US2786376A

US2786376A - Rotary impact tool

Info

Publication number: US2786376A
Application number: US404747A
Authority: US
Inventors: Earl G Roggenburk
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-01-18
Filing date: 1954-01-18
Publication date: 1957-03-26
Anticipated expiration: 1974-03-26

Description

March 26, 1957 E. G. ROGGENB URK 2,786,376

I ROTARY IMPACT TOOL Filed Jan. 18 1954 3 Sheets- Sheet 1 Ill F'IG. I

A ORNEY March 1957 E. G. R-OGGENBURK 2,786,376

ROTARY IMPACT TOOL Filed Jan. 18, 1954 3 Sheets-Shpet 2 INVENTOR. EARL G. ROGGENBURK BY 7747i A ORNEY March 26, 1957 E. G. ROGGENBURK 2,786,376

ROTARY IMPACT TOOL F'iied Jan. 18. 1954 s Shets-Sheet s 6O 37 so 3O INVENTOR.

RNEY

ROTARY IMPACT TOOL Earl G. Roggenburk, Cleveland, Ohio Application January 18, 1954, Serial No. 404,747

15 Claims. (Cl. 81-52.3)

lThiS invention pertains to impact tools and, more particularly, to a new and improved mechanism for controlling the impact action of the tool.

It is an object of this invention to provide an impact tool, such as a wrench, screw driver or the like, which has a new, improved and less expensive impacting mechanism.

A further object of the invention is to provide an impact tool which has a minimum of parts, moving and stationary.

A further object of this invention .is to provide an impact tool which has improved impacting action.

Still another object of this invention is to provide an impact tool which can easily be manufactured and assembled.

It is also an object of the invention to provide an impact tool whose impacting parts can quickly, easily and inexpensively be replaced after they have become worn.

A further object of the invention is to provide an impact tool whose impacting parts have a long useful life under severe impact loads.

Still another object of this invention is to provide an impact controlling mechanism with means assuring that the impact occurs at a time when it will result in the maximum torque being applied to the piece being driven.

For a better understanding of the present invention together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings and its scope will be pointed out in the appended claims.

In the drawings:

Fig. 1 is a side view, partially broken away, showing this invention applied to a pneumatic driving motor.

Fig. 2 is a sectional view taken along line 22 of Fig. 1, showing the impacting mechanism.

Fig. 3 is a sectional view taken along line 3-3 of Fig. 2.

Fig. 4 is a sectional view showing a modified form of the invention.

This invention is particularly applicable to impact tools driven by compressed fluid, such as air, and is particularly suitable for impact wrenches, screw drivers and the like.

Because the invention has been perfected for use with an air-driven impact wrench, it will be described in such connection.

As shown in Fig. l a housing 19 encloses an air-driven motor, the details of which are shown, described and claimed in my application Serial Number 309,980, filed September 17, 1952, for a Rotary Fluid Motor. However, it is to be understood that other fluid-driven motors may be used.

The rotary driving motor within the housing 19 drives a splined output shaft 20 which is coupled into a splined socket 21 in a massive hammer means indicated generally by the reference character 22.

The massive hammer means 22 'is mounted within the housing for coaxial rotation with the driving motor, and comprises a first section 25 of relatively large diameter nited State Pawn: or

A 2,786,376 Patented Mar. 26, 1957 and a second section 26 of relatively smaller diameter. The splined socket 21 is located in the hammer section 25 of large diameter, and the section 26 of smaller diameter has a round bore 27 whose axis is in a direction perpendicular to the direction of the axis of rotation of the hammer means and driving motor. Within the bore 27, and forming part of the massive hammer means, is a hammer .pin 28 which can slide in and out with respect to the

massive sections

25 and 26. The mass of the ham mer pin 28 is eccentric with respect to the axis of rotation of the tool so that as the driving motor rotates the massive hammer means centrifugal force tends to throw the hammer pin 28 out of the bore 27. Means are provided within the bore 27 and back of the hammer pin 28 to prevent the hammer pin from moving too far out of the bore 27. The means shown in Figs. 1 and 2 comprise spring means 29, and the means shown in Fig. 4 comprises partial vacuum, as will be explained in more detail. One end of the spring 29 is connected to a cross-pin 30 inserted in a bore 31 extending across the bore 27. The other end of the spring 29 is connected to the pin 32 which is connected across the hammer pin 28. As shown in Fig. 3 the inside end 33 of the hammer pin 28 is cup-shaped providing an annular flange 34 across which the pin 32 is secured and into which one end of the spring 29 extends. A second spring 35 is mounted in the bore 27 between the cross-pin 30 and the end surfaces of the annular flange 34 on the hammer pin 28. The massive hammer means also includes a support shaft 36 integral with the second massive section 26. The hammer pin 28 preferably is round and it has a groove 37 into which the end of a limit pin 38 extends. The limit pin 38 is mounted through the massive section 26 into the bore 27. When the hammer pin 28 is thrown outwardly by centrifugal force the limit pin 38 stops the outward movement of the hammer pin before it goes too far. The hammer pin 28 is provided with a flat face 39 where it forcefully engages an anvil. It also prevents the hammer pin 28 from rotating in the bore 27. Thus the massive hammer means 22 comprises the first and second

massive sections

25, 26, the hammer pin 28 and its associated

pins

31, 32, 38,

springs

29, 35, and the support shaft 36.

The output drive means comprises a drive shaft 45 having a bore 46 within which the support shaft 36 extends with a close running fit whereby the shaft 36 may easily turn with respect to the drive shaft 45. The drive shaft 45 has means at its outer end 47 to connect to devices for running nuts, bolts, screws, etc., and at its other end is provided with an anvil portion 48 which extends over the massive section 26 of the hammer means. Thus the anvil 48 is located in the circumferential path occupied by the portion of the hammer pin 28 which extends outside of the bore 27 when the hammer means is rotating. This causes the hammer pin 28 to strike the anvil 48 a. hard blow which is translated to the output shaft 45 in the form of a torsional force of high instantaneous value.

In order that the impact tool operate at its highest efliciency, it is necessary that the output shaft 45 be tightly coupled to whatever is being driven, for if it is not closely coupled to the nut or bolt an appreciable amount of the impact force is absorbed by the mass of the output shaft 45. In other words, if the force transmission path from the anvil 48 to the nut being tightened is not closely coupled, much of the impact force from the hammer is wasted in accelerating the output shaft 45. This force is then unavailable to do useful work. In order to make sure that the impact tool of this invention operates at maximum efiiciency for every blow the end face 50 of the anvil 48 is inclined at an angle other than degrees with respect to the axis of rotation of the anvil. The hammer means 22 is provided with a bore 51 in the first massive section 25 of the hammer means at a lbcatio'n spaced from the rotary path of the inclined face 50' of the" advil 48. The axis of the sore 51 is preferably parallel to the axis of rotation of the harnmer means. A positioning pin 52 is mounted in the bore 51 with a portion 53 protruding out to a. location where, upon rotation of the hammer means, it will engage the inclined face 50 of the anvil. A spring 54 is mounted in the bore 51 and a screw plug 55 or the like closes the end of the bore. The spring 54 urges the positioning pin 52 forward toward engagement with the inclined face 50 of the anvil. As the hammer means rotates under force from the driving motor the positioning pin engages the inclined face 50 of the anvil 48 thereby rotating the anvil, the output shaft 45 and any nut or bolt holding devices until the force transmission path is closely coupled, then the hammer pin 28 hits the edge 56 of the anvil and delivers a forceful blow to' the nut or bolt.

After the hammer hits its blow, its rotary motion is stopped and there is zero centrifugal force on the hammer pin 28. The spring 29 which was extended as the hammer pin moved part way out of the bore 27 under centrifugal force then pulls the hammer pin back into the bore 27, causing it to clear the underneath surface 57 of the anvil and allowing the motor once again to spin the hammer means 22 at a rate sufficient that the centrifugal force on the hammer pin overcomes the opposite force of the spring 29. When the spring 29 pulls the hammer pin backinto the bore 27 it does so with considerable fo'r'ce'. Therefore it is highly desirable to provide a shock-absorbing compression spring 35 against which the annular flange 34 of the hammer pin hits. This prevents distortion of spring 29.

As shown in Fig. 1, for forward running of the tool the apex 60 of the face 50 of the anvil should be in engagement with the pin 52 at the instant the hammer pin 28 strikes the anvil face 56. For reverse operation the mechanism should be so positioned that it engages the apex 60 at the instant the hammer pin 28 strikes the reverse face 58 of the anvil.

In the embodiment shown in Fig. 4 parts similar to the parts shown in Figs. 1-3 carry the same reference characters. in this embodiment the hammer pin 28 is machined to have a close sliding fit with respect to the bore in the section 26 of the hammer means 22, and an annular O ring 79 is located between the hammer section 26 and the hammer pin 28 in order to provide a substantially air-tight space 71 at the base of the hammer pin 28. A screw plugJ71 is provided in the section 26 at the base of the hammer pin 28.

Under the influence of high centrifugal force the hammer pin 23 extends out of the bore 27 and strikes a blow against the anvil face 56. A partial vacuum is created in the substantially air-tight space 71 when the hammer pin 23 flies out, and this partial vacuum pulls the pin back into the bore 27 after the impact blow has been struck and the hammer has substantially ceased to rotate. The hammer pin 28 will not be pulled back into the bore 2'7 with sufiicient force to cause damage since there is always a slight amount of air in the space 71 which acts as an air cushion as the pin is pulled back into the bore 27.

In the event there should be a slight leak around the O ring 7% and too much air is obtained in the air space 7i,-the operator should remove the air-tight screw plug '72, then position the hammer pin 28 in the proper position'in the bore 27 to provide the correct size air space 71, then tighten the screw plug '72. This quickly and easily re-establishes the correct amount of air in space 71 to permit the hammer pin 23 to fly out under the right amount of centrifugal force, and to provide the proper cushioning action when the hammer pin slams back into the bore 27.

While there have been described what are atpresent considered to heme preferred embodiments of this invention, it will be obvious to those skilled in the art that .4 various changes and modifications may be made therein without departing frbifi the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. In a rotary impact tool having a rotary driving motor; massive rotary hammer means mounted for coaxial rotation with and driven by said rotary motor; said hammer means having a sealed bore whose axis is perpendicular to the axis of rotation of said hammer means, a hammer pin slidably mounted within said here and eccentric with respect to said axis of rotation of said hammer means whereby rotary motion-of said hammer means establishes a centrifugal force which is the sole force moving said hammer pin partially out of said bore, means within said bore exerting a force on said hammer pin opposite to said centrifugal force; and output drive means mounted for coaxial rotation with said hammer means and including an anvil portion located in the circumferential path occupied by the said portion of said hammer pin outside of said bore when rotating, whereby said hammer pin strikes said anvil when centrifugal force causes said hammer pin to project out of said bore.

2. A rotary impact tool as set forth in claim 1, further characterized by tension spring means within said bore connected to said hammer pin to exert a force on said hammer pin in opposition to centrifugal force.

3. In a rotary impact tool having a rotary driving motor; massive rotary hammer means mounted for coaxial rotation with and driven by said rotary motor; said hammer means having a bore whose axis is perpendicular to the axis of rotation of said hammer means, a hammer pin slidably mounted within said bore and eccentric with respect to said axis of rotation of said hammer means whereby rotary motion of said hammer means tends to throw said hammer pin partially out of said bore, retracting means within said bore exerting a force on said hammer pin opposite to said centrifugal force, shock absorbing spring means within said bore for engaging said hammer pin as said hammer pin is retracted within said bore by said retracting means upon sudden reduction in centrifugal force when said hammer pin strikes said anvil.

4. A rotary impact tool as set forth in claim 1, further characterized by said bore and the back end of said hammer pin establishing a substantially air-tight compartment within which a partial vacuum is established as said hammer pin moves due to centrifugal force, said partial vacuum exerting a force on said hammer pin opposite to said centrifugal force for returning said hammer pin within said bore after the hammer pin strikes the anvil.

5. A rotary impact tool as set forth in claim 1, further characterized by said anvil portion having an end face inclined at an angle other than degrees with respect to the axis of rotation of said anvil means, and characterized by said hammer means including a circumferential portion opposite and spaced from the rotary path of said inclined face on the anvil means, a bore whose axis is substantially parallel to the axis of rotation of said hammer means located in said portion of the hammer means spaced opposite said inclined face, a positioning pin slidably mounted in said bore, and means in said bore biasing said positioning pin into engagement with said inclined face.

6. A rotary impact tool as set forth in claim 5, further characterized by the location of said positioning pin in said hammer means being so related to the position of said hammer pin that said positioning pin engages the inclined face of said anvil means and rotates said anvil means to take up all play between the anvil and a tool to which it imparts rotational force prior to said hammer pin striking the said anvil.

7. In a rotary impact tool having a rotary driving motor; massive rotary hammer means mounted for coaxial rotation with and driven by said rotary motor; said hammer means having a sealed bore whose axis is perpendicular to the axis of rotation of said hammer means; a hammer pin slidably mounted within said bore and eccentric with respect to said axis of rotation of said hammer means whereby rotary motion of said hammer means establishes a centrifugal force which is the sole force moving said hammer pin out of said bore, means preventing said hammer pin from being thrown completely out of said bore, means within said bore in en gagement with said hammer pin for establishing a force on said hammer pin opposite to said centrifugal force when the hammer pin is partially out of said bore, and output drive means mounted for coaxial rotation with said hammer means and including an anvil portion located in the circumferential path occupied by the said portion of said hammer pin outside of said bore when rotating, whereby said hammer pin strikes said anvil when centrifugal force causes said hammer pin to project out of said bore.

8. A rotary impact tool as set forth in claim 7, further characterized by tension spring means Within said bore one end of which is connected to said hammer pin and the other end of which is secured to a fixed portion of said hammer means with respect to which said hammer pin moves due to centrifugal force.

9. A rotary impact tool as set forth in claim 8, further characterized by compression spring means Within said bore located between the end of the hammer pin within said bore and the said fixed portion of said hammer means.

10. A rotary impact tool as set forth in claim 9, further characterized by the end of said hammer pin within said bore being cup shaped, a pin connected across the walls of said cup portion, one end of said tension spring being connected to said pin, the lip of said cup portion engaging said compression spring.

11. In a cyclically operating rotary impact tool having a rotary driving motor; massive rotary hammer means mounted for coaxial rotation with and driven by said rotary motor; said hammer means having a bore closed at its bottom end throughout the entire operating cycle and whose axis is perpendicular to the axis of rotation of said hammer means, a hammer pin slidably mounted in sealing engagement within said bore and eccentric with respect to said axis of rotation of said hammer means whereby rotary motion of said hammer means tends to throw said hammer pin out of said bore establishing a partial vacuum in the bottom of said bore which exerts a force on said hammer pin opposite to said centrifugal force; and output drive means mounted for coaxial rotation with said hammer means and including an anvil portion located in the circumferential path occupied by the said portion of said hammer pin outside of said bore when rotating, whereby said hammer pin strikes said anvil when centrifugal force causes said hammer pin to project out of said bore.

12. A rotary impact tool as set forth in claim 11, further characterized by an O-ring around the portion of said impact pin always within said bore for establishing a seal between the wall of the bore and the wall of the impact pin.

13. An impact tool as set forth in claim 11, further characterized by a removable air-tight plug located in the wall of said bore for establishing upon removal a communication between atmosphere and the said bore.

14. In a rotary impact tool having a rotary driving motor; massive rotary hammer means mounted for coaxial rotation with and driven by said rotary motor; said hammer means having a bore Whose axis is perpendicular to the axis of rotation of said hammer means, a hammer pin slidably mounted within said bore and eccentric with respect to said axis of rotation of said hammer means whereby rotary motion of said hammer means throws said hammer pin partially out of said bore, means exerting a force on said hammer pin opposite to said centrifugal force, output drive means mounted for coaxial rotation With said hammer means and including an anvil portion located in the circumferential path occupied by the said portion of said hammer pin outside of said bore when rotating and including an end face portion inclined at an angle other than degrees with respect to the axis of rotation of said anvil means, said hammer means having a portion opposite and spaced from the rotary path of said inclined face on the anvil means, said hammer means having a bore whose axis is substantially parallel to the axis of rotation of said hammer means and located opposite said inclined face, a positioning pin slidably mounted in said bore, and means in said bore biasing said positioning pin into engagement with said inclined face.

15. In a rotary impact tool having a rotary driving motor; massive rotary hammer means mounted for coaxial rotation with and driven by said rotary motor and including a hammer pin, means causing an impact portion of said hammer pin to extend out into an annular impact path during rotation of said hammer means, output drive means mounted for coaxial rotation with said hammer means and including an anvil portion located in said annular impact path occupied by the said impact portion of said hammer pin and including an end face portion inclined at an angle other than 90 degrees with respect to the axis of rotation of said anvil means facing said hammer means, said hammer means having a portion opposite and spaced from the rotary path of said inclined face, said hammer means having a bore whose axis is substantially parallel to the axis of rotation of said hammer means and located opposite said inclined face, a positioning pin slidably mounted in said bore, and means in said bore biasing said positioning pin into engagement with said inclined face.

References Cited in the file of this patent UNITED STATES PATENTS 1,776,057 Weibull Sept. 16, 1930 1,863,378 Meeks June 14, 1932 2,219,883 Amtsberg Oct. 29, 1940 2,326,347 Forss Aug. 10, 1943 2,373,664 Emery Apr. 17, 1945 2,396,498 Fitch Mar. 12, 1946 2,425,793 Fosnot Aug. 19, 1947 2,508,997 Fitch May 23, 1950 2,636,583 Whitledge Apr. 28, 1953 2,684,738 Kaplan July 27, 1954