and subsequently machined while they are located using the screw holes to form the finished bearing caps. These and other characteristics and advantages will be better understood in view of the attached figures and the following
detailed description of the illustrated embodiment of the invention.
BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a front elevation view of a device for machining bearing caps in a CNC work center shown with the bearings held in the device according to one embodiment of the present invention; Figure 2 is a cross-sectional view taken along line 2-2 in Figure 1; Figure 3 is a cross-sectional view similar to Figure 2 showing a bearing cap before being assembled in the device; Figure 4 is an exploded perspective view of a V-shaped floating block made in accordance with an embodiment of the present invention; Figure 5 is a schematic cross-sectional view showing the degrees of freedom of movement of the floating block-V; Figure 6 is an exploded fragmentary perspective view of a mandrel and a clamp according to an aspect of the present invention; Figure 7 is a perspective view of a molded non-machined molded bearing cap; Y
Figure 8 is a perspective view of a partially machined bearing cap.
DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1, there is shown a device 10 for retaining a plurality of bearing caps 12 with ten bearing caps assembled in the device 10. The device 10 includes two side plates 16, a plate of base 18 and a top plate 20. Generally, the device 10 has the shape of an open frame which allows machining operations to be carried out on two sides of the bearing caps 12 while they are assembled in the device 10. A mandrel 22 extends between the side plates 16 and parallel to the base plate 18 and the top plate 20. The plates and the mandrel of the frame are assembled together by centering pins (not shown) and socket screws 24. A V-26 floating block upper assembly is assembled in the upper plate 20 of the device 10. A lower V-floating block fastener assembly 28 is assembled in the base plate 18 of the device 10. Each of the V-block assemblies 26, 28 includes a jaw 30 that is mounted on a pin 32. A spring 34 elastically biases the jaw 30 relative to the retainer
block-V 3 6. The pin 32 is articulated within the V-block retainer 36 which supports the jaw 30 in a movable relation to the V-block retainer 36. A locking screw 40 and a nut 42 are used to secure the mandrel bracket 38. The locking screw 40 extends through the mandrel 22 between two adjacent bearing caps 12, so that a single clamp 38 could be used to engage with two adjacent bearing caps 12 in order to retain the bearing caps 12 in the device 10. With reference to Figures 2 and 3, the relationship of the bearing cap 12, the mandrel 22 and the upper and lower V-block assemblies 26, 28 are illustrated. The mandrel 22 is secured between the side plates 16. The locking screw 40 is retained by a back plate 44 which holds the locking screw 40 securely within the screw head housing 46. The screw head receptacle 46 is configured to receive the head of the locking screw 40 in a non-rotating relationship. The locking screw 40 is received in a screw hole 48 formed in the mandrel 22. The locking screw 40 is also received in a central hole 50 of the mandrel bracket 38. The mandrel clamp 38 includes locating fingers 52 that engage with a step 54 that is formed on a flange of
reinforcement 56 of the bearing cover 12. A tubular extension 58 is formed on the chuck clamp 38 and is received in a clamp receptacle hole 59. The clamp receptacle orifice 59 could have a polygonal configuration, such as a square configuration that locates the clamp 38 in a non-rotating mode. A pin receptacle 60 is provided in the V-block retainer 36 which receives the pin 32 and holds the pin 32 fixed relative to the V-block retainer 36. A slot 64 is provided in the jaw 30. The slot is elongated in the vertical direction. The term "vertical direction" as used herein is the direction defined by a line extending perpendicular to the base plate 18 and the top plate 20. The clamp 3 0 receives the pin 32 in the slot 64, so that the clamp 30 can move in the vertical direction and can also rotate relative to the V-block retainer 36. The spring 34 is received in a spring seat 66 formed in the V-block retainer 36 and a spring receptacle 68 formed in the jaw 30. The spring 34 deflects the clamp 30 towards the mandrel 22. A locating surface 70 of the jaw 30 is oriented to engage with the outer surface 72 of the bearing cap 12. The outer surface 72 is formed with a lateral tilt angle in the casting process
in which the bearing cap 12 is initially emptied. The jaw 30 can be rotated relative to the V-block retainer 3 6 and can also be moved in a vertical direction relative to the V-block retainer 36 to accommodate variations that arise from the normal tolerances in the size and shape of the block. the bearing cover 12. When the bearing cap 12 is clamped, the bearing cap is engaged through the upper V-block assembly 26 and the lower V-block assembly 28 which retains the bearing cap relative to the mandrel 22 with the bearing hole 76, freshly cast, and clutching with the cylindrical surface 78 that are formed on the mandrel 22. Once the bearing cap 12 is placed between the upper and lower block-V assemblies 26, 28 and the mandrel 22, the mandrel clamp 38 is placed on the locking screw with the locating fingers 52 engaging with the steps 54 of the bearing cover 12. Next, the nut 42 is used to secure the mandrel clamp 38 in the locking screw 40. The tubular extension 58 of the mandrel clamp 38 is received in the clamp receptacle hole 59. With reference to Figure 4, the structure and function of the upper V-block assembly 26 are described in greater detail. It should be understood that the lower clamp 28 floating assembly has the same structure and function
than the top assembly of V-block 26. The upper V-block assembly 26 is assembled on the upper plate 20. In Figure 4, two V-block retainers 36 are shown secured in the upper plate 20. A jaw 30 is shown oriented ready for assembly in the V-block retainer 36 with a second jaw 30 which is shown assembled in the V-block retainer 36. The spring 34 is received in the spring seat 66 which is formed in the V-block retainer 36. The spring 34 is received in the spring seat 66 which is formed in the V-block retainer 36. The centering means 32 extends through the centering holes 60 formed in the V-block retainer 36. The centering means 32 also extends through the groove 64 formed in the jaw 30. The location surface 70 of the jaw 30 is oriented to engage with the outer surface 70 of the end 74 of the bearing cap 12, as described above. With reference to Figure 5, the movable mounting arrangement of the jaw 30 is shown to illustrate the available degrees of freedom of movement of the jaw 30. The V-block retainer 36 is secured in the upper plate 20. The clamp 3 0 is secured in the V-block retainer 36 through the centering pin 32. The circular centering means 32 allows limited rotational movement of the jaw 30 in relation to the V-block retainer 36. The movement
longitudinal or vertical of the jaw 30 is allowed by means of the elongated slot 64 formed in the jaw 30. When the bearing cap 12 is initially inserted into the device, the outer surface 72 of the bearing cap 12 is received through the the locating surface 70 of the jaw 30. The jaw 30 could move in a rotational and vertical fashion to accommodate variations in the bearing cap 12. The jaws 30 initially hold the bearing cap 12 adjacent the mandrel 22. The spring 34 provides a biasing force against the outer surface 72 of the bearing cap 12. With reference to Figure 6, the mandrel 22 and the mandrel clamp 38 are illustrated so as to show how the mandrel clamps 38 are secured. in the mandrel 22. The mandrel 22 has screw head receptacles 46 which receive the head of the locking screw 40, so that it can not rotate after insertion into the screw head receptacle 46. The locking screw 40 is held in the mandrel 22 by the back plate 44 which is secured by means of the screws 24 in the mandrel 22. As shown in Figure 6, a locking screw 40 is shown secured within the mandrel and a second locking screw 40 is shown partially assembled on the mandrel 22 with the backing plate 44 which is oriented for
its assembly in the mandrel 22. As shown in Figure 6, the mandrel clamp 38 is oriented for mounting with the locking screw 40. The mandrel clamp 38 has locating fingers 52 which are oriented to engage with a step 54 on the bearing cap 12. A central hole 50 is drilled through the mandrel bracket 38 which extends through the tubular extension 58 of the mandrel bracket 38. The locking screw 40 receives the mandrel clamp 38, so that the locking screw extends through the central hole 50. With reference to Figure 7, a bearing cap is shown in its cast configuration. The bearing cap 12 includes a reinforcing flange 56 on which the step 54 is formed which is engaged through the locating fingers 52 of the mandrel bracket 38. Two faces or surfaces 74 are fused at opposite ends of the bearing 12. The outer surfaces 72 of the bearing cap 12 engage with the locating surface 70 of each of the jaws 30. The piece to be manufactured from machine 80 is provided on the bearing cap 12 which is machined in the CNC work center with a cylindrical milling cutter, or the like, in order to form a machined parting line 82. The screw supports 74 are also machined while being formed on the
device with screw hole 3 4 through screw holder 7 4. A reamer hole 8 6 is formed on the screw holder 7 4 to provide a machined surface that is concentric with the screw hole 8 4 on the opposite side of the bearing cap 1 2 of the partition melt line 8 0. The screw hole 84 and the reamer hole 8 6 could be formed in a single step with a suitable combination drill. With reference to Figure 8, a machined bearing cap 1 2 'is illustrated. The machined bearing cap 1 2 'is machined with the milling cutter of the partition line 8 0 to the desired machined line of partition 8 2. The machined bearing cap 1 2' has also been machined on the opposite side of the line of partition by drilling a screw hole 8 4 through the screw holder 7 4 and reaming a reamer hole 8 6. While the embodiments of the invention have been illustrated and described, these embodiments are not intended to illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood
that several changes could be made without departing from the spirit and scope of the invention. It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.