US3897660A

US3897660A - Apparatus for automatically removing fins of castings

Info

Publication number: US3897660A
Application number: US504930A
Authority: US
Inventors: Kenji Chijiiwa; Katsuo Shirahige
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-09-17
Filing date: 1974-09-11
Publication date: 1975-08-05
Anticipated expiration: 1992-08-05
Also published as: FR2243783B1; DE2443829A1; DE2443829B2; DE2443829C3; GB1433709A; FR2243783A1; JPS5316949B2; JPS5055536A

Abstract

An apparatus for automatically removing fins of castings wherein respective air springs are provided to resist a component in the normal direction and a component in the tangential direction with respect to the hone grinding surface of the contact surface of a hone and work of the grinding resistance applied to the grindinghone and are made to be fed with air pressures set in response to the size, thickness and the material of the fin of the work and a motor to control the work in the direction of the component in the normal direction and a motor to control it in the direction of the component in the tangential direction by converting the displacements of the above mentioned air springs to electric signals with two differential transformers are provided.

Description

United States Patent Chunwa et al.

1 APPARATUS FOR AUTOMATICALLY REMOVING FINS OF CASTINGS [75l inventors: Kenji Chijiiwa; Katsun Shirahige,

both of Chiba, Japan I73] Assigncc: Kenji Chijiiwa, Chiba Japan [22] Filed: Sept. 11, 1974 [211 Appl, No: 504,930

[311] Foreign Application Priority Data Sept 17 1973 Japan 48-10467] [52] US. Cl 1. 511165.77; 51/161592 [51I Int. Cl .7 B24b 49/16 [SKI Field of Search 51/165 R. 165.77, 16592 {56] References Cited UNITED STATES PATENTS 3.274.738 9/1966 Kuniholm 51/165 R 3,672,100 6/1972 Pesante 51/165]? Aug. s, 1975 I 57] ABSTRACT An apparatus for automatically removing fins of castings wherein respective air springs are provided to resist a component in the normal direction and a com ponent in the tangential direction with respect to the hone grinding surface of the contact surface of a hone and work of the grinding resistance applied to the grindinghone and are made to be fed with air pressures set in response to the size, thickness and the material of the tin of the work and a motor to control the work in the direction of the component in the normal direction and a motor to control it in the direction of the component in the tangential direction by converting the displacements of the above mentioned air springs to electric signals with two differential transformers are provided.

9 Claims, 12 Drawing Figures PATENTEU AUB 51975 (L, van

Lil

PATENTED AUB 51975 SHEET PATENTEI] AUG 5 I975 SHEET PATENTEB 75 SHEET PATENTEUAUB 51975 SHEET mgm w APPARATUS FOR AUTOMATICALLY REMOVING FINS OF CASTINGS This invention relates to an apparatus for automatically removing tins of castings.

The common defects of the conventional sequence, pin board, profile control, numerical value control and tracing memory systems are as follows:

I. As there is no compensation for the variation of the dimension of the outside diameter of the grinding hone by its wear, the fin will be left unrcmoved by the wear of the hone.

2. As the variation of the cutting property with the clogging and collapsing of the meshes of the hone can not be coped with, the removed amount of the fin will vary. Particularly, if the grinding is auto mated, self-dressing will be made, therefore the state of the cutting blade of the hone will vary and the ground amount will come to be different.

3. As there is no protective mechanism, when an extraordinary force is applied to the hone, there will be a danger.

In the template in the profiling system, the memory tape in the tracing system and the instruction tape in the numerical value control, unless the fin removing operation starts at the start setting point for the work and the working is made at the same speed, the work and tape will deviate from each other, a large grinding resistance will be applied to the hone and the hone and work will be likely to break.

4. The grinding speed can not be adjusted in response to the material, size and thickness of the fin. The desire to make the grinding speed high in the part having no tin and to make it low in the part where the fin is hard and thick can not be satisfied.

5. The grinding part is constantly repeatedly moved in the position but does not stop in a fixed position due to the inertia. The stopping position is related with the characteristics of the motor, the weight of the grinding part and the precision and friction of the sliding part of the apparatus and there is no function of absorbing the inertia for the variation of the cutting speed. Therefore, an impact force will be likely to be applied to the work and hone.

An object of the present invention is to provide an apparatus for automatically removing fins of castings wherein the above mentioned defects of the conventional fin grinding are eliminated.

FIG. 1 is an explanatory view of the state of contact of a hone and work with each other.

FIG. 2 is an elevation of an embodiment of the present invention.

FIG. 3 is a plan view of FIG. 2.

FIG. 4 is a partly sectioned elevation of a hone shaft unit.

FlGv 5 is an explanatory view of the controlling relation of the hone and work.

FIGS. 6u-d are explanatory views of the positions of the hone. work and the core of a differential transformer C.

H65. 711 and h are views showing the relation of the positions of differential transformer and core.

FIG. 8 is a block diagram showing the controlling relations of the differential transformers C and D and mo tors M, and M In the present invention, a grinding hone is supported with air springs so that the tip of the grinding hone in contact with a work may act as a feeler for detecting fins with a component Fn in the normal direction and a component Ft in the tangential direction with respect to the hone grinding surface as shown in FIG. 1 and the displacements of the air springs produced by the fluctuation of the grinding resistance may be converted to electric signals by differential transformers to control the displacements of the work or hone and to automatically remove fins of castings.

ln FIGS. 2 and 3, l is a rotary hone set on a supporting stand 16, M is a motor for driving the hone through a belt and set on a supporting stand 2.

W is a work. 3 is a fin to be ground. 4 and 5 are sup porting stands. The work on the supporting stand 4 is rotated by a motor M set on the stand 5.

7 is a base of the present apparatus. A supporting stand 6 is moved through a screw rod 8 in the direction of the X axis by a motor M provided on the base 7.

A motor M is provided on the supporting stand 6. The supporting stand 5 is moved by a screw rod 9 in the direction of the Y axis.

A supporting stand 30 is provided through a rotary shaft 42 on a supporting stand 10 on the base 7. A supporting pillar ll is provided on the supporting stand 30. A supporting plate 13 is made movable up and down by a motor M through a screw rod 12 in the direction of the Z axis.

[4 is a nut fitted to the above mentioned screw rod 12 and fixed on one end surface to the above mentioned supporting plate 13.

The supporting stand 2 is at right angles to the supporting plate 13. The supporting

stand

2 and 16 are connected with each other by means of a pin 17 through a supporting frame 15 of the supporting stand 2.

Air springs (bellows) A and A and a differential transformer C are provided between the above mentioned supporting

stands

2 and 16.

The air spring A is fed with an air pressure Pn preset by the later described method but will be displaced by the force in the direction of the component Fn of the hone and the displacement will be detected by the differential transformer C.

The air spring A is also fed with an air pressure P'n (Pn 3 P'n) to stabilize the displacement of the supporting stand 2.

A hone shaft unit shall be explained in the following with reference to FIG. 4.

Its main component parts are a hone to grind fins of works, its rotary shaft 32, a pulley 31 provided at one end of the rotary shaft 32 to hang belts, a differential transformer D to detect anaxial displacement of the hone by the component Fl applied in the axial direction of the hone, air springs B and B to resist the component Ft,

pressure receiving plates

18 and 19, bearings 20 and 21,

stroke bearings

22 and 23 and a hone shaft barrel 24.

The hone rotary shaft 32 is rotatably supported in both shoulder parts with bearings 20 and 21 which are also supported respectively with the

pressure receiving plates

18 and 19 which can slide within the hone barrel 24 so that the hone shaft 32 may be displaced in the axial direction while rotating.

The air springs B and B are provided respectively between the

pressure reeeiving plates

18 and 19 and the 3 end walls 33 and 34 of the hone shaft barrel 24. The internal pressure Pt and P't of the air springs are fed from a compressed air source respectively through pressure reducing valves. passages 25 and 26 in the walls 33 and 34 and annular paths 3S and 36.

The above mentioned internal pressures Pt and P! are set by the later described method.

In order to detect the displacement of the air spring B. that is the displacement of the hone shaft 32 with re spect to the hone shaft barrel 24, an L-shaped lever 27 is provided to project out of one end of the outer peripheral side of the pressure receiving plate I8 and to come out of the hone shaft barrel 24 through a cut groove 28 of the hone shaft barrel 24.

The end part of the lever 27 is in contact with the tip of a shaft 39 of a core 37 of the differential transformer D fixed to the outside of the hone shaft barrel 24 through a pressing force of a spring 38.

By the way. the above mentioned air spring 8 is to stabilize the displacement of the hone shaft.

The operation of the grinding hone to remove fins of castings in the present invention shall be explained in the following.

First of all. the setting of air pressures of the air springs A, A. B and B shall be explained.

In setting air pressure of the air spring A, the fin of the casting is made to approach the hone without rotating the casting (the movement of the work in the direction of the X axis by the motor M is controlled), a part of the fin is experimentally ground while producing a component Fn and. just when the grinding ends (in the state of (C) in FIG. 6), the required air pressure Pn of the air spring may be determined.

For this, if the handle ofa cock of the pressure rcducing valve is properly rotated, the required pressure Pn will be able to be determined.

At this time, the following formula will hold. (Sec FIG. 5.)

FM X L =1 X Pn The position of the core of the differential transformer C at this time is so set as to be in the neutral position. (Sec (C) in FIG. 6.) This air pressure Pn is a force pressing the work against the hone required to grind the maximum width part of the bottom part of the fin.

Next. in setting the air pressure Pt of the air spring B. in the state of (C) in FIG. 6 of the above mentioned experimental grinding, the work W is rotated to produce a force Ft.

The Ft at this time will be of the maximum value as of Ft. Therefore, the air pressure P! which can resist it may be set by rotating the cock of the pressure reducing valve.

If the air pressure Pn and Pt of the air springs A and B are thus set. the pressures P'n and P! of the air springs A and B may be so set as to be Pn Z P'n and Pt 5. P! by rotating another cock of the pressure reducing valve.

The relation between the relative positions of the work W and hone I in the direction of the X axis and the differential transformer C shall be explained in the following. [Sec FIGS. 3, 5, 6 and 7 (41).]

First of all. it is so designed that. when the work W and hone l are not in contact with each other as shown in (a) in FIG. 6. Fri =0 and a core 41 of the differential transformer C may be displaced upward by the force of a spring 40 as illustrated.

The voltage generated by the differential transformer C in this case will be positive. In FIG. 7, 10 shows the position of the core and its generated voltage is shown by V0.

When the tin 3 of the work begins to contact the hone I, a component Fn will be generated and the core 41 will be pushed more or less to be in the state of (b) in FIG. 6. I

In this state. the fin is ground by the operation of the circuit of the later described apparatus of the present invention.

In (a) in FIG. 7, ll toll show the positions of the core 4] and the voltages generated by the differential transformer C are V to V When the grinding of the fin ends. the state of (C) in FIG. 6 will be made. The position of the core 41 at this time will be substantially in the neutral position of the differential transformer C and its generated voltages will be V to V When the grinding is further continued, the component Fn will quickly become so large that the core 4] will move in the direction reverse to the above mentioned neutral position and the generated voltage will be less than minus V. (d) in FIG. 6 shows this state.

Further. in FIG. 7, while the position of the core 4] is I to l by the later described Schmidt circuit. its out put voltage will be zero and a nonsensitive zone will be formed.

The above explanation is summarized as in the following table with reference to FIG. 6.

By the way. in this table, the differential transformer is C and the motor M rotates with the output of the later described Schmidt circuit to control the linear movement in the direction of the X axis of the work.

Table for explaining FIG. (1

The control of the rotation of the work by the motor M is made in the relation of the component F air spring B and differential transformer D.

In this case, as different from the case of the above described control of the linear movement of the work, when Ft is 0 or of a small value close to O, that is, in the state of (a), (h) or (c) in FIG. 6, the core of the differential transformer D will be in the neutral position and the motor M, will not rotate. At the end of the state of (C), by its signal, the motor M will rotate at a low speed. When F! is of a corresponding value by the contact with the fin, the grinding will be continued.

The operation of the present apparatus shall be explained in the following with reference to FIG. 8. First of all, the main steps of the automatic grinding of fins with the present apparatus shall be enumerated.

First step: The motor M to feed the work with respect to the hone normally rotates at a high speed.

Second step: The grinding of the fin in the part in contact with the hone while Fn is being produced begins but the work does not rotate.

Third step: The grinding of the fin in the above mentioned contact part ends. (The state of (C) in FIG. 6.)

Fourth step: The rotation of the work begins.

Fifth step: When a new fin is contacted by the rotation of the work, as F! is larger than the corresponding value, the grinding of the fin will be continued.

Sixth step: When the hone enters the dead angle of the work, F! will become infinite. In this case. the motor M will reversely rotate at a low speed and the motor M will stop.

Seventh step: The grinding of the fin ends and the motor M reversely rotates at a low speed to return to the original fixed position.

The above steps shall be explained with reference to the block diagram in FIG. 8.

In the first step, as the differential transformer C is in the state of (a) in FIG. 6, the electromotivc voltage of the differential transformer C will be an input in the Schmidt circuit S. and, by its output, the motor M, will be normally rotated at a high speed through a relay R to make the work of the first step.

In the second step, as the differential transformer C is in the state of (b) in FIG. 6, due to the value of the electromotive voltage of the differential transformer C, by the Schmidt circuit 5,, the relay R will be switched over to a current source for low speeds and the motor M will normally rotate at a low speed and the fin grinding in the third step will be also made.

In and after the fourth step, any of the following five steps is made.

4 I: In the case there is no fin:

By the input electric power V of the Schmidt circuit, the current source of the motor M will be cut by the relay R through the Schmidt circuit and at the same time the relay R will be operated to switch on the current source of the motor M that is to say, the work will begin to rotate.

At this time, as there is no fin, the differential transformer I) will be in the state of V... [See (h) in FIG. 7| the Schmidt circuit will be in the state of S and the relay R will be normally rotating the motor M at a high speed.

4 2: In case a fin is present:

The motor M will remain stopped, the electromotive force from the differential transformer D will become V, and, by the relay R the motor M, will be switched over to the normal rotation at a low speed to grind the fin.

4 3: In case the hone enters the dead angle of the work:

The electromotive force of the differential transformer D will be in the state of V the Schmidt circuit S will operate the relay R the motor M, will be reversly rotated and the motor M, will be stopped.

4 4: In case the hone bites into the work:

The electromotive force of the differential transformer C will be in the state of V the relay R will be operated by the Schmidt circuit S the motor M will reversely rotate and the work will retreat.

4 5: In case the work makes one rotation:

When the work makes one rotation, the current source of the motor M, will be cut by the relay R the rotation of the work will stop and the motor M will reversely rotate to return the work to the original position.

By the way, when the work is a rectangle long in the direction of the Y axis, the displacement of the work may be controlled with the motor M. The control of the motor M is exactly the same as the control of the rotation of the motor M and the current source may be switched over so as to control the motor M instead of the motor M Further, in FIG. 2, a rotary shaft 42 is provided between the supporting stands 10 and 30 so as to be used on manually setting the position of the hone with respect to the work.

The present invention is of such formation as is described above, therefore has an effect of eliminating various defects of the conventional grinding of fins and is summarized as follows:

I. It has a mechanism wherein, when the fin contacts the tip of the hone, the bone will escape in response to the thickness, size and hardness of the fin.

Further, when the hone removes the fin and reaches the body of the work, the advance of the work will stop. When the work receives a force from the hone, the work will retreat. That is to say, as the tip of the hone acts as a feeler of a fin detector, even if the outside diameter of the hone varies, the tip of the bone will be always in contact with the root of the fin.

2. The matrix of the profiling system, program of the numerical value control and magnetic tape tracing memory are not required.

3. Irrespective of the chucking posture, the starting point of the working can be freely selected anywhere.

4. The inertia force of the grinding head caused by the high speed of the working can be adjusted by adjusting the pressure of the air spring.

As in the above, in the present invention, the operation of removing fins of castings can be reasonably and simply automated.

We claim:

I. An apparatus for automatically removing fins of castings characterized by comprising a first air spring means for resisting a component in the normal direction with respect to the hone grinding surface of the contact surface of a hone and work of the grinding resistance applied to the grinding hone, a second air spring means for resisting a component in the tangential direction, a means of feeding said two air spring means with desired air pressure set in response to the fin of the work, a first differential transformer for converting the displacement of said first air spring means to an electric signal, a second differential transformer for converting the displacement of said second air spring to an electric signal, a first motor means for controlling said work in the direction of said component in the normal direction and a second motor means for controlling said work in the direction of said component in the tangential direction.

2. An apparatus for automatically removing fins of castings according to claim 1 characterized in that said first air spring means is provided between two parallel supporting stands which are connected with each other by means ofa pin through a supporting frame of one of the supporting stands.

3. An apparatus for automatically removing fins of castings according to claim 1 characterized in that a hone shaft unit includes said second air spring means and second differential transformer.

4. An apparatus for automatically removing fins of castings according to claim 3 characterized in that said hone shaft unit further includes a hone rotary shaft, a pulley provided at one end of said rotary shaft to hang belts, a pair of pressure receiving plates, a pair of bearings, a pair of stroke bearings provided on the outer periphery of said shaft and a hone shaft barrel containing these members.

5. An apparatus for automatically removing fins of castings according to claim 2 characterized in that the air pressure of said first air spring means is set by the formula wherein Fn is a component in the normal direction with respect to the hone grinding surface of the contact surface of the hone and work Pn is a component in the tangential direction, 1 is a distance between the pin and air spring means and L is a distance between the pin and the contact point of the fin and hone.

6. An apparatus for automatically removing fins of castings according to claim 2 characterized in that the air pressure of said second air spring means is set by rotating a pressure reducing valve so as to feed an air pressure corresponding to said component in the tangential direction just when the grinding ends.

7. An apparatus for automatically removing fins of castings according to claim 1 characterized in that said first differential transformer consists of a core and spring. the core is deviated upward by the spring and the generated voltage in this state is positive.

8. An apparatus for automatically removing fins of castings according to calim 1 characterized in that said means of feeding the first air spring means with an air pressure comprises a compressed air source, a pressure reducing valve and paths.

9. An apparatus for automatically removing fins of castings according to claim l characterized in that said means of feeding the second air spring means with an air pressure comprises a compressed air source. a pressure reducing valve, paths in both end walls of the shaft barrel and annular paths.

Claims

1. An apparatus for automatically removing fins of castings characterized by comprising a first air spring means for resisting a component in the normal direction with respect to the hone grinding surface of the contact surface of a hone and work of the grinding resistance applied to the grinding hone, a second air spring means for resisting a component in the tangential direction, a means of feeding said two air spring means with desired air pressure set in response to the fin of the work, a first differential transformer for converting the displacement of said first air spring means to an electric signal, a second differential transformer for converting the displacement of said second air spring to an electric signal, a first motor means for controlling said work in the direction of said component in the normal direction and a second motor means for controlling said work in the direction of said component in the tangential direction.

2. An apparatus for automatically removing fins of castings according to claim 1 characterized in that said first air spring means is provided between two parallel supporting stands which are connected with each other by means of a pin through a supporting frame of one of the supporting stands.

5. An apparatus for automatically removing fins of castings according to claim 2 characterized in that the air pressure of said first air spring means is set by the formula Fn X L l X Pn wherein Fn is a component in the normal direction with respect to the hone grinding surface of the contact surface of the hone and work, Pn is a component in the tangential direction, l is a distance between the pin and air spring means and L is a distance between the pin and the contact point of the fin and hone.

7. An apparatus for automatically removing fins of castings according to claim 1 characterized in that said first differential transformer consists of a core and spring, the core is deviated upward by the spring and the generated voltage in this state is positive.

9. An apparatus for automatically removing fins of castings according to claim 1 characterized in that said means Of feeding the second air spring means with an air pressure comprises a compressed air source, a pressure reducing valve, paths in both end walls of the shaft barrel and annular paths.