Title of Invention

AN IMPROVED CNC TOOL AND CUTTER GRINDING MACHINE

Abstract

Disclosed herein with 5 axes Computer operated numeric control (CNC) and cutter grinding machine with specific axes configuration with specific design of guard, in order to completely isolate the grinding area from all machine elements. This isolation totally avoids the ingress of coolant and grinding dust to various machine elements like Linear Motion (LM) guides, ball screws, electrical motors, limit switches etc., thereby considerably increasing the life of these machine elements and reducing the machine breakdowns. As the hot coolant does not come in contact with any machine elements, the thermal stability of the machine improves thereby ensuring the high accuracy of the tools produced on the machine.

Full Text

INTRODUCTION This invention relates to development of an improved 5 axes Computer operated numeric control (CNC) tool and cutter grinding machine with specific axes configuration with specific design of guard, in order to completely isolate the grinding area from all machine elements. This isolation totally avoids the ingress of coolant and grinding dust to various machine elements like Linear Motion (LM) guides, ball screws, electrical motors, limit switches etc., thereby considerably increasing the life of these machine elements and reducing the machine breakdowns. As the hot coolant does not come in contact with any machine elements, the thermal stability of the machine improves thereby ensuring the high accuracy of the tools produced on the machine. BACKGROUND OF THE INVENTION Conventional CNC tool and cutter grinding machines make use of extensive coolant jets for carrying away the heat and grinding dust generated while grinding. It is well known that wet grinding produces better quality cutting surfaces of tools. However, wet grinding has two main disadvantages as far as the machine tool elements are concerned. 1. The grinding coolant comes in contact with rotating wheel and generates mist. The large quantity of coolant mixed with grinding dust and mist falls on all the machine elements and over a period of time enters inside critical elements like LM guides, (guidance of linear axes), ball screws, bearings, limit switches etc, despite conventional protection elements like bellow, telescopic covers etc. This ingress of coolant and grinding dust is detrimental to accuracy of functioning of these elements and results in rapid wear out and premature failure of these elements. As a result the overall accuracy of the machine is severely affected and frequent breakdowns reduce the effective utilization of these highly expensive machines. 2. The coolant after absorbing grinding heat has higher temperature compared to other machine elements. This coolant when comes in contact with machine elements causes thermal deformations of the elements and this adversely affects the accuracies of tools manufactured/resharpened on these machines. In order to minimize these thermal effects higher capacity conventional refrigeration systems have to be used to control coolant temperatures. The present invention overcomes both the above disadvantages by providing the following features: a. The CNC axes are organized in specific configuration; b. The linear axis and rotary axis are placed in such a way that complete separation is provided between the grinding area and all the machine elements; c. The coolant is prevented by coming in contact with any of the critical machine elements; and d. The machine elements are provided with specially designed labyrinth seals to prevent ingress of coolant in the bearing area. Accordingly, it is an object of the present invention to provide an improved computer operated numeric control (CNC) tool and cutter grinding machine in order to completely separate the grinding area from all machine elements. To achieve this, the CNC axes are organized in a specific way. It is a further object of the present invention to collect the coolant in the coolant tank provided right below the grinding zone to avoid the coolant coming in contact with the machine elements. In a further embodiment, labyrinth seals are provided on the machine elements such as the grinding spindle, work head axis to prevent ingress of coolant in the bearing area. This invention will now be described with reference to the accompanying drawings, wherein; Fig. 1 shows the elevational view of the machine layout; Fig.2 shows the end view of the machine layout; Fig.3 shows the X and Z assembly; Fig.4 shows the cross sectional view of the work spindle along the A-axis; Fig.5 shows the cross sectional view of the slide assembly along the Y-axis; and Fig.6 shows the cross sectional view of the grinding spindle assembly. Persons skilled in the art will be able to understand the layout of the CNC machine and accordingly, we describe herein below only the modifications that are effected and not the full CNC machine. In the drawings, the various parts are referred to by the reference numerals as given herein below: Reference numeral 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. Machine parts Machine guard LM guides Ball screws Bearings Servo motors Moving gear for (X & Z) Partition sheet (For X & Z) Electrical motors Limit switches Grinding zone Linear slides Rotary table Machine base 14. Grinding spindle 15. Inner labyrinth 16. Outer labyrinth 17. Bearings area 18. Case iron shde (Zone) 19. Z axis LM rail 20. X axis slide 21. Not marked 22. A axis spindle 23. A axis bearings 24. WormAVorm wheel 25. A axis housing 26. Y axis colimm 27. Y axis LM rail 28. Y axis LM block 29. Partition sheet (for Y axis) 30. Y axis moving cover 31. Spindle mounting bracket 32. Integral motor spindle 33. Labyrinth (Inner) 34. Labyrinth (Outer) The highlights of design features of the above elements are as given below: a) As shown in fig.3, the combination slide (X, Y) consists of C.I slide (18) which is supported on the LM blocks on LM rails (19) provided on machine base. The X slide (20) is designed as a long slide, which is fitted with LM rail, and it moves on LM blocks fitted on Z slide (18). This design construction helps in projecting the grinding point away from the X and Z axis elements like ball screws, limit switches, LM guides etc (3,8,2). b) A axis (work piece rotation) (ref Fig.4) is designed as a long spindle (22) which is supported on precision bearings (23) and is driven by worm and worm wheel (24) at rear end. The A axis is fitted on X axis slide with the help of screws from below to prevent entry to coolant thro' the open screw holes. The long housing of A axis (25) mounted on overhanging X slide (20) makes it possible to provide a partition between grinding area (10) and elements of A, X, Z axis. The details of partition design are explained in fig.l (7). c) Vertical slide Y-axis is mounted on a stationary column (26) of stepped design (Ref. Fig.5). Y-axis has moving LM rail (27) and fixed LM block (28) construction to facilitate over hanging Y slide. B axis rotary table is fitted on Y slide, A fixed cover sheet (29) is provided between Y slide and column to isolate Y elements from coolant zone. Y-axis slide has been provided with moving cover (30), which protects all elements of B axis rotary table. All electrical and coolant lines leading to spindle pass through B axis and spindle mounting bracket (31). This eliminates usage of hoses etc., which cause obstructions during grinding operations. d) Integral motor spindle (14) (fig.6) fitted on B axis table is provided with special labyrinth type seals (16) which offer multi layer protection to bearings against coolant and mist. The different layers of protection are as follows: 1. Ring (15) fitted on spindle diverts major amount of splash away bearings. from 2. Front cover (16) collects the coolant that enters through the gaps between rotating elements of spindle and stationary end gaps. 3. Gap seal (32) provides additional protection against coolant entry inside spindle. 4. Labyrinth seals (33) and (34) provide final protection layer. The entry of coolant inside spindle is thus completely prevented, e) Isolation of Grinding zone The construction of all the above mentioned machine elements ensure that the two partition sheets, i.e., (X-Z) axis sheet (7) and Y axis sheets (29), joined together form a completely enclosed grinding zone which totally contains the grinding dust, coolant and mist. The X-Z partition incorporates a specially designed moving cover (6), which facilitates movement of A axis in X and Z directions. f) The machine base (13) which supports all machine elements is a fabricated construction & has provision to collect the coolant right below the grinding zone. The coolant is directed to the coolant tank. This design of machine base ensures that coolant does not come in contact with any of the machine elements. This ensures good thermal stability of the machine. CONCLUSION The specific combination of CNC axes, (XZA and YB) specific overhang type construction of XZY axes, completely isolated grinding zone and collection of coolant right below the grinding zone and the completely protected spindle are the main features of the invention, which help, in improved reliability of these type of machines. Unique features of this invention are: 1. The construction of XZA and Y-axes, which facilitates creation of completely, enclosed grinding area. 2. The construction of enclosed grinding area including a) design of special cover (7) for A axis which allow movement in x and z direction and b) moving cover (30) of Y axis which protects all elements of B axis and spindle. 3. Design of machine base (13), which allows collection of coolant right below guiding area. 4. Labyrinth seal design for spindle protection. WE CLAIM: 1. In a known CNC tool and cutter grinding machine having linear axes XYZ and rotary axes A & B and having grinding spindle and coolant system, the improvement comprising: A) i) a combination slide (X,Z) supported by Linear Motion blocks fitted on Linear Motion rails (19) provided on machine base, an X slide (20) which is long, being fitted with Linear Motion rail (19) movable on the Linear Motion blocks so as to project the grinding point away from the X and Z axis elements; ii) An 'A' axis in the form of a long spindle (22) supported on precision bearings (23), the said spindle being driven by worm & worm wheel (24) at rear end of the spindle, the said axis being fitted on the X-axis slide so as to prevent entry of coolant therein; iii) Vertical slide Y-axis is mounted on a stationary column (26), the said axis having a moving Linear Motion rail (27) and fixed Linear Motion block (28), B) i) a ring (15) is fitted on spindle to divert the splash away from bearings; ii) Integral motor spindle (14) fitted on B axis tables is provided with labyrinth type seals (16); iii) a gap seal (32) is provided on the grinding spindle assembly for preventing the ingress of coolant & dust and C) a separate tray being provided on the base (13) to divert all the coolant to the coolant tank without coming in contact with the machine base.

Documents:

338-mas-1998 correspondence others 20-01-2011.pdf

338-mas-1998 correspondence others 20-01-2011.pdf

338-mas-1998 form-1 20-01-2011.pdf

338-mas-1998 form-13 20-01-2011.pdf

338-mas-1998 form.13 20-01-2011.pdf

338-mas-1998 power of attorney 20-01-2011.pdf

338-mas-1998-abstract.pdf

338-mas-1998-claims filed.pdf

338-mas-1998-claims granted.pdf

338-mas-1998-correspondnece-others.pdf

338-mas-1998-correspondnece-po.pdf

338-mas-1998-description(complete) filed.pdf

338-mas-1998-description(complete) granted.pdf

338-mas-1998-description(provisional).pdf

338-mas-1998-drawings.pdf

338-mas-1998-form 1.pdf

338-mas-1998-form 26.pdf

338-mas-1998-form 3.pdf

338-mas-1998-form 5.pdf

338-mas-1998-other documents.pdf