DESC:FIELD OF INVENTION

The present invention relates to grinding machines performing engine machining function. In particular, the present invention relates to camshaft grinding machines. More particularly, the present invention relates to movable cradle support for loading components to be worked on the grinding machine.

BACKGROUND OF THE INVENTION

In any automobile manufacturing plant, numerous facilities are provided as part of its various component manufacturing lines, since a large number of automotive components are manufactured there for various automobile variants and models. Camshaft is one of the major components used in automotive industry. Cam grinders are used to make camshafts. A cradle is used for supporting the component on a cam grinder. There are different types of customized cam grinders in practice, however these conventional cam grinders do not provide an efficient cradle support.

PRIOR ART

CA 2221102 A1 discloses a method of supporting a workpiece having journal and eccentric regions, in a grinding machine for grinding the eccentric regions thereof, is described which involves mounting the workpiece in a headstock of the grinding machine, providing a coupling between the workpiece and a rotary drive mechanism for rotating the workpiece about its main axis and fitting around at least one remote journal region of the workpiece a pair of members which form a journal bearing complementary to the said region, and fixing the lower of the two members to the machine, thereby providing support for the workpiece at the said remote position. The method is particularly relevant to the grinding of crankpins of a camshaft.

A grinding machine for grinding the crankpins of a crankshaft workpiece comprises headstock means mounted on the machine bed, a grinding wheel mounted on a wheel head assembly, drive means for moving the wheel head towards and away from a workpiece when fitted to the headstock, drive means for rotating a workpiece when mounted in the headstock, and two part cradle means mounted in the machine at least one part of which presents at least an upwardly directed curved support surface for engaging the underside of a journal bearing region of a crankshaft workpiece when fitted to the headstock.

US2017927 A discloses cam grinding machine. The headstock and tailstock are mounted upon swinging cradle. Swinging motion for cradle is provided by cam roller. Further cam roller is shifted by piston cylinder mechanism

US2243410 A discloses a grinding machine comprising a work support, a wheel support, means for rotating a work piece on said woork support, means for effecting a relative transverse movement between said supports, means responsive to said transverse movement for changing the speed of said work rotating means at the beginning of a grinding operation, and a control mechanism operable before the end of the grinding operation for changing said work speed back to the initial rate. Here, the work carriage is slidably mounted on it. cam shaft is rotatably supported on work carriage between the headstock and the tailstock. Further, A work cradle is pivotally mounted on carriage which rotatably supports a master cam in axial alignment with work piece of cam shaft.

DISADVANTAGES WITH THE PRIOR ART

Different types of customized camshaft grinding machines are available in the market. However, the disadvantage with the cradle supports for loading the components to be worked on the such camshaft grinding machines is that these machines are not versatile, flexible and complex during camshaft grinding operations.

Although, there are several prior art documents related to cam grinding machines, such configurations do not provide unidirectional up or down movement of the cradle axes for holding components in dis-assembled condition on a cam grinding machine.

OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide a versatile, flexible and complex during camshaft grinding machine.

Another object of the present invention is to provide a cam grinding machine, which is safe and efficient for performing camshaft grinding operations.

Still another object of the present invention is to provide a movable cradle support for a camshaft grinding machine, which moves in a unidirectional manner.

Yet another object of the present invention is to provide a movable cradle support for a camshaft grinding machine, which properly holds the components to be worked thereon.

A still further object of the present invention is to provide a movable cradle support for a camshaft grinding machine, which can be easily adapted to different camshaft variants based on their varying diameters and/or lengths.

A yet further object of the present invention is to provide a movable cradle support for a camshaft grinding machine, which is offers a cost-effective automation.

These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.

SUMMARY OF THE INVENTION

In accordance with an embodiment of the present invention, there is provided a movable cradle mechanism for grinding machine having a cradle assembly and a pneumatic cylinder-piston assembly, in which the cradle assembly comprises a profiled cradle fitted on the tie rod connected to the pneumatic cylinder-piston assembly and a guide rod fixed parallel to the tie rod and disposed under the cradle for moving the cradle in a unidirectional vertical movement thereof to avoid any transverse movement of the cradle and thereby prevent any damage to the component to be ground on the grinding machine.

Typically, the component to be worked on the grinding machine is a crankshaft.

Typically, the guide rod slides inside a pair of guide bushes mutually spaced apart and fitted on upper and lower edges of the cylinder of the cylinder-piston assembly.

Typically, the cradle supporting the crankshaft is moved upwards for clamping the crankshaft between the centers of the headstock and tailstock.

Typically, the cradle supporting the crankshaft is moved downwards after de-clamping the crankshaft from the centers of the headstock and tailstock after completion of the grinding thereof.

Typically, the cradle comprises a profile complementing the camshaft profile.

Typically, a proximity switch is attached to the cradle for identifying the camshaft model to be ground on the grinding machine, according to the desired shifting position of the cradle for adjusting the vertical distance required to be travelled by the cradle.

In accordance with another embodiment of the present invention, there is provided a moveable cradle mechanism for grinding machine having a cradle assembly and a pneumatic cylinder-piston assembly, characterized in that the cradle assembly comprises a profiled cradle fitted on the tie rod connected to the pneumatic cylinder-piston assembly and a guide rod fixed parallel to the tie rod and disposed under the cradle for moving the cradle in a predefined unidirectional vertical movement thereof according to the camshaft model to be worked on the grinding machine in order to avoid any transverse movement of the cradle and thereby to prevent any damage to the camshaft for grinding thereof supported on the cradle.

Typically, a proximity switch is attached to the cradle for identifying the camshaft model to be ground on the grinding machine, according to the desired shifting position of the cradle.

Typically, the guide rod slides inside a pair of guide bushes mutually spaced apart and fitted on upper and lower edges of the cylinder of the cylinder-piston assembly.

DESCRIPTION OF THE INVENTION

In contrast to disclosure in CA 2221102 A1, the present invention configures the cradle to move in just one axis (i.e. unidirectional by means of a Guided Cylinder Mechanism).

Further, the one or more movable cradles move simultaneously across the longitunical axes to hold the component properly during dismantled condition and the movable craddle assembly / assemblies shift/s automatically to different upper and lower positions according to the different camshaft variants (based on the diameters and/or lengths thereof) by sensing on camshaft body using proximity sensor.

Similarly, as against the disclosure in US2017927 A, the present invention uses an upper and lower position according to different camshaft variants (based on the diameters and/or lengths thereof) by sensing on camshaft body using proximity sensor.

Unlike US2243410 A, the present invention also includes a unidirectional guided cylinder mechanism in single axis only instead of complete rotation.

Accordingly, the present invention seeks to address this problem by improving the cam grinding operation to make it safe and efficient by moving the cradle unidirectionally.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings, wherein:

Figure 1 shows a movable cradle mechanism configured in accordance with the present invention and assembled with a conventional pneumatic cylinder for a camshaft grinding machine.

Figure 2a shows a schematic arrangement of the grinding machine equipped with a conventional pneumatic movable cylinder and depicted in a lower position of the movable cradle mechanism configured in accordance with the present invention.

Figure 2b shows a schematic arrangement of the grinding machine configured with a movable cylinder in an upper position of the movable cradle mechanism configured in accordance with the present invention.

Figure 3 shows a schematic diagram of the cradle support having a guided cylinder mechanism moving unidirectionally in along a single axis.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The movable cradle for a camshaft grinding machine configured in accordance with the present invention will be described below in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.
Figure 1 shows a movable cradle mechanism configured in accordance with the present invention and assembled with a conventional pneumatic cylinder 20 for a camshaft grinding machine 100. It includes a cradle 10 fitted on the cylinder tie-rod 26 by means of a nut 12. The cylinder tie rod 26 is passing through the cylinder body 21 and sliding inside a piston spool 23 and extends through the cylinder body 21 through a seal 25 for sealing purpose. The cylinder body 21 is provided with an opening port 27 and an inlet port 29 each on the upper and lower sides of the cylinder body 21, which are provided with a respective adjusting screw 15 for adjusting opening port 27.

Figure 2a shows a schematic arrangement of the grinding machine 100 equipped with a conventional pneumatic movable cylinder 20 and assembled with a movable cradle mechanism configured in accordance with the present invention. The cylinder 20 is depicted in a lower position D of a moveable cradle 10. The camshaft 30 is clamped centered between the headstock 40 and tailstock 50 by means of the centers 45, 55 thereof for camshaft grinding. In order to prevent the cam run-out on the base circle diameter thereof, in the position shown here, the movable cradle 10 is brought down under the camshaft 30 after loading the crankshaft 30 for grinding operation.

Figure 2b shows another view of the grinding machine 100 equipped with a conventional movable cylinder 20 and assembled with a movable cradle mechanism configured in accordance with the present invention. Here, the cradle 10 is brought in an upper or raised position U for freely supporting the crankshaft 30 for supporting the same to de-clamp it from the center 45 of the headstock 40 and the center 55 of the tailstock 50. The direction B shows the backward movement of the tailstock 50 for de-clamping the crankshaft from the centers 45, 55.

Figure 3 shows a schematic diagram of the cradle support arrangement having the cylinder mechanism 20 guided unidirectionally along a single (vertical) axis. It shows the cradle 10 supported by a cylinder mechanism 20 consisting of a guide rod 22 vertically moving inside a pair guide bushes 24, a tie rod 26 capable of making an upward or downward movement and a proximity switch 28 provided for identifying different variants of camshaft 30 for grinding operation on the grinding machine 100.

WORKING OF THE INVENTION

Conventionally, while setting the cradle height, the gap between the component (cam shaft) and the cradle is set at 0.1 mm. When the camshaft rotates during the grinding operation, there is fouling of the cradle 1 due to projections on the core diameter, batch code, heat code and fused sand. Due to this fouling, the camshaft base circle run-out increases, which results in the leakage of the cylinder head valve and unwanted rejection of the camshafts. During its movement, the cradle may move transverse to this axis, which can damage the camshaft body. In order to avoid the fouling of the camshaft on the fixed cradle, a unique solution in the form of the moveable cradle mechanism configured in accordance with the present invention facilitates the cradle 10 to be moved unidirectionally upwards or downwards along a single vertical axis X-X.

When the camshaft 30 is held between the tailstock centre 55 and the work driver centre 45, the movable cradle 10 should move down (Fig.2a). In contrast, when the camshaft 30 is not held by the tailstock centre 55 and work driver centre 45 (Fig.2b), the cradle 10 should move upward, for holding the camshaft 30 during the grinding operation and in a disengaged condition (i.e. when head stock 40 and tail stock 50 are not clamped).

When the camshaft 30 is clamped, the cradle movement occurs in a downward direction (Fig. 2a) with the help of the cylinder piston arrangement (Figure 3).

Accordingly, a tie rod 22 is provided, which is guided inside the guide bushes 24 to move the cradle 10 to ensure a unidirectional movement of the cradle 10 upward or downward to prevent any transverse movement of the cradle 10. A proximity switch 28 is also attached to the cradle 10 for identification of different models of camshafts 30 according to the respective shifting positions thereof. In all, three or more cradles can also be attached along the longitudinal axis to simultaneously perform the same operation.
TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The movable cradle support for loading components to be worked on the grinding machine configured according to the present invention has the following advantages:

• Eliminates engine rejections due to cam shaft run-out on base circle dia.

• No camshaft fouling with the cradle due to flexibility.

• Zero camshaft rejection due to the absence of cradle fouling with the camshaft core diameter.

• Unskilled personnel can set the cradle.

• Simple in design and can be made in-house.

• Offers a low-cost automation.

• Versatile and flexible.

• Several different camshaft models can be identified for their correct positioning.

• Handy and easy to make by available machines and to operate.

• Very cost-effective.

• Generates a fault (machine Interlock provided with PLC logic controller), if the up or down movement of the cradle fails in cycle.

• Generates an alarm as the cradle up or down unidirectional movement is fed into the logic circuit, if cradle up-down movement fails in cycle.

• Synchronizes all cradles movements.

• Auto-movement of the cradle can be set as per different cradle variants.

The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention. The description provided herein is purely by way of example and illustration.

Although, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification by making innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.

While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention.

These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Many of the fastening, connection, processes and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art and they will not therefore be discussed in significant detail.

The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

Also, any reference herein to the terms ‘left’ or ‘right, ‘up’ or ‘down, or ‘top’ or ‘bottom’ are used as a matter of mere convenience, and are determined by standing at the rear of the machine facing in its normal direction of travel.

Furthermore, the various components shown or described herein for any specific application of this invention can be widely known or used in the art by persons skilled in the art and each will likewise not therefore be discussed in significant detail. When referring to the figures, like parts are numbered the same in all of the figures. ,CLAIMS:We claim:

1. A movable cradle mechanism for grinding machine having a cradle assembly and a pneumatic cylinder-piston assembly, characterized in that the cradle assembly comprises a profiled cradle fitted on the tie rod connected to the pneumatic cylinder-piston assembly and a guide rod fixed parallel to the tie rod and disposed under the cradle for moving the cradle in a unidirectional vertical movement thereof to avoid any transverse movement of the cradle and thereby prevent any damage to the component to be ground on the grinding machine.

2. Movable cradle mechanism as claimed in claim 1, wherein the component to be worked on the grinding machine is a crankshaft.

3. Movable cradle mechanism as claimed in claim 2, wherein the guide rod slides inside a pair of guide bushes mutually spaced apart and fitted on upper and lower edges of the cylinder of the cylinder-piston assembly.

4. Movable cradle mechanism as claimed in claim 2, wherein the cradle supporting the crankshaft is moved upwards for clamping the crankshaft between the centers of the headstock and tailstock.

5. Movable cradle mechanism as claimed in claim 2, wherein the cradle supporting the crankshaft is moved downwards after de-clamping the crankshaft from the centers of the headstock and tailstock after completion of the grinding thereof.

6. Movable cradle mechanism as claimed in claim 2, wherein the cradle comprises a profile complementing the camshaft profile.

7. Movable cradle mechanism as claimed in claim 2, wherein a proximity switch is attached to the cradle for identifying the camshaft model to be ground on the grinding machine, according to the desired shifting position of the cradle for adjusting the vertical distance required to be travelled by the cradle.

8. A movable cradle mechanism for grinding machine having a cradle assembly and a pneumatic cylinder-piston assembly, characterized in that the cradle assembly comprises a profiled cradle fitted on the tie rod connected to the pneumatic cylinder-piston assembly and a guide rod fixed parallel to the tie rod and disposed under the cradle for moving the cradle in a predefined unidirectional vertical movement thereof according to the camshaft model to be worked on the grinding machine in order to avoid any transverse movement of the cradle and thereby to prevent any damage to the camshaft for grinding thereof supported on the cradle.

9. Movable cradle mechanism as claimed in claim 8, wherein a proximity switch is attached to the cradle for identifying the camshaft model to be ground on the grinding machine, according to the desired shifting position of the cradle.

10. Movable cradle mechanism as claimed in claim 8, wherein the guide rod slides inside a pair of guide bushes mutually spaced apart and fitted on upper and lower edges of the cylinder of the cylinder-piston assembly.