US2785428A - Cutting continuous strip bristle stock - Google Patents

Description

March 19, 1957 w. c. VAN CLIEF, JR 2,785,423

CUTTING CONTINUOUS STRIP BRISTLE STOCK Filed Jan. 30, 1953 2 Sheets-Sheet l FIGQ1.

INVENTOR.

u 4 mm c. l/A/V (1/5512.

March 19, 1957 w. c. VAN CLIEF, JR 2,785,423

CUTTING CONTINUOUS STRIP BRISTLE STOCK Filed Jan. 30,- 1953 2 Sheets-Sheet 2 FIG. 5

Fla 7 40 FIG. 6

WIMIIMIHIMI I N VENTORA WILL/HM 0. MN CL IE5 JR.

BY i: TTORNEY United States Patent 6 i 2,785,428 CUTTING CONTINUOUS STRIP BRISTLE STOCK William C. Van Clief, In, Baltimore, Md, assignor to Pittsburgh Plate Glass Company, Allegheny County, Pa., a corporation of Pennsylvania Application January 30, 1953, Serial No. 334,274

6 Claims. (Cl. -205) This invention relates to cutting elongated brush strips into sections suitable for forming brushes and it has particular relation to cutting a brush bristle strip comprising an elongated channel having bristles of thermoplastic material secured therein by crimping, whereby to provide sections of a length suitable for forming bristle portions of brushes.

it is one object of this invention to provide a simple and convenient method of securing plastic brush bristles in a channel by selectively partially fusing the butt portions of the bristles in the channel.

A second object is to provide a method of cutting a brush bristle strip by application of which the metal of the channel contiguous to the cut is partially fused and bridged across the cut to lock the bristles from displacement longitudinally of the channel and to provide a squarecut end of pleasing appearance upon the channel.

A third object is to provide a brush bristle section involving a metallic channel which is crimped along its longitudinal edges to retain thermoplastic bristles from vertical displacement and further having the butts of the bristles at the ends fused or sintered into a coherent mass which looks the rest of the bristles from longitudinal displacement.

These and other objects of the invention will be apparent from consideration of the following specification and claims.

The statement of objects has no particular relation to the order of their relative importance. It will be apparent that all of the objects need not necessarily be attained simultaneously.

It has heretofore been proposed to form brush bristle strips by looping double-ended or U-shaped bristles of plastic about a filamentary core disposed in an elongated channel which was crimped along its edges or side walls in order to lock the bristles and the core from outward displacement. The elongated channels were subsequently sheared into sections of a length suitable for forming bristle bodies for brushes of conventional width.

In order to secure the bristles contiguous to the severed ends of the sections from displacement, the corners of the channels were further locally cri-rnped inwardly to close the ends of the channel as well as practicable. However, adequate crimping to prevent loss of bristles was not always attained. In the prior practice it has been customary to cut or sever the sections from the brush bristle stock or bar by an appropriate shearing operation. In such method of cutting, but little or no heat was developed.

The present invention comprises as one feature, the cutting of the channel of a continuous or semi-continuous brush bristle stock or bar by a friction cutting operation in which a considerable amount of heat is generated in a zone conti uous to the cut thus producing sufficient sintering or fusion of the thermoplastic bristles effectively to cohere the butts of the bristles into a more or less homogeneous mass which effectively lock the bristles in the channel from longitudinal displacement. In such cutice ting operation the heat generated is often sufiicient to locally fuse the metal of the channels and the core in some instances to bridge completely across the severed ends or at least producing substantial thickening or clotting of the metal in the zone of the cut thereby to prevent any possibility of longitudinal displacement of the brush bristle sections.

For a better understanding of the invention, reference may now be had to the accompanying drawings in which like numerals refer to like parts throughout and in which:

Figure 1 is a plan view illustrating a simplified or pro totype of cutting apparatus which may be employed in the practice of the invention.

Figure 2 is a side elevational view of the apparatus shown in Figure 1.

Figure 3 is a sectional view of a brush bristle strip which has been severed from the stock or bar by application of the process herein disclosed.

Figure 4 is a side elevational view of a cutting disc or saw suitable for use in the practice of the invention.

Figure 5 is a side elevational view of a cutting apparatus suitable for use in the practice of the invention, which employs a continuous band or ribbon as a frictional cutting device.

Figure 6 is a diagrammatic view showing the use of an electrical coil inductively to heat the ends of a channel in order to fuse or sinter the butts of the bristles in the channel.

Figure 7 is an end elevational view of a piece of stock after it has been cut by means of a friction saw.

In the practice of the invention, stock to be cut into sections is provided as an elongated strip of a length sufficient to be cut into a considerable number of sections. it may even be formed from a spool of metallic tape which is formed to channel section. it is provided with a filling of double-ended bristles doubled about a core and crimped to secure the bristles and core in the channel. The operation may be performed continuously by appropriate machines not constituting a feature of the present invention.

A section of a typical stock is illustrated in Figure 3 as comprising a channel C, having side Walls lit and 11 interconnected by an intermediate or web portion 12. This channel preferably is of iron, mild steel, aluminum or similar metal which is adapted to withstand substantial degree of flexing in the forming process. The bristles, preferably though not exclusively, are of a plastic material of a thermoplastic nature such as cellulose, acetate, cellulose butyrate, nylon or the like, organic materials which can be fused or sintered at a reasonable temperature such as can readily be generated in the cutting operation subsequently to be described. As will be later elaborated upon, thermoset bristles may sometimes be employed. The bristles can be spun by appropriate techniques not constituting a feature in this invention to have double ends permitting the bristles to be doubled about a core element 13 of wire or the like in the channel.

The ends of the bristles are permitted to project so that each unit, in effect, provides two bristles, the interconnecting butt portions of which extend around the core 13. As will be observed in Fig. 3, the side walls of the channel are also inwardly bent in order to constrict the bristles above the core, thus securing them from vertical displacement.

As shown in Figures 1 and 2, the brush bristle stock is in the form of an elongated bar or" definite length, or a continuous strip. In the latter event it is continuously fed forward by suitable power-driven rollers of a forming machine (not shown). It is supported by any convenient means as, for example, a table 14 having a slot 16 for cutting element such as a power-driven saw 17, which may be fixed or transversely movable (by means not shown). This saw is shown in Figure 4. It may be a arssnaa power-driven handsaw of the type used by carpenters. The saw blade is designed to cut by frictional engagement with the channel element. Such saw blades may be formed with teeth 17a, havinglittle orno rake. The saw in;the. formof a disc is supported upon a mandrel 18 driven. by a motor (not shown) or by other appropriate driving apparatus. Preferably, the saw is operated at relatively high speed for example at such speed that the perimeter moves at a linear velocity of 2 or 3. miles per minute, or at such other speed as will produce an adequ-atev amount of heat at the point of contact with the channel. The stock to be cut into sections is pressed against the edge of such revolving disc or saw and the heat .of. frictional contact is sufficient to soften the metal inadvance-of the edge, thus permitting it to be wiped away or spread across the cut as a clot M by frictional contact, rather than by an actual chipping or scraping operation such as occurs when conventional saws embodying cutting-teeth are employed.

The metal at M often will partially or completely bridge across the end at the'cut. At the same time, the heatgenerated is sufficient to cause the butts of the bristles in the channel contiguous to the cut to be sintered or fused into a coherent mass or plug without appreciably charring or burning it. The stock at the conclusion of thecuttingoperation can be advanced manually or by appropriate apparatus (not shown) to a position permitting the next section to be servered.

Insome instances, it may be desired to feed the stock as a continuously formed element to the cutting apparatus, in which case some means should be provided for temporarily stopping the relative longitudinal movement of the stock with respect to the cutting saw at the point of cut. Such means may involve the provision of a carriage for the saw, adapted to move longitudinally in synchronization with the continuously moving stock as it is advanced during the cutting operation and then to move back to its starting position at the conclusion of the cutting operation.

It is also contemplated to draw out a continuously moving strip of brush bristle stock to a considerable length from the forming machine so that one or more sinuations such as is indicated in dotted line in Figure 1 at S may be formed without the exertion of excessive force upon the stock. These sinuations permit the accumulation of the continuously moving stock for a sufficient period of time to permit the cut to be made with a linearly fixed saw.

Subsequently the stock from the accumulations can be quickly advanced to permit the cutting of a next section while a further accumulation for the subsequent section is building up.

It is to be understood that it is by no means necessary to feed the stock forward continuously. In many instances it may be preferred to provide relatively long bars of definite length which can be handled as units andmanually advanced after each cut.

It may sometimes be desirable to heat'the web por tion 12 of the channel along its entire length. By so heating, bristles along the entire channel may be cohered, thus even more strongly securing the bristles in the channel. For this purpose, as shown in Figure i, an appropriateheating device-is provided. Such device in the diagrammaticform of the apparatus shown includes an electrical heating element such as a high frequency inductioncoilZG of copper tubing cooled with'water being connected to a source of high frequency current supplied by bus-bars 21. The field will heat the channel and cause the encased butts of the bristles to cchere along the entire length of the channel. The use of radiant heaters is also included. The ire-heating of the channel mayfacilitate and reduce the effort required in subse quently cutting the channel. Gloves, tongs or other-heat resistant devices may be used in handling the hot channel.

4. The current should be regulated to prevent the channel from becoming so hot as to burn the bristles.

The circular friction saw as disclosed in Figures 1 and of the drawings may be replaced by a friction saw of the continuous ribbon or band type such as is sold by the l3oAll Company, Des Plaines, illinois. These saws are designed to cut by frictional heat, melting the metal in advance of the cutting edge in themanner previouslydescribcd in connection with the circular saw illustrated in Figures 1, 2 and 4. In Figure 5 of the drawings is band iii-W apparatus, in simplified form, embodya frame housing 25' in which is disposed appropriate pulleys (not shown) fora band saw indicated at 25. Since the saw and the saw operating mechanism, per se, do not constitute a part of this invention and are cc -ll products, further detailed illustration thereof is IlO'L neerr d to be necessary. The stock to be cut, indicated at is supported upon the saw table 23 and is advanced agnnst the-cutting edge of the. saw manually or by appropriate apparatus, as may be desired. it is understood that the saw blade is designed to travel at a linear speed of about 2 to 3 miles per minute at which speed, the heat under the edge is sufficient to soften the metal of the stock to such extent that the metal is wiped away in advance of the edge, thus forming thecut. Often it isdepcsited as a bridge across the ,endofthe channel. Simultaneously, the bristle stock contiguous to the metal undergoing cu-ttingis heated up sufficiently to effectlocal sintering of the material. A smooth, toothless disc may also be employed as a friction saw.

If desired, the upper corners of the channels may be slightly crimped as indicated at 30 in Figure 7. Such crimping is not usually required, but should the flow of metal be distorted or insufficient when the cut is made, the crimp will assist in locking the sintered knot or plug in place. It is an advantage of the invention that. the severed ends of the channel are squarely cut.

While friction saws operating largely by heating action are especially useful in the practice of the invention, it is to be recognized that a further embodiment of the invention includes the use of an abrasive disc orband in place of the friction saw. The abrasive cutter does not ordinarily induce flowing of the metal, but rather actually chips or scrapes it way in fine fragments. However, if the grain of the cutter is not too coarse, and if it is operated at proper speed and if the work is advanced under proper pressure enough heat can be generated to sinter the butts of the bristles near the cut into a coherent mass.

A conventional saw having teeth with rake can also be used provided it is operated under conditions to develop.

considerable heat (enough to sinter the bristle stock in the channel at the cut).

This invention also includes firstsevering thesections by conventional cutters with but little orno heat and then generating heat at the ends of severed section by induction or other means and in sufiicient degree to sinter the butts of the bristles at the point of cut, thus locking the bristles in the channel. Means to perform this operation are indicated in Figure 6 and include a coil such as a high frequency induction coil 43 having leads 41. This may be of a diameter sufficient to admit of insertion of the ends of the channel. and the bristles enclosed by said ends without bending the bristles. If a coil of smaller diameter 4 is to be used, a bar 42. may be disposed at'the end of the coil in position to bend back the bristles as indicated at 4-3.- Should the bristles so bent tend to assume a permanent set, owing to their being distorted While hot, they may readily be straightened by bending them back to proper place by hand while they are still hot.

While it is usually preferred to form the bristles of a thermoplastic material, it may sometimes occur that the fusion of the metal at M across the ends of the channel C is sufi'icient to adequately lock the bristles in place through mechanical enclosure. In such instance, the bristles may be of a thermosetting material, or natural bristles of tampico, hair or the like may be employed.

The forms of the invention herein shown and described are to be considered as being by way of illustration. It will be apparent to those skilled in the art that numerous modifications may be made therein without departure from the spirit of the invention or the scope of the appended claims.

Reference is hereby made to copending application to William C. Van Clief, filed of even date under the Serial Number 334,275, now Patent No. 2,737,703, and entitled Bristle Strip Cutting Apparatus. The apparatus disclosed and claimed therein may be employed, if so desired as a further embodiment for performing the cutting operation of this invention.

I claim:

1. A method of cutting brush bristle stock, comprising thermoplastic organic bristles having the butt portions thereof secured in an elongated metallic channel which method comprises contacting the channel with a friction cutting device moving at sufiicient speed to generate heat to sinter the butt portions of the bristles and simultaneously to cut the metal of the channel to form said sections.

2. A method of cutting an elongaed brush bristle stock comprising a metallic channel and bristles of thermoplastic organic material having the butt portions thereof secured in the channel, which method comprises contacting the channel with the edge of a friction saw travelling at sutfici'ent speed frictionally to cut the metal and simultaneously to fuse the bristle stock in the zones of the cut.

3. As an article of manufacture, a brush bristle section comprising a metallic channel, a core disposed in the channel, brush bristles of thermoplastic organic material looped about the core, the portions of the bristles which are looped about the core contiguous to the ends of the section being cohered into a solid mass, the metal at the ends of the channel being fused to form clots bridging across said ends, thus securing the brush bristles from longitudinal displacement from the channel.

4. The method of cutting a brush bristle stock involving a long channel element and brush bristles of thermoplastic organic material secured at the butt portions in the channel, which comprises the steps of pressing the channel at points to be out against a rapidly moving friction saw travelling at such speed as to fuse the metal in contact with the travelling edge of the saw whereby simultaneously to cut the metal and to fuse contiguous portions of the bristles into a coherent mass.

5. A method of locking double-ended brush bristles disposed about a core in a metallic channel from longitudinal displacement from the channel which comprises cutting the channel with a friction saw operated to generate enough heat in the metal at the point of cut to fuse the same and cause it to form a clot of metal across the end of the channel.

6. The method of concurrently securing thermoplastic organic brush bristles in a metallic channel and cutting said channel which comprises pressing the channel against a friction device to cut the same, said device being moved at suflicient speed to generate heat to fuse the portions of the brush bristles disposed in the channel contiguous to the points of cutting.

References Cited in the file of this patent UNITED STATES PATENTS 1,440,616 Mikshel Jan. 2, 1923 1,749,744 Thacher Mar. 4, 1930 2,341,823 Smith Feb. 15, 1944 2,438,156 Dodge Mar. 23, 1948 2,472,003 Cunningham May 31, 1949

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