US3707739A

US3707739A - Molded brush head

Info

Publication number: US3707739A
Application number: US00096552A
Authority: US
Inventors: B Hermann
Original assignee: NAT BRUSH CO
Current assignee: NAT BRUSH CO
Priority date: 1970-12-09
Filing date: 1970-12-09
Publication date: 1973-01-02
Anticipated expiration: 1990-01-02

Abstract

A brush head of pushbrooms, or the like, with molded threads so that threaded handles can be screwed therein. The threads formed in such brush head have thread deformations that are formed by protuberances located on a pair of mold parts of such configurations so that the contoured portions formed by the mold parts closely approximate a complete thread within the respective openings to receive a threaded end of a broom handle. The contoured portions of the mold parts are fashioned to provide a zero draft or taper angle between the mold parts and the threads formed thereby so that linear parting of the mold parts is then possible. A pair of angularly disposed threaded openings can be formed by the mold.

Description

1 11 3,707,739 Jan. 2, 1973 3,431,967 3/1969 Hip ,ir............................18/45Rx [54] MOLDED BRUSH HEAD Benito J. Hermann, Jr., St. Charles, 111.

[75] Inventor:

Primary Examiner-Leon G. Machlin Attorney-Mueller & Aichele [73] Assignee: National Brush Company, Aurora,

ABSTRACT A brush head of pushbrooms, or the like, with molded [22] Filed: Dec. 9, 1970 threads so that threaded handles can be screwed [21] App]. No.: 96,552

therein. The threads formed in such brush head have thread deformations that are formed by protuberances 521 U.S. c1. ......................15/176, 15/187, 249/176, located on a P of mold parts of slwh configurations so that the contoured portions formed by the mold 425/416 .A46b H00 [58] Field of Search ...306/30; 18/42, 39,134; 15/176,

parts closely approximate a complete thread within [51] Int. Cl.

the respective openings to receive a threaded end of a broom handle. The contoured portions of the mold parts are fashioned to provide a zero draft or taper angle between the mold parts and the threads formed thereby so that linear parting of the mold parts is then possible.

[56] References Cited UNITED STATES PATENTS A pair of angularly disposed threaded openings can be formed by the mold.

15/145 5 Claims, 5 Drawing Figures PATENTEDJM 2 I975 SHEET 1 OF 2 INVENTOR.

BENlTO J. HERMANN JR.

BY wuivz, 6 M

ATTORNEYS.

PATENTEDJAH 2 I973 SHEET 2 OF 2 III I FIG.5

INVENTOR.

BENITO J. HERMANN JR.

BY M m M ATTORNEYS.

BACKGROUND OF THE INVENTION Heretofore, pushbrooms have been formed by a brush head from which extends a multitude of bristles used for sweeping. The brush head, which may be of wood or plastic, would have a threaded opening formed in at least one end or side thereof and conveniently at an angle of about 45 to receive a threaded broom handle. Heretofore, this internal thread was formed by a machining operation which is rather expensive. To provide maximum usability of the brush head, a second threaded opening is provided in the other side of the brush head, also at a 45 angle, into which the same handle can be threaded when the bristles on the broom were bent backward or in a direction to become substantially ineffective. Thus, by alternately changing the broom handle from one threaded opening to the other threaded opening, maximum broom life can be obtained.

In manufacturing pushbrooms of this type, there is a rather extensive and expensive machining operation to form the threaded openings in the brush head. While it is an absolute necessity to machine the threaded openings when the brush heads are made of a solid block of wood, this machining operation becomes an extra and unnecessary step when making the brush head of one of the modern moldable plastic materials. However, heretofore molding a part, such as a brush head for a pushbroom, with an internal thread on two sides of the brush head'required elaborate devices, as for example, the use of disposable sand formed slugs, somewhat like a lost wax process, which would be destroyed after the brush head was molded to leave behind a threaded cavity. That is, the sand slug would be removed, by breaking it apart, from its location within the brush head, thus leaving behind a formed threaded opening or cavity. This is a relatively expensive and impractical procedure whenmanufacturing items of low cost, such as janitor brooms.

SUMMARY OF THE INVENTION An object of this invention is to provide an improved brush head for a pushbroom which is less expensive to manufacture.

Another object of this invention is to provide a molded brush head wherein threaded openings are formed within the brush head during the molding process.

The molded brush head for a push broom of this invention is formed by use ofa mold assembly having two mold parts which move linearly with respect to each other and form a cavity to receive plastic material. The two parts of the mold each have configurated protuberances extending therefrom symmetrically in diametrically opposed relation to one another. A threadlike contour is formed by the configurated protuberances closely to approximate continuous threads formed within the openings, and these threaded openings will readily receive the threaded end ofa broom handle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a pushbroom using a brush head constructed in accordance with this invention;

FIG. 2 is a rear view of the broom of FIG. 1;

FIG. 3 is an enlarged, sectional view taken along broken line 3-3 of FIG. 2;

FIG. 4 is an assembled sectional view of a mold assembly used to form the brush head of FIGS. 1, 2 and 3; and

0 direction from one another along their coextensive axes.

DESCRIPTION OF THE PREFERRED EMBODIMENT Seen in FIG. I is a side elevational view of a pushbroom which is designated generally by reference numeral 10, and which includes a brush bar or head 12 adapted threadily to receive a broom handle 14 in the usual and well-known manner. Bristles 16, of hair or nylon, or the like, extend from the brush head 12 for sweeping surfaces such as floors. Most advantageously, a pair of threaded

openings

18 and 20 are formed on opposite sides of the brush head 12 and, by way of example, may be located at angles of approximately 45 from the vertical axis of the brush head, it being understood that any suitable angle of displacement of these threaded openings may be incorporated. The broom handle 14 has a threaded end 22 formed thereon so as to mate with the threaded

openings

18 and 20 formed in the brush head 12.

When a broom such as this is used for an extensive period of time, the bristles 16 on the brush head 12 tend to bend rearwardly, in the direction of the extended broom handle, and these bristles then become less efficient in their sweeping function. To revive and enhance the sweeping capabilities of the bristles, the broom handle 14 can be removed from the threaded opening 20 and then inserted into the threaded opening 18, which then causes the bent bristles to face forward for good sweeping action, at least until such time as they again bend backward toward the handle. The handle 14 can be unscrewed from the opening 18 and put back into the opening 20 to once again improve the sweeping capabilities of the broom.

Referring now to FIG. 3, the brush head 12 is here illustrated in the cross section and is made of moldable material, such as plastic, or the like, and is fashioned by utilizing the mold assembly illustrated herein. The threads 18a and 20a within the threaded

openings

18 and 20, respectively, have threaded portions thereof removed, i.e. not formed in accordance with their usual configuration, and which is referred to herein as thread interruptions or deformations, which are arranged to provide draft or taper between the two mold parts and the brush head formed thereby. This zero draft or taper angle, or what is sometimes referred to herein as thread interruptions or deformations, allows the mold parts to be linearly separated to remove the molded brush head therefrom. This thread interruption is illustrated in FIG. 3 and is shown by an angle A formed between the substantially vertical portion of the thread 2011 and a position where the thread would otherwise been formed in the usual case so as to engage with the threaded end 22 of the handle 14. The amount of material, i.e. moldable plastic, that is missing from the angle A is the thread interruption or deformation referred to above. This absence of material does not decrease the effective holding capabilities of the threads, but does allow a substantial reduction in the cost of manufacturing the brush head by now allowing the mold parts to be a linearly partable structure. Similarly, angle B, formed at the bottom thread portions of the thread 20a, corresponds to an absence of material like that of angle A, but which absence of material is caused by the other of the two mold parts.

The threaded opening 18 illustrates a non-threaded vertical segment 18b which is a separation area between the two thread-

like contours

18c and 18d and is formed by the mold assembly of this invention, it being understood that the thread. opening 20 has the same configuration. Thus, the thread-

like contours

18c and 18d are each less than one-half the circumference of the opening in which they are formed. However, the thread-like contours or

segments

18c and 18d cooperate to approximate a full thread within the brush head 12. The non-threaded segment 18b, which is between the threaded

segments

18c and 18d, does not affect the holding characteristics of the threaded end 22 within either the threaded

openings

18 or 20, but does allow a thread free area between mold parts whereby the molded parts can be easily separated without interference. v

For a better understanding of the mold parts used to form the brush head 12, reference is now made to FIGS. 4 and wherein a mold assembly 30 is illustrated as being formed of two linearly

partable mold parts

32 and 34. The upper mold part 32 and the lower mold part 34 cooperate along their coextensive axes, indicated by the broken line 42, and form a cavity area 36 corresponding to the contour of the brush head 12 which is formed thereby. The upper mold part 32 has a pair of

configurated protuberances

37 and 38 extending downwardly therefrom and fashioned to form

threadlike contours

18c and 20c, respectively, over a first threadlike contour or segment of the threaded

openings

18 and 20 formed in the brush head 12.

The lower mold part 34 also has a pair of

configurated protuberances

39 and 40 extending upwardly therefrom, and substantially located in the center of the mold part. The

configurated protuberances

37 and 39 in an assembled condition are diametrically opposed one another, along a line approximately 45 from the central axes 42 of the mold 30, and these configurated protuberances cooperate with one another to approximate a full thread within the opening 18 of the brush head 12. Similarly, the

configurated protuberances

38 and 40 cooperate with one another to approximate a full thread within the opening 20, and these threads provide the necessary engaging thread-like contours or segments within their respective openings to become engaged with the threaded end 22 of the handle 14 as shown in FlG. 3.

Referring now, more particularly, to FIG. 5, it is seen that the upper mold part 32 and the lower mold part 34 are clearly linearly partable along their central

coextensive axes

42 and 420, respectively, and that the parting of these mold parts will not interfere with the formation of the threaded

openings

18 and 20 formed thereby. As seen in FIG. 3, the rectangular opening 24 in the bottom of the brush head 12 forms a regress for the central portion of the lower mold part 34 which has the configurated

protuberances

39 and 40. As mentioned above, the opening 24 can be plugged with suitable plastic material after the brush head is removed from the mold. Also, the material which goes into the opening 24 may have bristles fastened thereto so that the bottom of the brush head 12 will be completely covered with bristles. However, it will also be understood that bristles may be located only on opposite sides of the opening 24 and that no additional material need be added into the opening.

What has been described is a simple mold assembly having two linearly separable mold parts for forming brush heads for pushbrooms, and which cuts the cost of manufacturing such brooms. Although it is here illustrated that the mold assembly 30 has means for forming two threaded openings in the brush head 12, it will be understood that the same concept can be used to form but one threaded opening, as well as three or more threaded openings. Furthermore, the concept ofthis invention can be used to form threaded openings in bodies other than brush heads for pushbrooms. Accordingly, variations and modifications of this invention may be effected without departing from the spirit and scope of the novel concepts disclosed and claimed herein.

Iclaim:

l. A head for a workpiece including, a body of molded material having a working portion, at least one threaded opening formed in said body on a side thereof displaced from said working portion, said threaded opening having a plurality of internal threads with thread interruptions therein which allow linear parting of mold pieces during manufacturing of the head, said threads permitting entrance of a threaded handle and providing secure threaded interconnection therewith.

2. The head of claim 1 wherein said body of molded material has a threaded opening on each side of the head and the axis of one opening is at an angle with respect to the axis of the other opening within a range of 40 to 135, and both openings are at an angle with respect to the vertical axis of the head within a range of 20 to 60.

3. The head of claim 1 wherein said body of molded material has a threaded opening on each side of the head and the axis of one opening is at an angle of with respect to the other opening, and both openings are at an angle of 45 with respect to the vertical axis of the head.

4. A brush head for a pushbroom including in combination,

a body of molded material having one substantially flat side and adapted to hold brush bristles,

a plurality of bristles secured to said body and extending from said one side of said body,

a pair of threaded openings formed in said body on the side thereof opposite to said one side, with the axis of each opening being at an angle within the range from 20 to 60 with respect to an axis perpendicular to said one side,

said threaded openings each having a plurality of internal threads with interruptions in said threads on opposite sides of said openings to allow linear parting of mold pieces during molding of the brush head, said threads in each opening being adapted to cooperate with a threaded broom handle to provide secure threaded interconnection therewith.

5. The brush head of claim 4 wherein the axis of one opening is at an angle of substantially 90 with respect to the axis of the other opening, and the axes of both openings are at angles of substantially 45 with respect to the axis perpendicular to said one side. 5

Claims

1. A head for a workpiece including, a body of molded material having a working portion, at least one threaded opening formed in said body on a side thereof displaced from said working portion, said threaded opening having a plurality of internal threads with thread interruptions therein which allow linear parting of mold pieces during manufacturing of the head, said threads permitting entrance of a threaded handle and providing secure threaded interconnection therewith.

2. The head of claim 1 wherein said body of molded material has a threaded opening on each side of the head and the axis of one opening is at an angle with respect to the axis of the other opening within a range of 40* to 135*, and both openings are at an angle with respect to the vertical axis of the head within a range of 20* to 60* .

3. The head of claim 1 wherein said body of molded material has a threaded opening on each side of the head and the axis of one opening is at an angle of 90* with respect to the other opening, and both openings are at an angle of 45* with respect to the vertical axis of the head.

4. A brush head for a pushbroom including in combination, a body of molded material having one substantially flat side and adapted to hold brush bristles, a plurality of bristles secured to said body and extending from said one side of said body, a pair of threaded openings formed in said body on the side thereof opposite to said one side, with the axis of each opening being at an angle within the range from 20* to 60* with respect to an axis perpendicular to said one side, said threaded openings each having a plurality of internal threads with interruptions in said threads on opposite sides of said openings to allow linear parting of mold pieces during molding of the brush head, said threads in each opening being adapted to cooperate with a threaded broom handle to provide secure threaded interconnection therewith.

5. The brush head of claim 4 wherein the axis of one opening is at an angle of substantially 90* with respect to the axis of the other opening, and the axes of both openings are at angles of substantially 45* with respect to the axis perpendicular to said one side.