US3694971A

US3694971A - Guard system for high speed grinder

Info

Publication number: US3694971A
Application number: US68114A
Authority: US
Inventors: Howard W Renner; John A Moores
Original assignee: Milacron Inc
Current assignee: Milacron Inc
Priority date: 1970-08-31
Filing date: 1970-08-31
Publication date: 1972-10-03
Anticipated expiration: 1989-10-03
Also published as: DE2126259A1; GB1334172A; FR2106032A5; SE391887B

Abstract

A first shield is disposed above a workpiece and adjacent thereto to protect the operator of a grinding machine during a grinding operation from any fragments of an exploding grinding wheel. During loading and unloading of the workpieces, the first shield is pivoted away from the grinding position of the workpiece, and a second shield is disposed between the workpiece and the grinding wheel to protect the operator during loading and unloading operations. The first shield has a coolant supplied thereto for cooling the grinding wheel; this coolant serves as an energy absorber if any fragment of an exploding grinding wheel strikes the first shield.

Description

United States Patent Renner et al.

[is] 3,694,971 [451 Oct. 3, 1972 1 GUARD SYSTEM FOR HIGH SPEED GRINDER [72] Inventors: Howard W. Renner; John A.

Moores, both of Cincinnati, Ohio [73] Assignee: Cincinnati Milacron lnc., Cincinnati, Ohio 22 Filed: Aug. 31, 1970 211 Appl. No.: 68,114

[52] US. Cl. ..51/267, 51/269, 51/272 [51] Int. Cl ..B24b 55/02, B24b 55/04 [58] Field of Search ..51/269, 268, 267, 266, 272,

51/356; 143/159 R, 159 M, 159 N; 144/251 [56] References Cited UNITED STATES PATENTS 1,694,340 12/1928 Weinland ..51/268 1,208,186 12/1916 Middleton ..51/269 3,452,489 7/1969 Kallander ..51/269 3,129,537 4/1964 Backer ..51/166 MI-l 1,286,518 Brassill ..51/268 1,512,889 10/1924 Henry ..51/267 3,564,780 5/1969 Grzymek et al. ..51/269 3,571,983 3/1971 Stewart et a1 ..51/269 1,259,050 3/1918 Scofield ..51/272 1,447,996 3/1923 Muehlhauser ..5 1/ 272 2,315,132 3/1943 Powers ..51/272 Primary Examiner-Donald G. Kelly Attorney-Frank C. Leach, Jr.

[57] ABSTRACT A first shield is disposed abovea workpiece and adjacent thereto to protect the operator of a grinding machine during a grinding operation from any fragments of an exploding grinding wheel. During loading and unloading of the workpieces, the first shield is pivoted away from the grinding position of the workpiece, and a second shield is disposed between the workpiece and the grinding wheel to protect the operator during loading and unloading operations. The first shield has a coolant supplied thereto for cooling the grinding wheel; this coolant serves as an energy absorber if any fragment of an exploding grinding wheel strikes the first shield.

16 Claims, 14 Drawing Figures PATENTEDUBT 3 I972 SHEET 1 0F 7 INVENTOR5 HOWARD w. RENNEB JOHN mamas M MA ATTORNEY PAIENTED [1813 c912 SHEET b 0F 7 PATENTEDnm 3 m2 SHEET 5 [IF 7 PATENTEDnm 3 I972 SHEET 6 [IF 7 Wm w GUARD SYSTEM FOR HIGH SPEED GRINDER In high speed grinding, the energy of the grinding wheel is so high that a great danger exists to the operator of the grinding machine if a grinding wheel should blow up because of the speed imparted to any fragments of the grinding wheel from the high energy of the grinding wheel. Therefore, it is necessary that the operator be protected from these fragments during operation of the high speed grinding machine.

It should be understood that the grinding wheel explodes or blows up due to improper mounting, im proper use, or improper handling after leaving the manufacturer. There is no failure of the grinding wheel because of its manufacture but only when there is a failure by the user to mount, use, or handle the grinding wheel properly.

While the grinding wheel probably will .blow up during grinding of a workpiece, it is possible for the grinding wheel to explode during the time when the grinding wheel is withdrawn from the workpiece to allow unloading of the ground workpiece and loading of another workpiece. Therefore, the operator should be protected not only during the grinding of the workpiece but also during the loading and unloading thereof.

It has previously been suggested in the copending patent application of Rolf T. Grzymek et al. for Operator-Protective shield, Ser. No. 822,119, filed May 6, 1969, now U.S. Pat. No. 3,564,780, and assigned to the same assignee as the assignee of the present application, to use a protective shield to surround the front portion of the grinding wheel of a high speed grinding machine. Thus, the structure of the aforesaid Grzymek et al. application is one suitable means for preventing fragments of a high speed grinding wheel from striking the operator when the grinding wheel explodes.

The guard system of the present invention also satisfactorily protects the operator from fragments of an exploding grinding wheel. The present invention enables the workpiece to be more easily removed and another workpiece substituted therefor than the arrangement in the aforesaid Grzymek et al. application.

In the present invention, a first protective shield or door, which is disposed adjacent the top of the workpiece and extends upwardly therefrom, is pivoted out of the position in which it would affect the loading and unloading of workpieces. Thus, the present invention satisfactorily protects the operator during grinding without affecting the loading and unloading of workpieces.

The first protective shield or door of the present invention has a coolant flowing through the interior.

thereof to the grinding wheel and the workpiece. This coolant functions as an energy absorber when any fragment of an exploding grinding wheel strikes the shield. The movement of the first shield is limited by fixed rails.

While the first shield of the present invention is pivoted out of the position in which it would affect the loading and unloading of workpieces during loading and unloading, this shield would be returned to its position adjacent the workpiece when struck by any fragment of an exploding grinding wheel to prevent the fragments from escaping from the grinding machine to strike the operator. However, if manual, rather than automatic, loading and unloading of the workpieces is employed, the operators hand may be positioned on the top of the workpiece, for example, where it could be cut off by the rapid movement of the shield due to any fragmentof the exploding wheel.

Accordingly, the present invention utilizes a second shield or door, which is disposed .between the first shield and the workpiece position during loading and unloading of the workpieces. The second shield is supported so that it does not move when the first shield is moved against the second shield by any fragment of the exploding grinding wheel striking the first shield during loading and unloading whereby the hand of the operator is not cut off or otherwise harmed by the movement of the first shield.

Therefore, the second shield protects the operator during manual loading and unloading in particular. Of course, the second shield could be employed with automatic loading and unloading as the operator may still position his hand adjacent the workpiece even during automatic loading and unloading.

The present invention also uses a shield between the workpiece and the operator. Therefore, if the workpiece should be knocked loose from its supports by any fragment of the exploding grinding wheel, the workpiece would be prevented from striking the operator by the workpiece shield.

The present invention is particularly contemplated for use with the guard system of the type shown and described in the copending patent application of Irving J. Stewart et al. for Guard System, Ser. No. 822,120, filed May 6, 1969, now U.S. Pat. No. 3,571,983, and assigned to the same assignee as the assignee of the present application. In the aforesaid Stewart et al. application, rigid closed cell energy dissipators are employed with a grinding wheel guard around the rear portion of the grinding wheel. Thus, the system of the aforesaid Stewart et al. application enables the energy of a blown-up grinding wheel 'to be absorbed rearwardly through fragments of the grinding wheel striking the rigid closed cell energy dissipators. This cooperates with the protective guard system of this invention to insure that the grinding wheel fragments do not escape from the grinding machine.

An object of this invention is to provide a protective guard system for the operator of a high speed grinding machine.

Another object of this invention is to provide a protective guard system for a grinding machine in which the workpieces may be easily loaded and unloaded.

Other objects of this invention will be readily perceived from the following description, claims, and drawings.

This invention relates to a grinding machine having a base on which is supported a wheel slide for translational movement relative to a workpiece to be ground. The slide supports a grinding wheel and a guard, which substantially encloses the grinding wheel. The grinding machine has means cooperating with the grinding wheel and disposed above the workpiece to prevent any fragments of the grinding wheel in the event of a failure of the grinding wheel from escaping between the top of the workpiece and the guard. Means moves the cooperating means to a workpiece loading position toward the grinding wheel when the grinding wheel is withdrawn from engagement with the workpiece by the slide for loading and unloading of workpieces.

The attached drawings illustrate preferred embodiments of the invention, in which:

FIG. 1 is a perspective view of a grinding machine utilizing the guard system of the present invention;

FIG. 2 is a side elevational view, partly in section, showing the guard system of the'present invention;

. FIG. 3 is an enlarged sectional view of the structure of FIG. 1 with the grinding wheel engaging the workpiece and taken along line 3-3 of FIG. 1;

FIG. 4 is a sectional view, similar to FIG. 3, but with the grinding wheel retracted and the other elements in the workpiece loading and unloading position;

FIG. 5 is a sectional view showing means for retaining a coolant shield in a desired position and taken along line 5-5 of FIG. 4;

FIG. 6 is a front elevational view, partly in section, of the guard system of FIG. 3 and taken along line 6-6 of FIG. 3;

FIG. 7 is a sectional view, partly in elevation, of the guard system of FIG. 3 and taken along line 7-7 of FIG. 3;

FIG. 8 is a sectional view, partly in elevation, of the guard system of FIG. 3 and taken along line 8-8 of FIG. 3;

FIG. 9 is a sectional view of a first shield of the guard system of FIG. 3 including its mountingarrangement and taken along line 9-9 of FIG. 3;

FIG. 10 is a rear elevational view, partly in section, of a portion of the guard system of FIG. 3 and taken along line 10-10 of FIG. 3;

F IG. 11 is a fragmentary rear elevational view of a portion of the guard system of FIG. 3 and showing the mounting of the vertical side walls of the guard system to a machine base of the grinding machine;

FIG. 12 is a top plan view, partly in section, of the guard system of FIG. 3 and taken along line 12-12 of FIG. 3;

FIG. 13 is a sectional view, similar to FIG. 3, but showing a different type of workpiece protective guard shield for the guard system of the present invention; and

FIG. 14 is a schematic wiring diagram of a control system for use with the guard system of the present invention.

Referring to the drawings and particularly FIG. 1, there is shown a grinding machine having a support or base 10 on which is slidably supported a wheel slide or wheel head 11 (see FIG. 2). A grinding wheel spindle 12 (see FIG. 3) is rotatably supported by the slide 11 and has a grinding wheel 14 fixed to one end thereof. The other end of the spindle 12 is connected in the well known manner to a drive motor 13 for rotating the grinding wheel 14.

The slide 11 has a grinding wheel guard 15 supported thereon for cooperation with the grinding wheel 14 in the manner more particularly shown and described in the aforesaid Stewart et al. application. The grinding wheel guard 15 has rigid closed cell deformable means 16 to absorb some of the energy from the fragments of the grinding wheel 14 if it should blow up.

The rigid closed cell deformable means 16 are supported in the grinding wheel guard 15 in the manner more particularly shown and described in the aforesaid Stewart et al. application. As mentioned in the aforesaid Stewart et al. application, one suitable example of the material of the rigid closed cell deformable means 16 is polyurethane foam.

The base 10 has spaced rear walls 17 and 18 (see FIGS. 1 and 12) extending upwardly therefrom to form an opening 18 (see FIGS. 11 and 12) therebetween through which the grinding wheel 14 extends. The rear wall 17 has a side wall 19 secured thereto by suitable means such as welding, for example, and extending forwardly therefrom. The rear wall 18 has a side wall 20, which is substantially parallel to the side wall 19, connected thereto by suitable means such as welding, for example, and extending forwardly therefrom.

A plate 20a (see FIG. 11) is secured to the bottom surface of the rear wall 17 and to the side surface of the side wall 19 by suitable means such as welding, for example. The plate 200 has a plate 20b, which is connected to the bottom surface of the plate 20a by suitable means such as welding, for example, extending downwardly therefrom for attachment to the base 10 by screws 20c.

The plate 20b has ribs 20d secured thereto and to the bottom surface of the plate 20a by suitable means such as welding, for example. The lower end of the side wall 19 also is formed similar to the ribs 20d and is attached to the plate 20b by suitable means such as welding, for example. The side wall 19 also has a bracket 20e (see FIGS. 7 and 12) welded thereto and attached to the base 10 by screws. Accordingly, the rear wall 17 and the side wall 19 form a unitary assembly, which is connected to the base 10.

The rear wall 18 and the side wall 20 are secured to the base 10 in the same manner as described for the rear wall 17 and the side wall 19. The various connecting portions are identified by the same numerals as have been used for the elements connected to the rear wall 17 and the side wall 19.

A top plate 21 is secured to the tops of the

side walls

19 and 20 and to the tops of the rearwalls 17 and 18. As shown in FIGS. 2 to 4, the plate 21 extends over the top of the guard 15.

The workpiece 22 is supported between a headstock 23 and a footstock 24 in the well known manner. The headstock 23 is driven by a headstock drive 25 (see FIG. 1) in the well known manner. This rotates the workpiece 22 during the grinding thereof.

The guard system of the present invention includes a primary door or shield 26 (see FIGS. 3 and 4), which has its upper end extending through a slot 27 in the top plate 21 and connected to a piston rod 28 of a hydraulic cylinder 29. The cylinder 29 is pivotally mounted on a bracket 30, which is fixed to the top plate 21. Accordingly, when fluid is supplied to one end of the hydraulic cylinder 29, the piston rod 28 is extended to pivot the shield 26 counterclockwise about a hollow hinge pin 31. The hinge pin 31 is supported on blocks 31' (see FIG. 9), which are fixed to the top plate 21.

The shield 26 is formed of a thick front plate 32 and sheet metal means 33, which comprises a plurality of members forming the top wall and the side walls of the shield 26. The sheet metal means 33 cooperates with the plate 32 to form a chamber 34 therebetween. A coolant fluid is introduced into the chamber 34 through a longitudinal slot 34' in the lower portion of the hollow hinge pin 31.

When the piston rod 28 has been retracted into the cylinder 29, the shield 26 is held in the position of FIGS. 2 and 3 where the front plate 32 of the shield 26 abuts against rails or blocks 35 and 36, which are supported by the

side walls

19 and 20, respectively. In this position, the coolant flows from the chamber 34 through an opening or nozzle 37 (see FIG. 3) at the lower end of the shield 26 onto the grinding wheel 14 adjacent the workpiece 22.

Accordingly, as shown in FIG. 3, the shield 26 prevents any fragment of the grinding wheel 14 from escaping between the workpiece 22 and the top plate 21 since the lower end of the shield 26 is disposed adjacent the top of the workpiece 22. The coolant, which is flowing through the chamber 34 in the shield 26, serves as an energy absorber for any fragment of the grinding wheel 14, if it explodes, that collapses the sheet metal means 33.

Because of the position of the base relative to the workpiece 22 and the counterclockwise (as viewed in FIG. 3) rotation of the grinding wheel 14, fragments of the grinding wheel 14, if it blows up, are not able to escape beneath the workpiece 22 either. However, the force of the fragments of the grinding wheel 14, if it explodes, has sufficient energy to displace the workpiece 22 from its support by the headstock 23 and the footstock 24. Accordingly, it is necessary to protect the operator from the workpiece 22 in this situation.

A workpiece deflector 38 is disposed between the supports (the headstock 23 and the footstock 24) for the workpiece 22 and the operator. The workpiece deflector 38 includes a thick plate 39. One side of the thick plate 39 is disposed between a bar 40 (see FIG. 10), which is supported on the side wall 20, and a block 41 (see FIGS. 6 and 12), which is spaced from the bar 40 and also supported on the side wall at its front edge. The other side of the thick plate 39 is supported between a bar 42 (see FIG. 10), which is supported on the side wall 19, and a block 43 (see FIGS. 6 and 12), which is spaced from the bar 42 and also supported on the side wall 19 at its front edge.

The blocks 41 and 43 are of substantially the same length as the thick plate 39 of the deflector 38. Accordingly, if the workpiece 22 should be driven against the workpiece deflector 38 by the grinding wheel 14 exploding and having a fragment knock the workpiece 22 loose from its supports (the headstock 23 and the footstock 24), the force is transmitted from the deflector 38 through the plate 39 to the blocks 41 and 43, which have substantially the same length as the plate 39.

The workpiece deflector 38 also includes a member 44, which is fixed to the plate 39. The member 44 extends from the plate 39 to deflect downwardly the workpiece 22 if it should be removed from its supports by any fragment from the grinding wheel 14, if it explodes, that moves upwardly. The member 44 is supported by a plurality of ribs 45, which are triangular shaped.

The opposite side of the plate 39 has a sheet metal member 46 secured thereto in spaced relation thereto by ribs 47. The member 46 adds rigidity and strength to the deflector 38 to prevent the workpiece 22 from penetrating the deflector 38 to injure the operator. As shown in FIG. 12, the sides of the member 46 extend beyond the

side walls

19 and 20 to aid in retaining the coolant within the machine.

A handle 48 is secured to the sheet metal member 46 to raise and lower the deflector 38. However, the

deflector 38 is lifted upwardly only during a major overhaul.

A coolant shield 49, which is pivotally mounted on pins 50 supported by the

side walls

19 and 20, is disposed above the workpiece deflector 38. The shield 49 includes a transparent member 51, which may be made of Plexiglas, for example.

The shield 49 prevents any coolant from spraying exterior of the grinding machine onto the operator. The shield 49 must be swung out of the way whenever there is to be manual loading and unloading of the workpieces 22.

The coolant shield 49 is limited from being pivoted exteriorly of the position shown in FIG. 3 by rails 52, which are supported on each of the

vertical side walls

19 and 20 as shown in FIGS. 6 and 12. The coolant shield 49 is held in each of the positions of FIGS. 3 and 4 by catches 53.

As shown in FIG. 5, each of the catches 53 includes a resiliently biased plunger 54, which cooperates with a recess 55 in the coolant shield 49. Thus, the coolant shield 49 is retained in either the position of FIG. 3 or the position of FIG. 4.

The rigid closed cell deformable means 16 also absorbs energy from fragments of the grinding wheel 14, if it explodes, in the manner more particularly shown and described in the aforesaid Stewart et al. application. Thus, the shield 26 serves to protect the operator during grinding of the workpiece 22 if the grinding wheel 14 should explode.

When the workpiece 22 is to be replaced by another of the workpieces 22, it is necessary to retract the grinding wheel 14 away from the workpiece 22 by retracting the wheel slide 11. When the wheel slide 11 completes its retraction, fluid is supplied to the hydraulic cylinder 29 to pivot the shield 26 counterclockwise about the hinge pin 31. This moves the shield 26 to the position of FIG. 4 wherein there is a space between the workpiece 22 and the shield 26.

During manual loading, the operator may position his hand on top of the workpiece, which is being loaded or unloaded, for example, to change the workpiece. If the grinding wheel 14 should blow up at this time, the fragments of the grinding wheel 14 would strike the shield 26 with sufficient energy to move the shield 26 rapidly against the

blocks

35 and 36. As a result of the shield 26 moving to this position with the high velocity or force, the hand of the operator would be easily severed if it were disposed in the path of the shield 26.

Accordingly, when using the guard system of the present invention in which manual loading and unloading-is employed, a second door or shield is employed. The shield 60 is a curved plate, which has its opposite sides connected to pivotally mounted

arms

61 and 62.

The arm 61 is connected to a rotary actuator 63 (see FIGS. 6 and 7) while the arm 62 is connected to a rotary actuator 64. When the

rotary actuators

63 and 64 are rotated in one direction, the shield 60 is moved to the position shown in FIG. 4 in which it is disposed between the workpiece 22 and the shield 26. When the

rotary actuators

63 and 64 are rotated in the opposite direction, the shield 60 is returned to the inactive position in which it is disposed above the workpiece 22 as shown in FIG. 3.

The

rotary actuators

63 and 64 are energized to move the second shield 60 to the position between the first shield 26 and the workpiece 22 after the shield 26 is pivoted counterclockwise about the pin 31 to the position shown in FIG. 4. Thus, the second shield 60 is not moved until the first shield 26 is in its retracted position.

The second shield 60 passes through a curved slot 65 (see FIG. 7) in the rail 36 to swing between its two positions. As shown in FIG. 7, there is a jog in the arm 61 so that the second shield 60 clears the rail 35 during pivoting between the two positions. While it is desired that the space between the

arms

61 and 62 be as large as possible to permit loading and unloading of the workpieces 22, the arm 61 must have the jog therein to avoid engaging a headstock workpiece driver 66.

When the second shield 60 is disposed in the position of FIG. 4, safety catches 67 on the first shield 26 engage the second shield 60 if the grinding wheel 14 explodes and fragments strike the first shield 26 during loading and unloading of the workpieces 22 to move it forward toward the second shield 60. The L-shaped safety catches 67 engage over the top end of the second shield 60 when the first shield 26 is moved forward by being struck by a fragment of the exploding grinding wheel 14; this results in the second shield 60 being locked in the position of FIG. 4.

Since the

rotary actuators

63 and 64 are supported on the

side walls

19 and 20 by brackets 68 (see FIGS. 6 and 7), the

arms

61 and 62 have sufficient strength to normally prevent the second shield 60 from being moved toward the workpiece 22 by the first shield 26 being moved due to the grinding wheel 14 exploding. However, the energy of the fragments of the exploding grinding wheel 14 may be sufficient to cause shearing of the pivot pins for the

arms

61 and 62.

When this occurs, the

arms

61 and 62 are moved into V-shaped notches, which are formed between the bar 40 and a wedge 69a (see FIG. and between the bar 42 and a wedge 69b (see FIGS. 3 and 10). The wedges 69a and 69b are supported on the side walls and 19, respectively. Thus, the

bars

40 and 42 not only form part of the guide for the deflector 38 but also function to prevent the

arms

61 and 62 from moving into engagement with the deflector 38 if the shear pins for the

arms

61 and 62 should fail.

When loading of the new workpiece 22 is completed, the second shield 60 is returned to the position of FIG. 3 by energization of the

rotary actuators

63 and 64. After the second shield 60 reaches the position of FIG. 3, fluid is supplied to the hydraulic cylinder 29 to retract the piston rod 28 into the cylinder 29 whereby .the first shield 26 is pivoted clockwise about the hinge pin 31 until the blocks or rails 35 and 36 are engaged by the front plate 32 of the first shield 26. Upon the shield 26 engaging the blocks or rails 35 and 36, the grinding wheel 14 is fed toward the workpiece 22 for grinding.

Referring to FIG. 14, the sequence of operation of a complete automatic grinding cycle will be described. A cycle is started by activating a cycle start push button 70.

At this time, the footstock 24 has its center retracted to the workpiece loading position in which another of the workpieces 22 has been loaded between the headstock 23 and the footstock 24. In this retracted position of the center of the footstock 24, the footstock center holds a limit switch 71 in an open position.

At this time, the first shield 26 is in its retracted position so that a limit switch 72 is closed. Since the wheel slide 11 is in its retracted position, a portion 73a of a limit switch is open and a portion 73b of the limit switch is closed. Since the second shield 60 is rotated to the position of FIG. 4 between the workpiece support position and the grinding wheel 14, a limit switch 74 is closed. Furthermore, a gauge head.(not shown) also is in its retracted position whereby a limit switch 75 is closed. I

When the cycle start push button 70 is closed, a control relay 76 is energized only when a limit switch 77 is closed due to the coolant shield 49 being in its closed position of FIG. 3. Therefore, the coolant shield 49 must be closed before the cycle can start.

A circuit is completed from a line 79 to a line 80 through the closed limit switch 77, a cycle stop push button 81, the closed cycle start push button 70, normally closed contacts 82-1 of a control relay 82, and a portion 83a of a limit switch. The limit switch portion 83a is moved to an open position only when the wheel slide 11 is at its grinding position at which time a portion 83b of the limit switch is closed.

The picking of the control relay 76 causes its normally open contacts 76-1 to close whereby a hold cirnormally open contacts 76-2 to close whereby a solenoid 84 is energized. The activation of the solenoid 84 causes the center of the footstock 24 to be moved to the position in which it holds the workpiece 22 in cooperation with the headstock 23 for grinding.

When the center of the footstock 24 is moved from its retracted position, the limit switch 71 is released and returned to its closed position. Upon the center of the footstock 24 firmly holding the workpiece 22 for grinding, a limit switch 85 is closed to complete a circuit through a solenoid 86 to cause the

rotary actuators

63 and 64 to return the second shield 60 to the position of FIG. 3 wherein the second shield 60 does not prevent grinding of the workpiece 22 by the grinding wheel.

As the second shield 60 is moved from the position in which it is disposed between the workpiece 22 and the grinding wheel 14, the limit switch 74 is returned to its open position. When the second shield 60 reaches the position of FIG. 3, a limit switch 87 is actuated to complete a circuit through a solenoid 88. The energization of the solenoid 88 results in fluid being supplied to the hydraulic cylinder 29 to pivot the first shield 26 clockwise about the pin 31 to the position of FIG. 3. It also starts the flow of coolant to the chamber 34 in the first shield 26.

When the first shield 26 leaves its retracted position, the limit switch 72 is released and opens. Upon the first shield 26 pivoting clockwise to the position of FIG. 3, a limit switch 89 is closed to supply a signal to a stock removal system to indicate that all of the necessary machine element motions have been completed to prepare for the grinding operation. One suitable example of the stock removal system is more particularly shown and described in the copending patent application of Howard W. Renner et al. for Method And Apparatus For Automatic Grinding, Ser. No. 778,208, filed Nov. 22, 1968, now U.S. Pat. No. 3,599,376, and assigned to the same assignee as the assignee of the present application.

If the stock removal system has its normally open contacts 90 closed to indicate that the stock removal system is in the feed retracted position so that the grinding cycle may start, the closing of the limit switch 89 causes energization of a solenoid 91 and a control relay 92 through a closed limit switch 93 and the closed contacts 90. When the control relay 92 is picked, a hold circuit for the control relay 92 is completed through normally open contacts 92-1 of the control relay 92 being closed and the closed limit switch 93. This enables the grinding cycle to continue even though the normally open contacts 90 of the stock removal system again open due to the stock removal system leaving its retracted position at the start of its normal travel.

The energization of the solenoid 91 causes the wheel slide 11 to be advanced rapidly from its retracted position to its grinding position. When the wheel slide 11 begins its forward movement, the limit switch portion 73a is released so that it closes and completes a circuit from the line 79 through normally open contacts 76-3, which are closed, of the control relay 76 and the control relay 82 to the line 80. As a result, the control relay 82 is energized. The energization of the control relay 82 closes its normally open contacts 82-2 to complete a hold circuit for the control relay through the closed limit switch 71 and the contacts 82-2.

When the control relay 82 is activated, its normally open contacts 82-3 also close. Since the energization of the control relay 92 resulted in closing of its normally open contacts 92-2, which are in series with the contacts 82-3, a circuit is completed to the

solenoids

84, 86, 88, and 91 that bypasses the contacts 76-2 of the control relay 76. This is necessary since the control relay 76 is inactivated when the wheel slide 11 reaches its grinding position because of the opening of the limit switch portion 83a. Since this occurs shortly after energization of the control relay 82, the circuit to the

solenoids

84, 86, 88, and 91 must be provided through the contacts 82-3 and 92-2.

In addition to opening the limit switch portion 83a, the movement of the wheel slide 11 to its grinding position also closes the limit switch portion 83b. This disposition of the wheel slide 11 at its grinding position also causes a signal to be supplied to the stock removal system to indicate that the stock removal system can commence its own sequence of functions.

At some predetermined time during the stock removal system function sequence, a signal is produced to advance a sizing gauge head (not shown) to the position in which it measures the workpiece 22. When this signal is produced, normally open contacts 95 of the stock removal system are closed so that a solenoid 96 is energized.

The activation of the solenoid 96 moves the gauge head forward to the position in which the gauge head measures the size of the workpiece 22. When the gauge head is advanced from its retracted position, the limit switch 75 returns to its open position. However, the

limit switch portion 73b is still open because the wheel slide 11 is at its grinding position so that none of the

solenoids

97, 98, and 99 can be activated at this time even though normally open contacts 82-4 of the energized control relay 82 are closed.

During the forward movement of the gauge head to its workpiece measuring position, normally open contacts 100 of the stock removal system are closed. When the gauge head reaches the workpiece measuring position, the limit switch 93 is opened but the circuit to the solenoid 91 and the control relay 92 is maintained through the contacts 100 and the contacts 92-1 of the control relay 92.

As long as the workpiece 22 is larger than the finished workpiece dimension that is set into the gauge adjustment of the gauge head, the contacts 100 remain closed. However, as soon as the gauge of the gauge head registers the finished workpiece dimension, the contacts 100 open.

When this occurs, the solenoid 91 is de-energized, and the control relay 92 is inactivated. The de-energization of the solenoid 91 causes rapid retraction of the wheel slide 11 to its retracted or non-grinding position while the inactivation of the control relay 92 stops coolant flow to the chamber 34 in the first shield 26.

The dropping ofthe relay 92 results in the normally open contacts 92-2 opening whereby the

solenoids

84, 86, 88, and 96 are inactivated. The de-energization of the solenoid 96 causes retraction of the sizing gauge head from the workpiece 22. The de-energizations of the

solenoids

84, 86, and 88 do not produce any machine functions because of the connections of the

solenoids

84, 86, and 88 to the hydraulic control valves.

As the wheel slide 11 retracts from its grinding position, the limit switch portion 83b is opened and the limit switch portion 83a is closed. However, even though the limit switch portion 83a closes, the control relay 76 cannot be picked because the cycle start push button is in an open position and the contacts 82-1 of the control relay 82 are open. When the wheel slide 11 completes movement to its retracted position, the limit switch portion 3a is opened and the limit switch portion 73b is closed.

When the gauge head retracts from its measuring position, the limit switch 93 is again closed. When the gauge head completes it movement to its retracted position, the limit switch is closed.

The closing of the limit switch 75 causes the solenoid 97 to be energized since the limit switch portion 73b closed upon the wheel slide 11 reaching its retracted position. The activation of the solenoid 97 causes fluid to be supplied to the hydraulic cylinder 29 to pivot the first shield 26 counterclockwise about the hinge pin 31 from the position of FIG. 3 to the position of FIG. 4. When the first shield 26 pivots from the position of FIG. 3, the limit switch 89 opens.

Upon completion of counterclockwise pivoting of the first shield 26, the limit switch 72 is closed to cause energization of the solenoid 98. The activation of the solenoid 98 energizes the

rotary actuators

63 and 64 to cause the second shield 60 to be moved to its position between the workpiece 22 and the grinding wheel 14 as shown in FIG. 4.

As the second shield 60 starts to move, the limit switch 87 opens. When the second shield 60 completes its movement and is disposed between the workpiece 22 and the grinding wheel 14, the limit switch 74 is closed. The closing of the limit switch 74 causes energization of the solenoid 99 to retract the center of the footstock 24 so as to release the workpiece 22 therefrom. This enables the workpiece 22 to be removed from its supports (the headstock 23 and the footstock 24) and another of the workpieces 22 loaded.

The limit switch 85 opens as soon as the center of the footstock 24 starts to retract. Upon completion of retraction of the center of the footstock 24, the limit switch 71 is opened to drop the control relay 82.

The de-energization of the control relay 82 results in the normally open contacts 82-4 opening. As a result, the solenoids 97-99 are de-energized. However, no machine functions occur upon inactivation of the solenoids 97-99 because the hydraulic valves, which have the solenoids 97-99 connected thereto, are not shifted to their other functions when these solenoids are deenergized. Instead, the energization of the

solenoids

88, 86, and 84 are required to produce the opposite results to that produced by energization of the

solenoids

97, 98, and 99, respectively.

Another cycle would be started by again closing the cycle start push button 70 after unloading the ground workpiece and loading of another workpiece. The activation of the cycle stop push button 81, which stops the cycle, is utilized in an emergency.

To manually load and unload the workpieces 22, the coolant shield 49 must be pivoted so that the operator can reach into the grinding machine to remove the workpiece 22 from its supports and substitute another of the workpieces 22 therefor. Accordingly, when the coolant shield 49 is pivoted, the limit switch 77 is opened. This prevents actuation of the grinding cycle when the coolant shield 49 is not in its closed position.

When in he position of FIG. 3, the second shield 60 substantially reduces the amount of coolant being splashed out of the grinding area. It should be understood that the high rate of flow (100 gallons per minute) of the coolant through the chamber 34 and the opening 37 and the relatively high pressure (30 p.s.i.) produce a large amount of coolant.

Since it is necessary to occasionally replace the grinding wheel 14, access thereto must be provided. Accordingly, a door 101 is pivotally supported by hinges 102 on the rear wall 18 as shown in FIG. 2. This allows access to the grinding wheel 14 without requiring the grinding machine base to be too long.

Accordingly, the guard system of the present invention provides protection during manual loading an unloading from any fragment of the grinding wheel 14 if it should explode. Furthermore, the coolant may be supplied at a relatively high pressure and a relatively high flow rate to the grinding wheel 14.

When automatic loading and unloading of the workpieces 22 is employed rather than manual loading and unloading, the deflector 38, the coolant shield 49, and the second shield 60 are eliminated. Furthermore, it is necessary to reduce the height of the side wall so that the automatic loader may move the workpieces 22 over the top of the reduced height of the side wall 20.

With the elimination of the workpiece deflector 38 and the coolant shield 49, it is necessary to provide a shield 103, which is supported on the front base 10 as shown in FIG. 13, to protect the operator if the workpiece 22 is knocked loose from its supports (the headstock 23 and the footstock 24) by a fragment of the grinding wheel 14 if it explodes. Thus, the workpiece 22 would strike the shield 103 rather than the operator.

The operator protective shield 103, which is slidably mounted on a vertical wall 104 of the base 10 for horizontal movement to permit access to the workpiece 22 by the operator, includes an L-shaped member 105, which has end plates 106 (one shown) welded to each end thereof. It should be understood that the end plates 106 are cut out so as to not prevent horizontal sliding movement of the shield 103 relative to the vertical wall 104. The L-shaped member 105, which has its horizontal length extend for substantially the distance between the

side walls

19 and 20, is disposed to be struck by the workpiece 22 if the workpiece 22 is knocked loose from its supports by the grinding wheel 14 exploding.

The shield 103 also includes a member 107, which is spaced from the L-shaped member and is the same horizontal length as the member 105, having its opposite ends secured to the end plates 106. Strengthening ribs 108 are disposed between the adjacent spaced surfaces of the

member

105 and 107 to add strength to the member 105.

The member 107, which has the outer surface of its lower portion abutting against the inner surface of the vertical wall 104 of the base 10, functions as afurther protector for the operator if the L-shaped member 105 should buckle notwithstanding the ribs 108. Ribs 109,

which are secured to the outer surface of the member 107 and to a block 110, also aid in strengthening the member 107.

There, are three of the ribs 108 equally spaced from each other. There are an equal number of the ribs 109 with each of the ribs 109 aligned with one of the ribs 108.

The shield 103 is slidably mounted on the vertical wall 104 by having a plate 111, which extends for the same horizontal length as each of the

members

105 and 107, secured to the block 110, which is secured to the member 107 and extends for the same horizontal length as each of the

members

105 and 107, so that the shield 103 fits over the vertical wall 104. A pair of rollers 112 is rotatably supported by the plate 111 and slides on the upper surface of the vertical wall 104 of the base 10.

Accordingly, while the shield 103 is mounted between the

side walls

19 and 20 when protecting the operator, the shield 103 may be readily moved from this position by sliding along the vertical wall 104 through the rollers l 12. Thus, a removable safety shield is provided to protect the operator when there is automatic loading and unloading of the workpieces 22.

The upper end of the safety shield 103 may have a U- shaped splash guard 113, which is shown in phantom, supported thereon by clips 114. The U-shaped guard 1 13 opens toward the grinding machine so that the coolant is collected by the U-shaped splash guard 113 and directed through a passage, which is formed between the adjacent surfaces of the

members

105 and 107, for return to the coolant reservoir reservoit.

An advantage of this invention is that an easier handling of the workpiece may be accomplished than in previous guard systems. Another advantage of this invention is that the hinge pin for the shield, which receives the fragment of the exploding grinding wheel directly, is not subjected to any load to cause it to fail. A further advantage of this invention is that the grinding wheel coolant is utilized as an energy absorber. Still another advantage of this invention is that the coolant is directly applied to the interface between the grinding wheel and the workpiece so that the coolant nozzle does not have to be adjusted again due to wear of the grinding wheel.

For purposes of exemplification, particular embodiments of the invention have been shown and described according to the best present understanding thereof. However, it will be apparent that changes and modifications in the arrangement and construction of the parts thereof may be resorted to without departing from the spirit and scope of the invention.

What is claimed is:

1. ln a grinding machine having:

a base;

a wheel slide supported on said base for translational movement relative to a workpiece to be ground, said slide having a grinding wheel and a guard substantially enclosing said grinding wheel supported thereby;

means on said base to support the workpiece to be ground;

means cooperating with said grinding wheel and disposed above the workpiece in a grinding position during grinding of the workpiece by said grinding wheel to prevent any fragments of said grinding wheel in the event of a failure of said grinding wheel from escaping from between the top of the workpiece and said guard;

and means to move said cooperating means from the grinding position to a workpiece loading position toward said grinding wheel only when said grinding wheel is withdrawn from engagement with the workpiece by said slide for loading and unloading of workpieces.

2. The grinding machine according to claim 1 in which:

said cooperating means includes:

a shield movably supported by said base for movement between the grinding position and the workpiece loading position;

and means to limit the movement of said shield away from said grinding wheel in the event the grinding wheel fails and fragments of said grinding wheel strike said shield.

3. The grinding machine according to claim 2 in which said shield has energy absorbing means therein.

4. The grinding machine according to claim 3 in which said energy absorbing means comprises a liquid within said shield.

5. The grinding machine according to claim 3 in which:

said shield has means for the supply of a coolant to said grinding wheel;

and said energy absorbing means of said shield is the coolant flowing through said means in said shield.

6. In a grinding machine having:

a base;

means cooperating with said grinding wheel and disposed above the workpiece to prevent any fragments of said grinding wheel in the event of a failure of said grinding wheel from escaping from between the top of the workpiece and said guard;

means to move said cooperating means to a workpiece loading position toward said grinding wheel when said grinding wheel is withdrawn from engagement with the workpiece by said slide for loading and unloading of workpieces;

means movable between said cooperating means and the workpiece when said cooperating means is moved to its workpiece loading position;

and said movable means and said cooperating means cooperating to shield the operator from said grinding wheel during loading and unloading of the workpieces.

7. The grinding machine according to claim 6 in which:

said movable means comprises:

ashield; and means to support said shield for movement between a workpiece loading position and a grinding position.

8. The grinding machine according to claim 6 includ-' ing means to move said movable means to a position to prevent splashing of coolant from the machine during grinding of the workpiece by said grinding wheel.

9. The grinding machine according to claim 2 in which:

said shield includes:

a relatively thick metal plate forming the front wall of said shield; and sheet metal means secured to said plate and forming the side and back walls of said shield. 10. The grinding machine according to claim 9 in which:

said plate and said sheet metal means cooperate to form a coolant chamber therebetween for supply of a coolant to said grinding wheel; and means to introduce the coolant into said chamber, the coolant being an energy absorbing means. 11. The grinding machine according to claim 6 in which:

said cooperating means includes:

a shield movably supported by said base;

and means to limit the movement of said shield away from said grinding wheel in the event the grinding wheel fails and fragments of said grind-' ing wheel strike said shield;

said movable means is movable between said shield of said cooperating means and the workpiece when said shield of said cooperating means is moved to its workpiece loading position;

and said movable means cooperates with said shield of said cooperating means to shield the operator from said grinding wheel during loading and unloading of the workpieces.

12. The grinding machine according to claim 11 in which:

said movable means comprises:

a second shield; and means to support said second shield for movement between a workpiece loading position and a grinding position. 13. The grinding machine according to claim 11 in which:

said shield includes:

a relatively thick metal plate forming the front wall of said shield; and sheet metal means secured to said plate and forming the side and back walls of said shield; said plate and said sheet metal means cooperate to form a coolant chamber therebetween for supply of a coolant to said grinding wheel; and means to introduce the coolant into said chamber, the coolant being an energy absorbing means. 14. The grinding machine according to claim 13 in which:

! 1 said movable means comprises:

a second shield; and means to support said second shield for movement between a workpiece loading position and a grinding position.

15. The grinding machine according to claim 1 including:

workpiece deflecting means, separate from said cooperating means, supported by said base between the workpiece support position and the operator to prevent the workpiece from striking the operator if the workpiece is removed from its supports by fragments of said grinding wheel in the event of a failure of said grinding wheel.

16. The grinding machine according to claim 15 including means to removably support said workpiece deflecting means on said base.

* i I! t

Claims

1. In a grinding machine having: a base; a wheel slide supported on said base for translational movement relative to a workpiece to be ground, said slide having a grinding wheel and a guard substantially enclosing said grinding wheel supported thereby; means on said base to support the workpiece to be ground; means cooperating with said grinding wheel and disposed above the workpiece in a grinding position during grinding of the workpiece by said grinding wheel to prevent any fragments of said grinding wheel in the event of a failure of said grinding wheel from escaping from between the top of the workpiece and said guard; and means to move said cooperating means from the grinding position to a workpiece loading position toward said grinding wheel only when said grinding wheel is withdrawn from engagement with the workpiece by said slide for loading and unloading of workpieces.

2. The grinding machine according to claim 1 in which: said cooperating means includes: a shield movably supported by said base for movement between the grinding position and the workpiece loading position; and means to limit the movemEnt of said shield away from said grinding wheel in the event the grinding wheel fails and fragments of said grinding wheel strike said shield.

5. The grinding machine according to claim 3 in which: said shield has means for the supply of a coolant to said grinding wheel; and said energy absorbing means of said shield is the coolant flowing through said means in said shield.

6. In a grinding machine having: a base; a wheel slide supported on said base for translational movement relative to a workpiece to be ground, said slide having a grinding wheel and a guard substantially enclosing said grinding wheel supported thereby; means cooperating with said grinding wheel and disposed above the workpiece to prevent any fragments of said grinding wheel in the event of a failure of said grinding wheel from escaping from between the top of the workpiece and said guard; means to move said cooperating means to a workpiece loading position toward said grinding wheel when said grinding wheel is withdrawn from engagement with the workpiece by said slide for loading and unloading of workpieces; means movable between said cooperating means and the workpiece when said cooperating means is moved to its workpiece loading position; and said movable means and said cooperating means cooperating to shield the operator from said grinding wheel during loading and unloading of the workpieces.

7. The grinding machine according to claim 6 in which: said movable means comprises: a shield; and means to support said shield for movement between a workpiece loading position and a grinding position.

8. The grinding machine according to claim 6 including means to move said movable means to a position to prevent splashing of coolant from the machine during grinding of the workpiece by said grinding wheel.

9. The grinding machine according to claim 2 in which: said shield includes: a relatively thick metal plate forming the front wall of said shield; and sheet metal means secured to said plate and forming the side and back walls of said shield.

10. The grinding machine according to claim 9 in which: said plate and said sheet metal means cooperate to form a coolant chamber therebetween for supply of a coolant to said grinding wheel; and means to introduce the coolant into said chamber, the coolant being an energy absorbing means.

11. The grinding machine according to claim 6 in which: said cooperating means includes: a shield movably supported by said base; and means to limit the movement of said shield away from said grinding wheel in the event the grinding wheel fails and fragments of said grinding wheel strike said shield; said movable means is movable between said shield of said cooperating means and the workpiece when said shield of said cooperating means is moved to its workpiece loading position; and said movable means cooperates with said shield of said cooperating means to shield the operator from said grinding wheel during loading and unloading of the workpieces.

12. The grinding machine according to claim 11 in which: said movable means comprises: a second shield; and means to support said second shield for movement between a workpiece loading position and a grinding position.

13. The grinding machine according to claim 11 in which: said shield includes: a relatively thick metal plate forming the front wall of said shield; and sheet metal means secured to said plate and forming the side and back walls of said shield; said plate and said sheet metal means cooperate to form a coolant chamber therebetween for supply of a coolant to said grinding wheel; and means to introduce the coolant into said chamber, the coOlant being an energy absorbing means.

14. The grinding machine according to claim 13 in which: said movable means comprises: a second shield; and means to support said second shield for movement between a workpiece loading position and a grinding position.

15. The grinding machine according to claim 1 including: workpiece deflecting means, separate from said cooperating means, supported by said base between the workpiece support position and the operator to prevent the workpiece from striking the operator if the workpiece is removed from its supports by fragments of said grinding wheel in the event of a failure of said grinding wheel.