JPH05220844A - Molding machine - Google Patents

Abstract

PURPOSE: To enable lapping a strip of an extensible material like rubber from an extrusion molding machine over a complex configuration by controlling the thickness correctly and thereby to dispense with machining of the outer surface. CONSTITUTION: An insulation casing for an object like a rocket-motor casing is produced by lapping an insulation-material strip 18 over the surface of a rotating mandrel 10. During the lapping process, the said strip 18 conforms most correctly to the geometric configuration of the mandrel 10 through a molding machine with a unique structure to form the configuration of the strip 18. The molding machine automatically varies both taper and width-size of the strip 18. The lapping-processed final product has a smooth surface which requires only minimum finish-processing.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to the manufacture of objects by strip wrapping. In particular, the present invention relates to an apparatus and method for winding strips of insulating material such as rubber on a rotating component or mandrel having rounded or tapered surfaces.

[0002]

Rocket motor casings are conventionally provided with rubber-like inner or outer insulating surfaces. It has been proposed to modify a rubber extrusion machine and a wrapping machine developed for the manufacturing industry of large tires into one suitable for the manufacture of rocket motor insulators. Manufacturing such components by the lapping method is not particularly new. The advantage of this manufacturing method is that the extruder can provide freshly mixed hot and unvulcanized rubber. Rubber is tacky at high temperatures and is easier to process than the same material at room temperature in calender form. The invention disclosed herein is unique in that a modified roll forming machine can be used to shape the extruded rubber strip into the final shape required for the lapping process.

[0003]

The prior art lapping system described above uses two roll formers with an extruder. This roll forming machine
Before wrapping, a finishing touch is applied to the shape of the extruded strip of unvulcanized rubber. The final shape of the strip produced is constant and cannot be changed without stopping both the roll forming machine and the extrusion die and making changes. This existing device
Only cylindrical or conical shaped bodies of constant wall thickness can be lapped. Tapered features must be wrapped in multiple layers using excess material and then finish machined to the desired wall thickness. The usefulness of this basic idea can be increased exponentially if the shape of the strip can be changed during continuous operation of the device. The ability to change the shape of the strips eliminates the need for extremely costly final machining steps, plus the tapered wall thickness that is the surface of revolution for rubber components such as cylinders, domes, cones, etc. Allows parts to be manufactured with small net manufacturing tolerances. Conventionally, the strip is wound on a rotating surface having the surface of a rotating mandrel, so it is of utmost importance to ensure that the strip is properly wound both on the mandrel surface and on adjacent portions of the strip. This presents a particularly serious problem when wound on a curved surface such as a dome, or when the thickness of the insulator has to be tapered.
If the strip is not properly shaped, the strip will not be wound properly and the lay-up that is formed will result in excessive voids due to the nature of the spaces between the strips, resulting in unexpected deformation during the vulcanization stage, Control of wall thickness will be impaired.

[0004]

SUMMARY OF THE INVENTION The present invention uses a novel two roll former that receives rubber strips from an extruder. This molding machine is continuously adjustable during the lapping process and can change the cross-sectional shape (length and taper degree) of the strip to be lapped.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the accompanying drawings, FIG. 1 illustrates a lapping mandrel 10 having an outer surface 12 adjacent the port region which conforms to the shape of a rocket motor casing. A circular hole 14 in the mandrel 10 fits into a rocket motor casing nozzle or an ignition port of the ignition port. The preformed rubber starting ring 16 has a circular hole 14
Surrounding the mandrel 10 adjacent to and carrying a metal ring 17. The outer surface of the mandrel 10 is coated with a suitable release material such as Teflon.

According to the invention, the rubber insulation strip 1
8 starts from a rubber starting ring 16 and is wound onto the outer surface 12 of the rotating mandrel 10. Wrap it properly,
The strip 18 is shown in FIG.
The mandrel outer surface 12 is wrapped at a predetermined constant angle, such as the 45 ° angle shown in FIG. Curved outer surface 1
According to No. 2, it is desirable to wrap the continuous winding portions tightly adjacent one another so that a smooth outer surface is formed and no unwanted voids are created. For this purpose, of course, the cross section of the strip 18 is tapered (so that the outer surface is wider than the inner surface) and the inner edge of the strip 18 forms an angle of about 45 °,
It is necessary to make the outer edges of the same have similar angles. Further, as is apparent from FIG. 1, the thickness of the rubber insulation coating varies from the maximum value adjacent to the rubber initiation ring 16 and decreases with wrapping away from the port region. Need to do so. This also requires that the width dimension of the lapping strip 18 be gradually narrowed during the lapping process.

Means for changing the shape and dimensions of the wrapping strip 18 during the lapping process are illustrated in FIG. The means is a molding machine comprising a fixed roller 20 and an adjustable roller 22. The fixed roller 20 is
It can be driven by any suitable means and is mounted so as to be rotatable about a relatively fixed axis 24. Forming / trim ring 26 is fixed roller 20
Fixedly attached or otherwise attached to the outer surface of the. The inwardly facing surface 28 of the forming / trim ring 26 is provided with an angle that matches the desired angle for the inner edge of the strip 18 to be wrapped. In the illustrated embodiment, this angle is 45 °. The outer radius of the ring 26 terminates in a sharp edge 30.

Adjustable roller 22 with adjustable axis 3
It is mounted close to the fixed roller 20 so that it can rotate about 2. The adjustable axis 32 of the adjustable roller 22 is preferably coplanar with the fixed axis 24 of the fixed roller 20. However, this axis can be adjusted in the plane within an angle θ from an alignment parallel to the axis 24 during the lapping process. This angle θ could be 3 °, for example.

Roller 2 with adjustable slide ring 34
2 mounted on the outer surface. As the name implies, the slide ring 34 is not fixed relative to the outer surface of the adjustable roller 22 and can slide axially and controllably along the outer surface. The slide ring 34
Comprises a slide collar 36 having a sharply extending radially outward edge 38 having an angled inner surface 40. The angle of the inner surface 40 is substantially the same as the angle of the inner surface 28 of the molding / trim ring 26 on the fixed roller 20.

During the lapping process, the slide ring 34 can be positioned using any suitable means. One method shown in FIG. 2 is a rotatable idler push rod having a concentric groove 44 that engages a slidable slide ring 34 and axially positions the ring 34 on the surface of the roller 22. 42 is provided. The movement of the push rod 42 can be programmed by any suitable means, such as, for example, a cam, as shown by the double arrow feathers.

An insulating strip in the form of an unvulcanized compliant material such as rubber is shown in FIG. 3 as strip 18a. The strip has a substantially rectangular cross section. Adjustable roller 22 and stationary roller 20 are positioned adjacent to each other such that molding / trim ring 26 engages the outer surface of adjustable roller 22. Similarly, the sharp edge 38 of the slidable slide ring 34 on the adjustable roller 22 is proximate to, but not in contact with, the outer surface of the stationary roller 20. It is undesirable for either one of the sharp edges 30 or 38 to actually engage the adjacent roller surface. The reason is that such contact may damage the polishing surface of the roller. When the axis 32 tilts within an angle θ, the adjustable roller 22 pivots about a point near its outer surface adjacent but not in contact with the forming / trim ring 26.

The strip 18a is provided in the space between the fixed roller 20 and the adjustable roller 22 and in the area containing the forming / trim ring 26 and the sharp edge 38. As the strip travels through this area, excess burrs 1 along the right edge of the strip, as shown in FIG.
8b is removed by the action of the ring 26. Because the inner surface 28 of the ring is angled, the strip 18 remains with the angled right edge. Similarly, strip 1
Excessive burr 18c along the left edge of 8 has a sharp edge 38
Of the left edge, which is substantially separated by the action of the left edge. If desired, a small cutting wheel can be indexed into the slide ring 34 to complete the cutting of the burr 18c from the strip 18 to be wrapped.

In operation, the adjustable molding machine control can be pre-programmed for the lapping process to be performed. This also includes preselecting the taper change of the strip caused by tilting within the range of the roller axis angle θ, as required by the mandrel surface profile. It will be appreciated that the present invention is not limited to tapering in only one direction. Of course, the adjustable roller axis 32
It is also possible to rotate either up or down parallel to the fixed axis 24 to accommodate complex surface geometries. Similarly, the push rod 42, or other control means, can be programmed as needed and manufactured with varying strip width dimensions to accommodate the needs that arise during the winding process. The end result is that a layup is obtained with a void-free and smooth outer surface 19 as shown in FIG.

The novel forming process of the present invention produces an unvulcanized compliant wrapping strip that is continuously variable in shape and size for wrapping around the surface of a mandrel or other rotating body having a variable curved surface. It will be appreciated that it is possible to do so. Further, it will be apparent that the molding machine can be programmed and adjusted for any desired lapping method. It will also be appreciated that numerous variations may be employed in the present invention without departing from the spirit and scope of the invention. Therefore,
The above description is not to be construed as limiting and should be construed as merely an example. The scope of the invention should be limited only by the appended claims.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a wrapping mandrel wound with an insulating strip, showing a partially enlarged view of a wound state of the insulating wrapping strip.

FIG. 2 is an elevational view of the adjustable molding machine of the present invention.

FIG. 3 is a cross-sectional view of an extruded insulating strip as it enters the molding machine.

4 is a cross-sectional view of the strip of FIG. 3 as it exits the molding machine.

[Explanation of symbols]

10 Mandrel 12 Outer Surface of Mandrel 14 Circular Hole 16 Rubber Starting Ring 17 Metal Ring 18 Strip 18a Strip 18b Burr 18c Burr 19 Smooth Outer Surface 20 Fixed Roller 22 Roller 24 Fixed Axis 26 Ring 28 Inner Surface of Ring 30 Sharp Edge 32 Adjustable Roller axis 34 Slide ring 36 Slide collar 38 Sharp edge 40 Angled inner surface 42 Push rod 44 Groove

Claims (8)

[Claims] 1. A molding machine for receiving a malleable lapping strip and controllably finishing its cross-sectional shape during a lapping process, the machine comprising a first rotating shaft and a substantially cylindrical first molding surface. A first roller, extending radially outward from the first molding surface and
First circumferentially having a surface defining an edge of the strip of
And a second roller having a substantially cylindrical second molding surface spaced apart from the second axis of rotation and the first molding surface and receiving the strip, the second molding surface being A second roller proximate to the first ring and a surface extending radially outward from the second molding surface and defining an edge of a second strip proximate the first ring. A second circumferential ring; means for advancing the lapping strip between the first and second molding surfaces and a surface defining the edges of the first and second strips; and the lapping step. A means for adjusting the angle between the first and second rotation axes, and controllably adjusting the axial position of the second ring on the second molding surface during the lapping step. And a molding machine. 2. The molding machine according to claim 1, wherein at least one of surfaces defining the first and second end edges has a substantially conical shape. 3. The molding machine according to claim 2, wherein each of the surfaces defining the first and second edges has a substantially conical shape. 4. The molding machine according to claim 1, wherein the first and second axes are in a common plane. 5. A method of winding a strip of malleable material on a relatively rotating body, which comprises passing the strip through a molding machine before winding the strip on the body and adjusting the molding machine during a lapping process. And changing the cross-sectional shape of the strip to accommodate changes in the geometry of the body. 6. The method according to claim 5, wherein the change of the cross-sectional shape is performed by taper. 7. A method according to claim 5, characterized in that the change in cross-sectional shape is effected in the width dimension. 8. A method according to claim 5, characterized in that the change in cross-sectional shape takes place both in the width dimension and in the taper.