US3849940A

US3849940A - Honing machine

Info

Publication number: US3849940A
Application number: US00384758A
Authority: US
Inventors: T Yoshino; H Araki; S Nanba; N Fujimoto
Original assignee: Toyo Kogyo Co Ltd
Current assignee: Mazda Motor Corp
Priority date: 1972-08-11
Filing date: 1973-08-01
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26
Also published as: GB1385287A; DE2340598C3; DE2340598A1; IT992922B; DE2340598B2

Abstract

A honing machine having a honing stone movable radially inwardly and outwardly of a rotary shaft, in which constant pressure advance means and constant speed advance means are provided for feeding said honing stone radially outwardly of the rotary shaft and, in the honing operation, both of said means are actuated concurrently and one of them which is higher in advance rate is automatically selectively used for advancing the honing stone.

Description

United States Patent Yoshino et al.

[ 1 Nov. 26, 1974 HONING MACHINE Inventors: Tsutomu Yoshino, Hiroshima;

Shinichi Nanba, Hiroshima-ken; Norihiro Fujimoto, Hiroshima-ken; Hideo Araki, Hiroshima-ken, all of Japan Assignee: Toyo Kogyo Co., Ltd., Hiroshima-ken, Japan Filed: Aug 1, 1973 Appl. No.: 384,758

Foreign Application Priority Data Field of Search 51/34 R, 34 C, 34 D, 34 E, 51/34 F, 34 G, 34 H, 34 J, 34 K, 165.93, 346

[56] References Cited UNITED STATES PATENTS 2,345,581 4/1944 Caldwell 51/3 4 D 2,795,089 6/1957 Seborg 51/346 2,819,566 l/1958 Johnson 51/346 3,410,028 11/1968 Estabrook 51/34 C 3,466,809 9/1969 Estabrook 51/34 R Primary Examiner-Al Lawrence Smith Assistant ExaminerK. J. Ramsey Attorney, Agent, or Firm-Fleit, Gipple & Jacobson 5 7] ABSTRACT A honing machine having a honing stone movable radially inwardly and outwardly of a rotary shaft, in which constant pressure advance means and constant speed advance means are provided for feeding said honing stone radially outwardly of the rotary shaft and, in the honing operation, both of said means are actuated concurrently and one of them which is higher in advance rate is automatically selectively used for advancing the honing stone.

8 Claims, 15 Drawing Figures in I30 I :1 A B I V 3a 720 7'?) 72 6 5 PATENTE HUVZES I974 SHEET 3 OF 7 HONING MACHINE This invention relates to a honing machine having an improved advance device, and more specifically to such a honing machine which comprises constant pressure advance means and constant speed advance means for advancing a honing stone, both of said means being actuated concurrently and one of them which is faster in advance rate than the other being automatically selectively used for advancing the honing stone, whereby honing can be achieved efficiently with high accuracy.

A honing machine for honing the inner walls of annular workpieces is constructed such that a rotary grinding stone is advanced radially outwardly of the axis of rotation thereof to hone the inner walls of the workpiece into the desired dimensions. As a device for controlling the advance of the honing stone in conventional honing machines, a constant speed advance type and a constant pressure advance type have been known, but neither of them are entirely satisfactory. Namely, in the constant speed advance type the honing stone is advanced radially outwardly of the axis of rotation thereof at a constant rate by means of a screw or gear and the feeding rate of the honing stone per unit time is determined in consideration of a variation of the honing capacity of the honing stone due to filling of the grinding surface thereof in the honing operation and the strength of the honing stone. Since the honing stone is advanced at the constant rate even when the honing capacity has degraded during the honing operation due to filling of the grinding surface, there is the advantage that the abrasive particles filling the grinding surface of the honing stone drop off under the increased honing load and the honing stone restores its honing capacity (this effect will hereinafter be called a self-dressing effect), and thus a constant honing capacity can be maintained. On the other hand, however, since the honing stone is fed at the constant rate even in the period before the honing stone engages a workpiece or in the period from the time when the honing stone engages the workpiece to the time when the honing stone advance mechanism deforms elastically and the normal honing starts upon engagement of the honing stone with the workpiece, there is the disadvantage that a long time is wastefully taken in the initial stage of the honing operation and accordingly, the time required for the completion of honing becomes long.

In the constant pressure advance type, the honing stone is fed with a constant pressure by a pressure cylinder and the pressure for advancing the honing stone is determined in consideration of degradation of the honing capacity due to filling of the grinding surface of the honing stoneand the strength of the honing stone. Therefore, there is the advantage that the honing stone feeding rate can be increased in the initial stage of the honing operation and, when the pressure is set at a certain fixed value, the honing stone feeding rate can be changed according to the hardness of the workpiece.

However, this type has the disadvantage that the honing stone feeding rate decreases as the honing capacity degrades due to filling of the grinding surface of the honing stone.

An object of the present invention is to provide a honing machine which comprises constant pressure ad vance means and constant speed advance means for feeding a honing stone radially outwardly of the axis of rotation thereof, one of said means which is faster in advance rate than the other being automatically selectively used, so as to increase the efficiency of the honing operation by utilizing the advantageous features of both means.

Another object of the invention is to provide a honing machine of the character described, in which said constant pressure advance means and constant speed advance means are interconnected so that the switch ing of said means from one to another may be effected automatically and instantaneously for the selective use of said means.

Other advantages and features of the invention will become apparent from the following description when taken in conjunction with the accompanying drawings. In the drawings,

FIG. 1 is a graph showing the relationship between the feeding amount and time in a honing machine according to the invention;

FIG. 2 is a graph similar to FIG. 1, in another mode of operation of the honing machine; I

FIG. 3 is a sectional view showing a first embodiment of advance means of the honing machine according to the invention;

FIG. 4 is a sectional view taken on the line IV-lV of FIG. 3 and showing a driving mechanism for the honing stone expanding cone shown in FIG. 3;

FIG. 5 is a sectional view showing a modification of the feed screw driving portion shown in FIG. 3;

FIG. 6 is a sectional view showing a second embodiment of the advance means of the honing machine according to the invention;

FIG. 7 is a sectional view taken on the line VllVll of FIG. 6;

FIG. 8 is a sectional view showing a third embodiment of the advance means of the honing machine according to the invention;

FIG. 9 is a sectional view taken on the line IXIX of FIG. 8;

FIG. 10 is a sectional view showing a fourth embodiment of the advance means of the honing machine of the invention;

FIG. 11 is a view illustrating the hydraulic circuit shown in FIG. 10;

FIG. 12 is a sectional view showing a fifth embodiment of the advance means of the honing machine of the invention; and

FIGS. 13 15 are sectional views showing sixth to eighth embodiments of the advance means of the honing machine of the invention respectively.

Embodiments of the advance means of the honing machine according to the invention will be described hereunder with reference to the drawings.

With reference first to FIGS. 3 and 4, numeral 1 designates a main body of a honing machine and 2 designates a honing stone radially movably supported in a hollow rotary shaft 2a. The honing stone 2 is for honing the inner wall of an annular workpiece and rotationally driven by driving means meshing with external teeth 2b of the rotary shaft 2a. A wedge member 3 is axially movably disposed in the rotary shaft 2a and the honing stone 2 is moved radially outwardly or inwardly of the rotary shaft by said wedge member 3 when said wedge member moves rightwards or leftwards as viewed in FIG. 4. The amount of movement of the honing stone 2 corresponds to the amount of feed.

Numeral 4 designates a rod for driving the wedge member 3. One end of the rod 4 .is connected with a piston 6 of a constant pressure advance hydraulic cylinder and the other end thereof is located opposite to a head of a constant speed advance screw 7. The screw 7 is threadably extended through a cylindrical screw 10 having threads formed on both the inner and outer surfaces thereof and is driven at its rear end by a pinion 11. The pinion 11 is meshing with a rack 12 to be driven thereby. The screw 7 is caused to move by the cylindrical screw 10 when the pinion 11 is driven by the rack 12.

The cylindrical screw 10 is rotatably mounted in the main body 1 and meshing with threads formed on the inner surface of a worm wheel 14 which is in engagement with a worm l3 driven by a constant speed advance motor 19. The cylindrical screw 10 has an engaging groove 15 formed axially in the outer surface thereof and a pin 16 fixed to the main body 1 is received in said engaging groove 15 for holding said cylindrical screw 10 against rotation. Thus, it will be understood that, when the worm wheel 14 rotates, the cylindrical screw 10 moves axially while being held against rotation by the pin 16.

A pressurized oil is supplied to a port A of the hydraulic cylinder 5 through a directional control valve 17 to impart a predetermined honing load to the honing stone 2. The driving rod 4 is provided with a rack 4a which is in engagement with a pinion 9. When the pinion 9 is rotated by the driving rod 4, intermeshing

bevel gears

20, 21 rotate. The rotation of the bevel gear 21 is transmitted to a pinion 22 to rotate the same and the pinion'22 drives a rack 23 meshing therewith. The rack 23 causes the cone 3 to make a linear motion in the direction of the arrow L or L and thus the honing stone 2 is moved radially outwardly or inwardly of the rotary shaft.

Now, the operation of the honing stone advance means of the construction described above will be described. The honing stone 2 is inserted into the axial bore of an annular workpiece while rotating it together with the main body 2a by the driving means not shown through the gear 2b, and the main body 1 is reciprocated axially of the workpiece, with said honing stone 2 in engagement with the inner wall of said workpiece. The directional control valve 17 is shifted to a position 17A under control of control means 18 (FIG. 6) and pressurized oil is supplied to the right side of the piston 6 from the port A of the hydraulic cylinder 5 through said directional control valve. The constant speed advance motor 19 such as a pulse motor is concurrently set in motion by a signal from the control means 18 to drive the worm 13 at a constant speed to rotate the worm wheel 14. The worm wheel 14, when driven, moves the cylindrical screw 10 in the direction of the arrow K. In the event when the oil pressure of the constant pressure advance means and the screw feed amount of the constant speed advance means are set such that the gradient of a phantom curve b of the constant pressure advance may be greater than the gradient of the straight line a of the constant speed advance, the device operates as shown in FIG. 1. The honing stone 2 engages the workpiece at a point P to perform honing and the honing proceeds to a point 0,, with the rod being elastically deformed. During this period, the honing proceeds substantially along the phantom curve b as the cutting efficiency of the honing stone 2 is high.

The grinding surface of the honing stone 2 gradually becomes filled, with the honing capacity degrading, after passing the point 0,. The honing departs from the phantom curve b and proceeds along a curve c. During this period, the constant pressure advance is in effect since the rate of feed by the constant pressure advance means is higher than that by the constant speed advance means. The rod 4 moves faster than the cylindrical screw 10, but the pinion 11 is rotated by a force extremely smaller than the moving force of the rod 4, to move the screw 7 along the cylindrical screw 10, whereby the head of said screw 7 is held in light contact with the rear end of said rod 4.

When the honing proceeds further and reaches a pointQ where the honing capacity is further degraded due to filling of the grinding surface of the honing stone 2, the rate of feed per unit time by the constant pressure advance means becomes lower than that by the constant speed advance means, so that the cylindrical screw 10 moves causing the screw 7 to push the rod 4 and thus the constant speed advance comes in effect. Therefore, beyond the point Q the honing proceeds along a straight line a passing the point Q and parallel to a straight line a. However, when the honing load increases rapidly due to the constant speed advance and the honing stone 2 restores its honing capacity as a result of self-dressing, the constant pressure advance again comes in effect at a point Q and thereafter, honing proceeds along a curve e to a point Q, where the rate of feed by the constant speed advance means is greater than that by the constant pressure advance means, with the grinding surface of the honing stone 2 being gradually filled. Between the point 0, and a point Q honing proceeds along a straight line f parallel to the straight line a with the constant speed advance means in effect, and from the point Q honing proceeds along a curve g with the constant pressure advance means in effect. The above-described operation is repeated and finally the honing is completed at a point R. Therefore, the time T required for the completion of honing is much shorter than that in the case when the constant speed advance means only is used.

In the event when the honing machine of the invention is set such that the gradient of the phantom curve b representing honing with the constant pressure advance means may be of a value smaller than that of the gradient of the straight line a representing honing with the constant speed advance means, the honing proceeds as shown in FIG. 2, and such condition occurs when the set oil pressure for the constant pressure advance means is low or the hardness of the workpiece is large.

In FIG. 2, the honing stone 2 engages the workpiece at a point P. In the initial stage of honing, the rod 4 deforms elastically and the honing load is small and the honing capacity of the honing stone is large. Therefore, up to a point Q, the rate of feed by the constant pressure advance means is greater than that by the constant speed advance means and honing proceeds substantially along a phantom curve b. When the honing reaches the point Q where the honing load reaches a constant value, the rate of feed by the constant speed advance means becomes greater than that by the constant pressure advance means, so that thereafter, honing proceeds along a straight line d parallel to a straight line a up to a point R where the honing is completed. In this case, the gradient of the phantom curve b is smaller than that of the straight line a representing honing with the constant speed advance means, so that the advance means will not be changed from the constant speed advance means to the constant pressure advance means beyond the point Q Therefore, the honing pro ceeds along P Q R in FIG. 2 and the honing time t is shorter than the tie t required for honing with only the constant speed advance means, similar to the preceding case.

When the inner wall of the annular workpiece has been honed in the desired dimension accurately, the directional control valve 17 is shifted to a position 178 to supply the oil pressure to a port B of the hydraulic cylinder. Further, the constant speed advance motor 19 and the pinion 11 are driven reversely to move the cylindrical screw and the screw 7 in the direction of the arrow K, so as to return the rod 4 and the honing stone 2 to their original positions.

FIG. 5 shows an embodiment in which a windmill driven by pressurized air supplied from an

air supply port

24 or 24a is used, instead of the pinion Ill in the embodiment of FIG. 2, for driving the screw 7.

Hereunder, the second through eighth embodiments will be described. In these embodiment, similar parts are indicated by same reference numerals and the de scriptions thereof are omitted. These embodiments of the honing machine of the invention have the same honing characteristic as shown in FIGS. 1 or 2, and a detailed description of the honing characteristic will not be given.

In the embodiment shown in FIGS. 6 and 7, a cone or wedge member 3 for expanding the honing stone 2 is connected with a rod 4 which in turn is connected to a piston rod of a hydraulic cylinder 5 through a rotatable joint 26. A rotary shaft 2a is rotationally driven together with the cone 3 by driven means not shown. The piston rod 30 is rotatably connected to a worm shaft 32 by a joint 32a. This worm shaft 32 is driven by a driving force transmitted thereto from a constant speed advance worm 13a through a one-way clutch 31. Namely, the one-way clutch 31 is comprised of an outer wheel 34 engaging a worm 33 which is rotatable integrally with a worm wheel 14a meshing with a worm 13a, an inner wheel 37 having a pinion meshing with the worm shaft 32, and a roller 38 engageable with the inner and

outer wheels

37, 38 in one way only.

This one-way clutch 31 makes an idling rotation when the outer wheel 34 rotates counterclockwise and performs a clutching action when the same rotates clockwise, and makes an idling rotation when the inner wheel 37 rotates clockwise and performs a clutching action when the same rotates counterclockwise, as viewed in FIG. 6.

The worm shaft 32 is provided thereon with a oneway clutch 43 which is comprised of an inner wheel 40 rotatably mounted on said shaft 32 and an outer wheel 42 adapted to engage said inner wheel 40 in one-way through a roller 40, said outer wheel 42 being in meshing engagement with a rack 44 which operates when the cone 3 is to be contracted.

Further, a clutch member 45 is axially slidably mounted on the rear end portion of the worm shaft 32. This clutch member 45 rotates integrally with the worm shaft 32 when a key 46 provided on the inner surface of said clutch member 45 engages in a key groove 49 formed in the worm shaft 32. The clutch member 45 and the inner wheel 40 are provided at the confronting portions thereof with interengageable teeth 47, 47a. The rotation of the inner wheel 40 is transmitted to the worm shaft 34 through the clutch member 45 when the teeth 47, 47a are in engagement with each other. On the other hand, when the teeth 47', 47a are disengaged by pulling the clutch member 45 in the direction of the arrow M, the worm shaft 32 is disengaged from the inner wheel 40 and can be rotated manually by rotating the clutch member 45. In this case, therefore, the zone 3 can be moved manually.

In the operation, pressurized oil to impart a honing load to the honing stone is supplied to a port A of the hydraulic cylinder 5 under control of control means 18 and the constant speed advance motor 19 is set in motion, similar to the preceding embodiment.

In a condition, such as in the initial stage of honing, wherein the rate of feed by the constant pressure advance means is greater than that by the constant speed advance means, the worm shaft 32 moves, under the effect of the hydraulic cylinder 5, at a speed faster than the speed of rotation of the outer wheel 34 of the oneway clutch 31 caused by the constant speed advance means, and the inner wheel 37 makes a clockwise idling rotation.

In a condition wherein the rate of feed by the constant pressure advance means becomes smaller than that by the constant speed advance means due to filling of the grinding surface of the honing stone or for other reasons, the speed of rotation of the outer wheel 34 caused by the rotation of the worm 33 incident to the rotation of the worm 13a becomes higher than the speed of rotation of the inner wheel 37 caused by the hydraulic cylinder 5 and the one-way clutch 3I acts, so that the constant speed advance comes in effect to drive the cone 3. Thus, honing proceeds along the thick line curve shown in FIGS. I or 2.

The rack 44 during the honing operation is held in its rightward position by supplying the oil pressure from a port C (FIG. 7). The one-way clutch 43 makes an idling rotation when the rack 44 is shifted to the rightward position. Upon completion of honing of the annular workpiece accurately in the desired dimension, the pressurized oil is supplied to a port B of the hydraulic cylinder 5 and further, the rack 44 is returned to its original position by rotating the worm 13a reversely, to return the worm shaft 32 and the honing stone 2 to their original positions.

In this returning operation, the pressurized oil is supplied from a port D shown in FIG. 7 to retreat the rack 44 and bring the one-way clutch 43 into the engaged position. The movement of the rack 44 causes rotation of the outer wheel 42 and the rotation of said outer wheel is transmitted to the worm shaft 32 through the clutch member 45 to return said worm to its original position. The final position of the worm shaft 32 is determined by the length of stroke of the rack 44 which is previously adjusted by means of a set screw 48.

This embodiment is simpler in construction than the first embodiment as the constant pressure advance means and constant speed advance means are interconnected through the one-way clutch.

In the embodiment of FIG. 8, a pinion 9 meshing with a rack 40 of a cone driving rod 4 is connected in the same manner as shown in FIG. 4. One end of the rod 4 is connected through a thrust bearing 54 to one end of a male screw 53 which constitutes a ball screw 52 by engagement with a female screw 51 through a number of balls 50 arranged along the screw.

The female screw 51, together with an outer wheel 14b having a gear formed on the outer periphery thereof, constitutes a one-way'clutch 56 with balls 55 interposed therebetween as shown in FIG. 9. This oneway clutch makes an idling rotation when the outer wheel 14b rotates counterclockwise and performs a clutching action when the same rotates clockwise, and make an idling rotation when the female screw 51 rotates clockwise and performs a clutching action when the same rotates counterclockwise, as will be understood from FIG. 9. The outer wheel 14b is in meshing engagement with a worm 13b which is driven from a constant speed advance motor 19 consisting of a hydraulic motor or pulse motor. A pinion 57 is axially slidably mounted on the rear end portion of the male screw 53 and engaged with a rack 58 which is operated when the honing stoke is to be contracted.

This rack 58 corresponds to the rack 44 shown in FIG. 7 and defines the return position of the male screw 53 by being operated by a hydraulic cylinder not shown, similar to the embodiment of FIG. 7. Numerals 59a, 59b respectively designate limit switches to define both ends of the stroke of the male screw 53 to determine the range of use (the total amount of wear) of the honing stone.

In the honing operation, the pressurized oil is supplied to the port A of the hydraulic cylinder under control of the control means 18, and the constant speed advance motor 19 is set in motion concurrently. In the event when the rate of feed by the constant pressure advance means operating under effect of the hydraulic cylinder 5 is greater than that by the constant speed advance means operating under effect of the constant speed advance motor 19, the rod 4 is advanced with a constant pressure by the oil pressure of the hydraulic cylinder 5 and the male screw 53 proceeds while being pulled by the rod 4 and without rotating. In this case, the inner wheel of the one-way clutch 56 or the female screw 51 makes an idling rotation.

On the other hand, when the rate of feed by the hydraulic cylinder 5 becomes lower than that by the constant speed advance motor 19 due to filling of the grinding surface of the honing stone or for other reasons, the speed of rotation of the outer wheel 14b driven by the worm 1312 becomes higher than the speed of rotation of the female screw 51 driven by the male screw 53, so that the one-way clutch 56 is placed in the clutching position and the driving force of said outer wheel 14b is transmitted to the ball screw 52, with the result that the rod 4 moves at a constant speed and a constant speed advance honing is performed.

In the manner described, either one of the constant pressure advance means and constant speed advance means is selected automatically and honing is carried out along the line P Q R shown in FIGS. 1 or 2. Upon completion of the honing, the directional control valve 17 is shifted to the position 17B under control of the control means 18 to operate the hydraulic cylinder 5 in the returning direction, and the worm 13b is rotated reversely. Further, the rack 58 is moved to return the honing stone to the original position. The return position of the male screw 53 is defined by defining the return position of the rack 58 as stated previously. This embodiment has the advantage that the operation is smooth since the ball screw is used as constant speed advance means.

The embodiment shown in FIG. 10 is similar to the third embodirnent described above and in which similar parts are indicated by same reference numerals, and their descriptions will be omitted.

An outer wheel 14b of a one-way clutch 56 is pro vided on the outer surface with a gear which is meshing with a pionion 61. A shaft 60 is concentrically rotatably extended through a worm wheel 62 which is rotatably mounted in a main body 1 and meshing with a worm 13b. The rotation of the worm wheel 62 is transmitted to the pinion 61 through a magnetic clutch 63.

In this embodiment, a driving rod 4 is formed integrally with a male screw 53 of a ball screw 52. A key 64 is provided at the rear end portion of the main body I, which is engaged in a guide groove 65 formed axially in the male screw 53 to hold said male screw 53 against rotation.

A constant capacity contraction cylinder means 66 (see FIG. 11) is provided at a port A ofa hydraulic cylinder 5 for defining the return position of the driving rod 4 when the honing stone is contracted. The amount of movement of the rod in the return movement from its honing ending position is set by a set screw 67.

FIG. 11 is a hydraulic circuit diagram showing the re lation between the hydraulic cylinder 5 and the contraction cylinder means 66.

As shown, an output port E of the contraction cylinder means 66 is connected to the port A of the hydraulic cylinder 5. The contraction cylinder means 66 has ports F, G communicating with oil pressure chambers 'SF, SG formed on both sides of piston 68 disposed therein, and pressurized oil is supplied from an oil pump (not shown) to the port G through a check valve 69 and to the port F through the check valve 69 and a directional control valve 17. The pressure receiving areas of the chambers SF, SG and a chamber SE are se lected to be in the relation of SF SG SE.

This embodiment operates in the following manner: Namely, the directional control valve 17 is shifted to a position 17A to supply pressurized oil to the right side of the cylinder 5 from the port a, and a worm 13b is driven by a constant speed advance motor 19, with the magnetic clutch 63 being closed to rotate a worm wheel 62.

When the rate of feed of the rod 4 by the hydraulic cylinder 5 is greater than the rate of feed of the male screw 53 by the constant speed advance motor 19, the male screw 53 moves by being pulled by the piston 6 and the clutch 56 is making an idling rotation. On the other hand, when the rate of feed of the rod 4 by the hydraulic cylinder 5 reduces due to filling of the grinding surface of the honing stone or for other reasons and the rate of feed by the constant speed advance motor 19 becomes greater than that by the hydraulic cylinder 5, the one-way clutch 56 performs the clutching action and the rod 4 is fed forcibly according to the rotation of the constant speed advance motor 19.

Thus, honing carried out along the line P Q a R shown in FIGS. 1 or 2.

Concurrently with the start of honing, the pressurized oil is supplied to the ports E, G of the contraction cylinder means 66 to elevate the piston 68 by taking advantage of the pressure receiving area difference.

Upon completion of the honing, the magnetic clutch 63 is opened and the directional control valve 17 is shifted to its neutral position 17C to supply the pressurized oil to the hydraulic cylinder from the port B and thereby to return the rod 4 to its original position.

In this case, the piston 68 of the contraction cylinder means 66 is lowered to the position defined by the set screw 67 under the effect of the pressuried oil fed back from the port A of the hydraulic cylinder 5 and acting in the port E, and the pressurized oil supplied to the port F from the directional control valve 17.

The amount of return movement of the piston 6 of the hydraulic cylinder 5 is determined by the amount of oil flowing into the chamber SA of the contraction cylinder means 66, and the return position of the rod 4 or the return position of the honing stone is determined by the amount of downward movement of the piston 68. Thus, the rod 4 can be returned a predetermined stroke, regardless of the amount of wear of the honing stone resulting from the honing operation.

This embodiment has the advantage that the honing can be achieved smoothly with high accuracy, since the ball screw is used as constant speed advance means.

The embodiment of FIG. 12 is the combination of the embodiments of FIGS. 6 and 10, to which further improvements are made.

A rod 71 for driving cone 3 for expanding thehoning stone 2 and a rod 72 connected with a piston 6 of a hydraulic cylinder 5 are arranged parallel to each other, and racks 71a, 72a are provided at the confronting portions of said

rods

71, 72. A pinion 73 is interposed between the

rods

71, 72, in meshing engagement with the two racks 71a, 72a. An arrangement is made such that the pinion 73 is driven from a constant speed advance motor 19 through a one-way clutch 31a. Namely, the

one-way clutch 31a is comprised of an outer wheel which is meshing with a worm 33 connected to and driven by a worm wheel 14a, meshing with a worm 13a, through a magnetic clutch 63, an inner wheel 37 which is integral with the pinion 73, and a roller 38 which is interposed between said outer and

inner wheels

34, 37. This one-way clutch makes an idling rotation when the outer wheel 34 rotates clockwise and performs the clutching action when the same rotates counterclockwise, and makes an idling rotation when the inner wheel 37 rotates counterclockwise and performs the clutching action when the same rotates clockwise, as viewed in FIG. 12. Numeral 74 designates a frictional element to impart to the outer wheel 34 of the one'way clutch 31a a frictional load larger than the friction occurring at the idling rotation of the one-way clutch 31a, and thereby to displace a clearance between the engaging portions of the rack 71a and pinion 73 in one way. Contraction cylinder means 66 which performs the same function as that shown in FIG. 11 is connected to a port A of a hydraulic cylinder 5.

Now, the operation of this embodiment will be described. A directional control valve 17 is shifted to a position 17A to supply pressurized oil to the left side of the cylinder 5 from the port A to move the rod 72 rightwards. The pinion 73 meshing with the rack 72a is rotated counter-clockwise to advance the rod 71 through the rack 71a. Concurrently, the magnetic clutch 63 is closed to drive the outer wheel 34 by the constant speed advance motor 19 therethrough. Namely, the outer wheel is rotated counterclockwise as viewed in FIG. 12.

When the rotating speed of the pinion 73 driven by the cylinder 5 is higher than the rotating speed of the iii) outer wheel 34 driven by the constant speed advance motor 19, the one-way clutch 31a makes an idling rotation and the constant pressure advance means comes in effect for feeding the honing stone. On the other hand, when the rotating speed of the pinion 73 decreases due to filling of the grinding surface of the honing stone or for other reasons and becomes lower than the rotating speed of the outer wheel 34, the one-way clutch 31a performs the clutching action to cause the pinion 73 to rotate counterclockwise. Thus, honing is carried out along the line P Q R shown in FIGS. 1 or 2.

In this embodiment, however, the constant pressure advance and constant speed advance are effected by the rotation in the same direction of the single pinion 73 meshing with the rack 71a of the cone operating rod 71, and a frictional resistance which is larger than the friction at the idling rotation of the one-way clutch 31a is imparted to the outer wheel 34,. so that the teeth of the rack 71a and pinion 73 interengage always on the same side throughout the honing operation. This is highly advantageous in eliminating a delay in changing the mode of advance, e.g., from constant pressure advance to constant speed advance, otherwise occurring due to a back lash of the interengaging teeth of the rack 71a and pinion 73, and in achieving the change efficiently. It is to be understood that the frictional element may be provided on the shaft of the worm 33 instead of the outer wheel 34 of the one-way clutch 31a. In this case, the change of the advance mode is subjected to the influence of a back-lash between the worm 33 and outer wheel 34, but the effect of the arrangement in eliminating the time delay is reduced only slightly. It will be understood, therefore, that the number of intermeshing parts, such as gears and wonns, interposed between the frictional element and the oneway clutch should be reduced to minimum.

The embodiment of FIG. 13 is the combination of the embodiments of FIGS. 3 and 8.

In this embodiment, a cone operating rod 4 is slidably extended through a cylindrical screw 10a meshing with a constant speed advance screw 14 and through a clutch box formed at the rear end portion of said cylindrical screw 10a integrally therewith. The clutch box 80 is slidably received in a recess 1a formed in a main body 1 of the honing machine. A clutch opening and closing cylinder 81 is disposed in the rear portion of the clutch box and a cylindrical piston 82 is slidably disposed in said cylinder 81. The rod 4 is loosely extended through the cylindrical piston 82. Pins 83 are fixed on the rod 4 forwardly of the piston 82. The clutch box 80 has formed therein a chamber 84 which is expanding forwardly of the pins 83 and rollers 86 are disposed in said chamber. These rollers 86 are urged toward the pins 83 by a spring 85 and, together with said pins, con stitute a one-way clutch to connect or disconnect the rod 4 and the clutch box 80. Namely, the rod 4 and clutch box 80 are connected and. operated integrally when the rollers 86 are engaged in between said rod and clutch box under the biasing force of the spring 85, whereas they are released from iinterengagement and operable individually when the piston 82 and therefore the pins 83 are moved leftwards as viewed in FIG. 13 to move the rollers 86 off the clutching position. On the outer surface of the screw 14 meshing with the cylindrical screw 10a provided forwardly of the clutch box 90 is provided a gear which is meshing with a worm l3 I driven from a constant speed advance motor 19 such as a hydraulic motor or pulse motor.

For regulating the return position of the rod 4, the contraction cylinder means 66 described with reference to FIG. 11 is communicated with the hydraulic cylinder 5.

The operation of this embodiment will be described hereunder: The directional control valve 17 is shifted to a position 17A under control of the control means 18 to supply pressurized oil to the right side of the cylinder from the port A and the constant speed advance motor 19 is set in motion.

When the rate of advance by the hydraulic cylinder 5 is greater than the rate of advance by the constant speed advance motor 19, the rod 4 is advanced by the operation of the hydraulic cylinder 5, and the rollers 86 of the one-way clutch are not in the clutching position.

On the other hand, when the rate of advance by the hydraulic cylinder 5 decreases due to filling of the grinding surface of the honing stone or for other reasons, and becomes lower than the rate of advance by the constant speed advance motor 19, the rollers 86 of the one-way clutch are automatically shifted into the clutching position, so that the rod 4 is advanced at a constant speed integrally with the cylindrical screw a by the driving force of the constant speed advance motor 19.

Thus, the constant pressure advance means or constant speed advance means is automatically selected and the honing is carried out along the line P Q R as shown in FIGS. 1 or 2.

Upn completion of the honing, the constant speed advance motor 19 is stopped under control of the control means 18 and concurrently, the pressurize-oil is supplied to a right side chamber 81a of the clutch opening and closing cylinder 81 to cause the piston 82 to move leftwards as viewed in FIG. 13. The leftward movement of the piston 82 causes through the pins 83 the rollers 86 to move out of the clutching position, whereby the rod 4 is released from engagement with the clutch box 80. Thereafter, the directional control valve 17 is shifted to its neutral position, whereby the rod is moved in the direction the arrow K by the piston 6 of the hydraulic cylinder 5, and thus, the honing stone is returned to the original position which is defined by the contraction cylinder means 66.

The engaging position of the cylindrical screw 10a is displaced forwardly by the constant speed advance motor 19 very slightly on each honing operation. Therefore, the cylindrical screw 10a, after use of the honing machine, is returned to a suitable position by rotating the motor 19 reversely upon disengaging the clutch box 80 and rod 4 by the clutch opening and closing cylinder 81.

Now, in the embodiment of FIG. 14, numeral 4 designates a cone operating rod of the same construction as the rod shown in FIG. 3, which is meshing with a pinion 9 at a rack 4a formed thereon. Formed integrally at the rear end of the rod 4 is a constant pressure advance hydraulic cylinder 90 which is slidably received in a recess 1a formed in a main body 1 of the honing machine. In the cylinder 90 is slidably disposed a piston 92, and a piston rod 93 connected with said piston 92 is slidably inserted in the axial bore 91 of a sleeve portion 90a of the rod 4. Slits 94 are formed longitudinally in the front portion of the sleeve portion 90a and a pin 95 fixed to and extending through the piston rod 93 is slidably received in said slits 94 to project outwardly of the rod 4. The projecting ends of thepin 95 are fixed to a cylindrical screw 10b slidably mounted on the rod 4 so that the cylindrical screw 10b and the piston rod 93 may be movable integrally. The cylindrical screw 10b is in meshing engagement with a constant speed advance screw 14 which is formed on the outer surface thereof with a gear which is meshing with a worm l3 driven by a constant speed advance motor 19 such as a hydraulic motor or pulse motor. The cylinder is provided with a port A for supplying pressurized oil to the left side of the piston 92 and a port B for sypplying pressurized oil to the right side of the piston 92. Further, the contraction cylinder means 66 described in the preceding embodiments is provided in communication with the port A. Numeral 96 designates a check valve interposed between an oil pump (not shown) and a directional control valve 17 to prevent reverse flow of the pressurized oil from the oil pump.

This embodiment operates in the following manner: Namely, the directional control valve 17 is shifted to a position 17A under control of control means 18 to supply pressurized oil to the port A of the cylinder 90, and concurrently the worm 13 is rotated by actuating the constant speed advance motor-19.

When the constant pressure advance rate is greater than the constant speed advance rate, the speed of the constant pressure advance cylinder 90 moved by the pressurized oil supplied to the left side chamber 97 of said cylinder becomes higher than the speed of the cylindrical screw 10b moved forward by the constant speed advance screw 14 in engagement therewith and, therefore, the speed of the piston rod 93 connected integrally to said screw 14 by the pin 95, and the rod 4 moves forward at a higher speed in the cylindrical screw 10b. In this case, the pin connecting the piston rod 93 with the cylindrical screw 10b moves in the slits 94 relative thereto. Thus, the constant pressure advance works effectively.

On the other hand, when the constant pressure advance rate is smaller than that of the constant speed advance rate due to filling of the grinding surface'of the honing stone or for other reasons, the forward moving force added to the piston rod 93 is larger than that added to the cylinder 90. But, since the pressurized oil in the chamber 97 of the cylinder 90 is sealed therein by the check valve 96, the forward moving force of the piston rod 93 is transmitted to the cylinder 90 and the cylinder 90 moves at the constant speed advance speed by the piston rod 93.

Thus, the constant speed advance works effectively.

The constant pressure advance means or constant speed advance means is automatically selected in the manner described and the honing is carried out along the line P Q, R shown in FIGS. 1 or 2.

The embodiment shown in FIG. 15 is a modification of the embodiment of FIG. 14.

In this embodiment, a cone operating rod 4 is directly connected with a piston rod 93 of a constant pressure advance hydraulic cylinder 90 to be operated integrally therewith and a cylindrical screw 10b which moves forward in engagement with a constant speed advance screw 14 is formed at the forward end of the cylinder 90 integrally therewith. In the operation, pressurized oil is supplied to a right side chamber 98 of the cylinder 90 and the constant speed advance worm 13 is driven from a motor 19. A piston rod 93 moves forward at a faster speed than the cylinder 90 and constant pressure advance takes place while the honing capacity is high as at the start of honing. On the other hand, when the honing capacity reduces, the forward moving force added to the cylinder 90 is larger than that added to the piston rod 93. But, since the pressurized oil in the chamber 98 of the cylinder 90 is sealed therein by the check valve 96, the forward moving force of the cylinder 90 is transmitted to the piston rod 93 and the piston rod 93 moves at the constant speed advance speed by the cylinder 90. Thus the constant speed advance takes place.

Thus, in this embodiment also, the honing is carried out along the line P Q, R shown in FIGS. 1 or 2.

The embodiments of FIGS. 14; and 15 have the advantage that the construction is simple, because the driving shaft of the constant speed advance system and the driving shaft of the constant pressure advance system are operatively interconnected by the constant pressure advance piston or cylinder and a speed difference occurring between the two system during the honing operation can be absorbed by a very simple construction.

What is claimed is:

1. A honing machine comprising a honing stone supported for rotation with a rotary shaft, means for rotating said honing stone, advance means for feeding said honing stone radially outwardly of said rotary shaft, and said advance means including a combination of a constant pressure advance mechanism and a constant speed advance mechanism and selecting means for automatically selecting one of said two mechanisms which is faster in advance speed than the other for feeding the honing stone.

2. A honing machine as claimed in claim 1, wherein said advance means further includes a feed member for feeding said honing stone radially outwardly of said roll ll said constant pressure advance mechanism consists of fluid cylinder means and said fluid cylinder means is provided with returning fluid cylinder means for returning said fluid cylinder means a predetermined amount by withdrawing a predetermined volume of pressurized fluid from the pressure side thereof.

5. A honing machine as claimed in claim 2, wherein said advance mechanism further includes a first rack member operatively connected with said feed member,

tary shaft, said constant pressure advance mechanism includes fluid cylinder means for transmitting a constant pressure driving force to said feed member, said" constant speed advance mechanism includes mechanical driving means for transmitting a constant speed driving force to said feed member, and said selecting means includes connecting means for transmitting said constant speed driving force from said mechanical driving means only toward said feed member.

3. A honing machine as claimed in claim 2, wherein said fluid cylinder means has a piston rod which is operatively connected with said feed member, said mechanical driving means has a driven member rotationally driven at a constant speed and said connecting means operatively connects said driven member with the piston rod of said fluid cylinder means and includes a one way clutch for transmitting the driving force from said driven member only towards said piston rod.

4. A honing machine according to claim I, wherein a pinion meshing with said first rack member, and a second rack member meshing with said pinion, said fluid cylinder means is connected with said second rack member, said mechanical driving means has a driven member rotationally driven at a constant speed and said connecting means includes a. one-way clutch for transmitting the rotational force of said driven member to said pinion.

6. A honing machine according to claim 5, wherein frictional means is provided which contacts said driven member with a frictional force larger than that of said one-way clutch when said one-way clutch is making an idling rotation.

7. A honing machine as claimed in claiml, wherein said advance means comprises a feed member for feeding said honing stone radially outwardly of said rotary shaft, an axially movable shaft operatively connected with said feed member for effecting feeding operation of the feed member when axially moved, and said constant pressure advance mechanism comprises fluid operated piston-cylinder means having a cylinder and a piston received by said cylinder for reciprocating movement therein, one of the cylinder and the piston being movable as a unit with said axially movable shaft and the other being combined with said constant speed advance mechanism and means for supplying a constant fluid pressure to said cylinder for driving said axially movable shaft to operate the feed member.

8. A honing machine as claimed] in claim 1, wherein said advance means comprises a feed member for feeding said honing stone radially outwardly of said rotary shaft, a driving member operatively connected with said feed member, said constant pressure advance mechanism including fluid cylinder means having a piston connected with said driving member, said constant speed advance mechanism including a female screw member rotationally driven at a constant speed, a male screw member meshing with said female screw mem ber, means for unrotatably and axially movably sup porting said male screw member, a. driven member supported on said male screw member in such a manner as to be movable together with said male screw member and means for holding said driven member constantly in contact with the free end of said driving member, said driving member being operated by said fluid cylinder means or said male screw member whichever is faster in operating speed thereby to feed the honing stone radially outwardly of the rotary shaft through said feed member.

Claims

2. A honing machine as claimed in claim 1, wherein said advance means further includes a feed member for feeding said honing stone radially outwardly of said rotary shaft, said constant pressure advance mechanism includes fluid cylinder means for transmitting a constant pressure driving force to said feed member, said constant speed advance mechanism includes mechanical driving means for transmitting a constant speed driving force to said feed member, and said selecting means includes connecting means for transmitting said constant speed driving force from said mechanical driving means only toward said feed member.

3. A honing machine as claimed in claim 2, wherein said fluid cylinder means has a piston rod which is operatively connected with said feed member, said mechanical driving means has a driven member rotationally driven at a constant speed and said connecting means operatively connects said driven member with the piston rod of said fluid cylinder means and includes a one-way clutch for transmitting the driving force from said driven member only towards said piston rod.

4. A honing machine according to claim 1, wherein said constant pressure advance mechanism consists of fluid cylinder means and said fluid cylinder means is provided with returning fluid cylinder means for returning said fluid cylinder means a predetermined amount by withdrawing a predetermined volume of pressurized fluid from the pressure side thereof.

5. A honing machine as claimed in claim 2, wherein said advance mechanism further includes a first rack member operatively connected with said feed member, a pinion meshing with said first rack member, and a second rack member meshing with said pinion, said fluid cylinder means is connected with said second rack member, said mechanical driving means has a driven member rotationally driven at a constant speed and said connecting means includes a one-way clutch for transmitting the rotational force of said driven member to said pinion.

7. A honing machine as claimed in claim 1, wherein said advance means comprises a feed member for feeding said honing stone radially outwardly of said rotary shaft, an axially movable shaft operatively connected with said feed member for effecting feeding operation of the feed member when axially moved, and said constant pressure advance mechanism comprises fluid operated piston-cylinder means having a cylinder and a piston received by said cylinder for reciprocating movement therein, one of the cylinder and the piston being movable as a unit with said axially movable shaft and the other being combined with said constant speed advance mechanism and means for supplying a constant fluid pressure to said cylinder for driving said axially movable shaft to operate the feed member.

8. A honing machine as claimed in claim 1, wherein said advance means comprises a feed member for feeding said hOning stone radially outwardly of said rotary shaft, a driving member operatively connected with said feed member, said constant pressure advance mechanism including fluid cylinder means having a piston connected with said driving member, said constant speed advance mechanism including a female screw member rotationally driven at a constant speed, a male screw member meshing with said female screw member, means for unrotatably and axially movably supporting said male screw member, a driven member supported on said male screw member in such a manner as to be movable together with said male screw member and means for holding said driven member constantly in contact with the free end of said driving member, said driving member being operated by said fluid cylinder means or said male screw member whichever is faster in operating speed thereby to feed the honing stone radially outwardly of the rotary shaft through said feed member.