US3402776A

US3402776A - Device for impact loading a solid body

Info

Publication number: US3402776A
Application number: US455090A
Authority: US
Inventors: Alexandrov Evgen Vsevolodovich
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-05-12
Filing date: 1965-05-12
Publication date: 1968-09-24
Anticipated expiration: 1985-09-24

Description

P 1963 E. v. ALEXANDROV ET A1. 3,402,776

DEVICE FOR IMPACT LOADING A SOLID BODY Filed May 12, 1965 PR/OR ART States Patent 3,402,776 DEVICE FOR IMPACT LOADING A SOLID BODY Evgeny Vsevolodovich Alexandrov, 4 Poselok Vugi, kv. 9, Lyubertsy, Moscow, U.S.S.R. Filed May 12, 1965, Ser. No. 455,090 11 Claims. (Cl. 173133) ABSTRACT OF THE DISCLOSURE A device for impact loading a solid body having two colliding systems, a first of which directly acts on the body and is composed of one or more working members, the other system being a striker constituted of a material having a smaller elastic modulus than the material of the working member which contacts the solid body, there being a clearance provided between the solid body and the working member which strikes it or between the working members of the first system.

The present invention relates to devices for impact loading a solid body.

More particularly, the present invention relates to impact devices, comprising at least two colliding members, one of which is a striker while the other is a working member which receives the blows from the striker and directly acts on the solid body.

Widely known in the art are impact devices, as well as machines and appliances using such devices.

At present, the principal parts of such known impact type devices are usually manufactured of steels of special grades, preferably alloys, which limits their speed of operation on account of the great specific weight of the ma terial being used (about 7.8 to 7.85 .g./cm. Moreover, this causes the Weight of such devices and machines to be relatively great, which limits their capacity and efficiency, Besides, the use of special grades of steels in impact type devices increases their cost price.

From the practice of drilling operations effected with the use of impact type devices it is known, that an intermediate member receiving impact forces from a striker and transmitting them to the working member has a relatively short service life. Such an intermediate member in impact type drilling machines is, as a rule, also manufactured from special grades of steels.

The above-said disadvantages are to a certain degree inherent to any known impact type devices.

An object of the present invention is to eliminate said disadvantages.

Another object of the present invention is to provide an impact type device, in which the colliding members, with the exception of the working member, directly acting on the solid body, are manufactured from cheaper and lighter, as well as statically less stable materials, for instance, polymers.

The direct replacement of steel colliding members, with the exception of the working member, by members manufactured from polymeric materials, however, cannot provide a positive effect, since these materials, when interacting with a solid body to be treated, are not capable of producing a stress exceeding the ultimate strength of said solid body.

Indeed, the striker, manufactured, say, of Plexiglas and intended to apply impact blows on the working tool of a riveting hammer, cannot perform useful work on account of its being less stable from the statical point of view than the body to be treated. For example, a rubber ball cannot destroy a brick wall through a direct contact therewith.

As to their impact values, however, the great majority 3,402,776 Patented Sept. 24, 1968 "ice of polymeric materials considerably exceed the best grades of alloy steels. Given in the table below are the comparative characteristics of steels and some polymeric materials in conventional units.

TABLE Permis- Specific Material Density Elastic sible com- Critical storing modulus pressive speed energy stress 1 1 1 1 1 Plexiglas 0. 15 0.039 0. 22 2. 8 1.2 Commercial organic glass.--" 0. 15 0. 018 0.25 4. 7 3. 4 0.17 0.026 0.78 3. 7 8. l 0.17 0. 042 O. 38 4. 4 3. 3 0. l6 0. 017 l7 3. 5 2 0.16 79.10- 0 0125 ll 20 Hence, a still further object of the present invention is to use the advantages of polymeric materials for performing useful work, and to exclude the disadvantages caused by their relatively small elastic modulus and permissible stresses.

According to the present invention, in the device for applying an impact load on a solid body, said device comprising at least two colliding members, one of which is a working member directly affecting the solid body, there is provided a clearance between the colliding members themselves or between the assembly of colliding members and the solid body before each collision of said members. At least one of the colliding members in the device, with the exception of the working member, directly acting on the solid body, is made of a material with a smaller elastic modulus than that of the material of the working member.

In the case where the impact type device has two colliding members, such as a striker and a working member, it is expedient to manufacture the striker from a material having a smaller elastic modulus than that of the material of the working member. In such a case, there must be provided a corresponding means to ensure a clearance between the working member and the solid body before each collision thereof.

According to another embodiment of the present invention, the devic comprises three colliding members. One of them is a working member, directly acting on the solid body, while the other is a striker made of a material with a smaller elastic modulus than that of the material of the working member. The third intermediate member is arranged between the two above-said members so as to receive the blows from the striker and transmit them to the working member. In this case, there is also required a corresponding means to provide an additional clearance between the working member and the third intermediate member.

It is also practicable to manufacture the striker and the third member of a material with a smaller elastic modulus than that of the material of the working member, directly acting on the solid body. In such a case, however, there is required an additional clearance between the working member and the solid body before each collision thereof.

If only the third intermediate member of the device is manufactured of a material having a smaller elastic modulus than that of the material of the working member, it is also necessary to provide an additional clearance between the working member and the solid body before each collision thereof.

A first embodiment of a means to provide an additional clearance in the system between the colliding members or between the solid body and the colliding members is essentially a spring disposed inside a pipe. The pipe is connected with a case, and is provided on its internal side with a projection against which the spring thrusts with one end, the other end of said spring thrusting against projections provided on the shank portion of the working member.

Another embodiment of a means for the provision of an additional clearance in the system may be made in the form of a pipe embracing the colliding members, with the exception of the striker, and accommodating a spring. The spring thrusts with one of its ends against the non-operating end of the working member and with its other end thrusting against the end of the other colliding member, i.e., the intermediate one, which is arranged inside said pipe.

The present invention will become more fully apparent from a consideration of the following description thereof, taken in conjunction with the appended drawings, in which:

FIG. 1 is a schematic diagram of a conventional impact type device;

FIGS. 2-5 are diagrammatic illustrations of an impact type device according to the present invention; and

FIGS. 6 and 7 show various embodiments of means intended to provide a clearance in the system.

By way of example, let us consider the schematic diagram and the principle of operation of the impact device, as shown in FIG. 1. A steel striker 1, reciprocating in a cylinder 2, at the end of its working stroke produces a blow on the shank 3 of a steel drilling rod 4 which is a working member. If the mass of the rod 4 considerably exceeds the mass of the striker 1, then, at the moment of impact, a stress wave propagates along rod 4, said wave carrying the energy in the form of potential energy, i.e. elastic deformation, and kinetic energy, i.e., displacement of the rod.

The amplitude of the stress wave, which represents the pressure and force, set up in the rod, depends, first of all, on the speed of the approach of the colliding bodies and on their acoustic rigidity.

In the given case, when the steel striker 1 collides with the steel rod 4 at a speed close to the critical value, the stress and force, generated by the contact of the working head 5 of the rod 4, will be greater than the ultimate strength of the solid body 6 being destroyed. The replacement of the steel striker 1 with a striker manufactured from a polymeric material, whose specific weight is several times less than that of steel, will requir that the following four prerequisite conditions should be met simultaneously.

(1) The critical speed for the substituting material when colliding with an absolutely solid body must exceed the critical speed for steel under similar conditions by as much as /'y /'y times, where:

'y specific weight of steel; 'y specific weight of the substitute material.

(2) The accumulating capacity of the substitute material, i.e. the capacity of storing the energy in the form of an elastic deformation, must not be less than the accumulating capacity of steel.

(3) Relaxation characteristics of the substitute material, i.e. its capacity to regain its initial volumetric state, must not be less than that of steel.

(4) The substituting material must have a capacity to produce stresses close to those, produced by steel colliding with steel.

The properties of polymeric materials enable them to meet the first three conditions, and only the fourth condition remains unsatisfied.

But, if we assume that the drilling rod 4 does not exceed the critical mass and is not in contact with the solid body 6, the energy of the striker 1, which will be preserved on account of its greater critical speed than that of steel, will be substantially transmitted to the rod 4 in the kinetic energy form.

If the rod 4, upon having received the energy, comes into contact with the solid body 6, it will perform the 4- same useful work as if the same quantity of energy were transmitted to it by the steel striker.

Hence, there is a possibility of using a striker of a lighter and statically less stable material than that of the rod 4, and even a material of a smaller specific weight and elastic modulus than the solid body being treated.

FIG. 2 shows a schematic diagram of the described embodiment of the invention.

The striker 21 is composed of a polymeric material and produces a blow on the shank 23 of the steel rod 24, and thereby transmits thereto its energy in the kinetic form. Simultaneously, the rod 24 moves in the direction of the blow, and, encountering the solid body 6 being treated, destroys it in the same manner as in the case described above and represented in FIG. 1.

A particular feature of th embodiment, shown in FIG. 2, as compared with the embodiment, shown in FIG. 1, is the presence of a clearance A 1 between the head 25 of the rod 24 and the solid body, which should be provided before each blow. To this eifect, necessary means are provided in the device as will be discussed hereafter.

The size of the clearance A 1 may be equal to or exceed the distance covered by the end of the shank 23 of the rod 24 during the blow.

The provision of a lighter striker allows to lighten the case accordingly, thus keeping the ratio of masses at the same level as that with the parts manufactured of steel. Yet the capacity of such a device will increase, since the light striker, having the same energy of a single blow, will, under otherwise equal conditions, permit an increase in the blow repetition rate, and consequently, will be capable of a greater efficiency.

In the case described above, there was stipulated a necessary condition to the effect that the mass of the rod, i.e. of the working member, be not greater than the critical one, since, on the contrary, the energy should be transmitted in the form of a stress wave having an inadmissibly low stress incapable of performing, as has been already pointed out above, useful work.

But if, according to the operation conditions, the working member should be of such a length that its mass will inevitably exceed the critical value, this being observed in the majority of cases of practical application, then the device whose schematic diagram is shown in FIG. 2 will prove to be unsuitable. The same is .true for the case where according to the manufacturing process, the working member should Ibe in a constant contact with the solid body being treated such as in riveting, cutting and the like.

In such cases, the most suitable device is that shown in FIG. 3.

The shank portion 33 of the working member 34 is separated, and before each blow there is provided the same clearance A1, but in this case said clearance is between the shank 33 and the remaining portion of the working member 34. The head portion 35 (or point) of the working member 34 may be in a constant contact with the solid body 6 being treated. In this case, the mass of the shank 33 must correspond to the mass of the rod 34, as shown in FIG. 2.

In the case where the Working member 34, for example, the drilling rod, should be of a great length, and consequently of a great weight many times exceeding that of the striker 31, it is both uneconomical and inexpedient to make it of steel.

FIG. 4 shows an embodiment of the device, in which the striker 41 and the rod 44, with the exception of the working point 45, are manufactured of polymeric materials.

The energy, transmitted by the light striker 41 .to the rod 44 of the same material as the striker, propagates in said rod in the form of a stress wave up to the contact with the separated point 45. Its mass is also selected within the range of the critical value, i.e. it is capable of converting the energy of a blow into kinetic energy; and since it is possible, the clearance A1, provided between the point 45 and the solid body 6 being treated, will enable to employ this energy for useful work.

To this effect, the width of the clearance A1 must not be less than the value of the absolute deformation of the rod 44 during the collision or the travel over the distance covered by the end of the shank 43 during its collision with the striker 41.

Let us consider yet another case where the parts of the device are manufactured of steel, said part-s Ibeing first of all the striker 51 and case 52 (FIG. 5). Such an arrangement is most expedient when using already known conventional impact type devices and machines. In such case, it is possible to manufacture the greater portion of the rod 54, with the exception of the point 55, from a light material having a smaller elastic modulus than the material of the point 55. The clearance A1 is arranged in the same manner as shown in FIG. 4.

The kinetic energy of the striker 51 is transmitted to the rod 54, which together with the shank 53 constitutes one member of the system, said energy then propagating in the form of the stress wave.

Then, the energy of this wave is converted again into the kinetic energy, but at the point 55 already separated from the rod 54.

The clearance A1 must be selected so as to ensure the free travel of the point 55 during the entire time of its receiving the energy of the blow from the rod 54.

There may be employed various means to provide an additional clearance A1 before each collision. In the system of colliding members, there is always a clearance between the striker and the additional or intermediate member; on that account of the clearance A1 is essentially an additional one.

As is shown in FIG. 6, a means to provide an additional clearance (between striker 61 and member 64) is formed by a pipe 67, connected with the case 68 of the device, and by a spring 69 accommodated inside the pipe 67 providing the necessary clearance A1.

The pipe 67 on its internal side is provided with a projection against which there thrusts one end of the spring 69, another end of said spring thrusting against projections 11 provided on the shank portion of the working member 64.

The described means is intended to provide the clearance in those devices schematically shown in FIGS. 2, 4 and 5.

Another embodiment of the means to provide an additional clearance in the device shown in FIG. 3 is represented in FIG. 7.

Therein, pipe 12 embraces the colliding

members

73, 74 and 75, with the exception of the striker 71. The pipe 12 accommodates the spring 79 disposed between the ends of

members

74 and 75, to provide the clearance A1.

The means to provide the clearance may be made without the use of springs, for example, with the use of compressed air.

The embodiments for impact loading a solid body according to the present invention allow for considerable decrease in their weight and provide savings in diflicultly available metals.

Besides, the application of the present invention will contribute to a considerable increase of the capacity of impact type machines, as well as to a drastic simplification of the process of manufacturing the principal parts of impact type machines.

What I claim is:

1. A device for applying an impact load periodically on a solid body, said device comprising at least two colliding members, one of which is a working member, directly contacting the solid body; at least one of said colliding members, with the exception of said working member, being constituted of a material having a smaller elastic modulus than that of the material of said working member; and means for providing an additional clearance selectively between the colliding members themselves and the solid body and the colliding members before each collision of said members.

2. A device for applying an impact load periodically on a solid body, said device comprising two colliding members, one of which is a working member, directly contacting the solid body, while the other is a striker, made of a material having a smaller elastic modulus than that of the working member; and means to provide an additional clearance between said working member and said solid body before each collision of said members.

3. A device for applying an impact load periodically on I a solid body, said device comprising three colliding members, one of which is a working member, directly contacting the solid body, while another is a striker, made of a material having a smaller elastic modulus than that of the working member; and the third is an intermediate member, arranged between the other said member for receiving periodic blows from said striker and transmitting them to said working member; and means to provide an additional clearance between said working member and said intermediate member before each collision of said members.

4. A device for applying an impact load periodically on a solid body, said device comprising three colliding members, one of which is a working member, directly contacting the solid body, while another is a striker; and the third is an intermediate member, arranged between the other said members for receiving periodic blows from said striker and transmitting them to said working member and made of a material having a smaller elastic modulus than that of the Working member; and means to provide an additional clearance between said working member and said solid body before each collision of said members.

5. A device for applying an impact load periodically on a solid body, said device comprising three colliding members, one of which is a working member, directly contacting the solid body, while another is a striker, and the third is an intermediate member, arranged between the other said members for receiving periodic blows from said striker and transmitting them to said working member; said striker and said intermediate member being made of a material having a smaller elastic modulus than that of the material of the working member; and means to provide an additional clearance between said working member and said solid body before each collision of said members.

6. A device for applying an impact load periodically on a solid body, said device comprising at least two colliding members, one of which is a Working member, directly contacting the solid body; at least one of said colliding members, with the exception of said working member, being made of a material having a smaller elastic modulus than that of the material of the working member; a guiding pipe for said colliding members, a case, said pipe being connected with said case and including a projection; a spring, accommodated inside said pipe, said spring thrusting with one end against said working membet and with another end against said projection of said pipe to provide an additional clearance selectively between the colliding members themselves and the solid body and the colliding members before each collision of said members.

7. A device for applying an impact load periodically on a solid body, said device comprising two colliding members, one of which is a working member, directly contacting the solid body, while the other is a striker made of a material having a smaller elastic modulus than that of the material of said working member; a guiding pipe for said colliding members, a case, said pipe being connected with the case and including an internal projection; a spring, accommodated inside said pipe, said spring thrusting with one end against said working member and with another end against said projection of said pipe to pro- 7 vide an additional clearance between said working member and said solid body before each collision of said members.

8. A device for applying an impact load periodically on a solid body, said device comprising three colliding members, one of which is a working member, directly contacting the solid body, while another is a striker, and the third is an intermediate member, arranged between the other said members for receiving periodic blows from said striker and transmitting them to said working member, said intermediate member being made of a material having a smaller elastic modulus than that of said working member; a guiding pipe for said colliding members, a case, said pipe being connected with the case and including an internal projection; a spring, accommodated inside said pipe, said spring thrusting with one end against said working member and with another end against said projection of said pipe to provide an additional clearance between said working member and said solid body before each collision of said members.

9. A device for applying an impact load periodically on a solid body, said device comprising three colliding members, one of which is a working member, directly contacting the solid body, while another is a striker, and the third is an intermediate member, arranged between the other said member for receiving periodic blows from said striker and transmitting them to said working member; said striker and said intermediate member being made of a material having a smaller elastic modulus than that of the material of said working member; a guiding pipe for said colliding members, a case, said pipe being connected to the case and including an internal projection; a spring, accommodated inside said pipe, said spring thrusting with one end against said working member and with another end against said projection of said pipe to provide an additional clearance between said working member and said solid body before each collision of said members.

10. A device for applying an impact load periodically on a solid body, said device comprising at least two colliding members, one of which is a working member, directly contacting the solid body; at least one of said colliding members, with the exception of said working member, be. ing made of a material having a smaller elastic modulus than that of the material of said working member; a pipe, embracing said colliding members, with the exception of the member which is the striker; a spring, accommodated inside said pipe and thrusting with one end against the nonoperating end of said wor-king member and with another end against the end of another colliding member, accor'nmodated inside said pipe, said spring providing an additional clearance selectively between the colliding members themselves and the body and the colliding members.

11. A device for applying an impact load periodically on a solid body, said device comprising three colliding members, one of which is a working member, directly contacting the solid body, while another is a striker made of a material having a smaller elastic modulus than the material of said working member, and the third is an intermediate member, arranged between the other said members for receiving periodic blows from said striker and transmitting them to said working member; a pipe, embracing said colliding members, with the exception of said striker; a spring, accommodated inside said pipe and thrusting with one end against the non-operating end of said working member and with another end against the end of said intermediate member, said spring providing an additional clearance between said intermediate and working members before each collision of said members.

References Cited UNITED STATES PATENTS 1,167,975 1/1916 Burlingham l7312'7 2,101,607 12/1937 Boddinghouse 173-133 2,694,383 11/1954 Larcen 173127 2,749,548 6/1956 Turner 173-l33 2,820,433 l/l958 Pyic 173-127 3,186,456 6/1965 Glasgow 14529 3,255,832 6/1966 Leavell 173162 DAVID H. BROWN, Primary Examiner.