DISCLOSURE OF INVENTION The present invention encompasses both an apparatus and a method for cutting a workpiece having opposed first and second sides and formed from resilient material to create at least one cut in the workpiece extending between the first and second sides. The apparatus and method of the invention, as disclosed herein, have particular application to the manufacture of bite valves of the type referenced above. Utilizing the teachings of the present invention, one or more openings in the form of slits are formed in the resilient diaphragm of the bite valve while the diaphragm is in stretched condition. When practicing the teachings of the present invention a bite valve is manufactured which operates reliably to effectively seal off fluid flow through the bite valve when opposed bite forces are not applied thereto. The principles of the present invention are applicable to workpieces other than bite valves, for example other types of fluid flow control valves.

A workpiece constructed with the method and apparatus of this invention need not have any specific configuration to work properly. Thus, the workpiece need not be aligned in any particular manner with the cutter blade employed in the method. With this method, the section of the workpiece that is cut will be predisposed to seal. If, however, the current method is employed to cut a workpiece with a special sealing structure, the resilient slit will have enhanced sealing ability over a workpiece that is cut in a non-stretched manner.

The apparatus of the present invention includes first workpiece engagement means for engaging the first side of a workpiece. A second workpiece engagement means is provided for engaging the second side of the workpiece while the first side is engaged by the first workpiece engagement means. The second workpiece engagement means is cooperable with the first workpiece engagement means during relative movement between the first workpiece engagement means and the second workpiece engagement means to stretch the workpiece.

The apparatus also incorporates cutting means movable relative to the workpiece to cut the workpiece and form at least one cut in the workpiece extending between the first and second sides of the workpiece after the workpiece has been stretched by the first workpiece engagement means and the second workpiece engagement means and while the workpiece is in stretched condition.

The first workpiece engagement means and the second workpiece engagement means have opposed clamping surfaces for clampingly engaging the workpiece to maintain the workpiece in stretched condition while the cut is formed in the workpiece by the cutting means.

The invention also encompasses a method of cutting a workpiece having opposed first and second sides and formed from resilient material to create at least one cut in the workpiece extending between the first and second sides.

The method comprises the steps of stretching the workpiece and maintaining the workpiece in stretched condition.

While maintaining the workpiece in stretched condition, the stretched workpiece is cut to form at least one cut in the stretched workpiece extending between the first and second sides of the workpiece.

After the cutting step, the workpiece is allowed to return to an essentially unstretched condition.

The step of maintaining the workpiece in stretched condition comprises applying opposed clamping forces to the workpiece, one of the clamping forces being applied to the first side of the workpiece and the other of the clamping forces being applied to the second side of the workpiece.

Other features, advantages, and objects of the present invention will become apparent with reference to the following description and accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS Fig. 1 is an exploded, perspective view illustrating structural components of a first embodiment of apparatus constructed in accordance with the teachings of the present invention prior to assembly and in conjunction with a bite valve that will have slits formed in the diaphragm thereof by the apparatus; Figs. 2A-2C are cross-sectional views of the apparatus and bite valve illustrating the sequential steps being carried out when forming slits in the bite valve utilizing the apparatus and in accordance with the method of the present invention; Fig. 3 is a view similar to that of Fig. 1 but illustrating an alternate embodiment of the invention apparatus; Fig. 4 is a plan view diagrammatically illustrating the pattern of forces applied to the diaphragm of the bite valve when employing the apparatus of Fig. 1; Fig. 5 is a view similar to Fig. 4, but illustrating diagrammatically the forces applied to the diaphragm of the bite valve when utilizing the embodiment of the apparatus shown in Fig. 3; Figs. 6A-6C are cross-sectional side views of a third embodiment of the apparatus illustrating the sequential stages of operation when cutting a bite valve; Figs. 7A-7C are cross-sectional side views illustrating the embodiment of the apparatus shown in Fig.

1 to cut a different shaped workpiece; and Figs. 8A-8C illustrate sequential steps carried out when utilizing the embodiment of the invention shown in Figs. 6A-6C to cut yet another form of workpiece.

MODE8 FOR CARRYING OUT THE INVENTION Referring now to Figs. 1, 2A-2C and 4, apparatus constructed in accordance with the teachings of the present invention is disclosed which is for the purpose of cutting two parallel slits in a workpiece 10.

Workpiece 10 is in the nature of a bite valve, including a tubular-shaped element 12 having an interior closed by a resilient diaphragm 14. A flange 16 projects outwardly from the tubular-shaped element from a location adjacent to the resilient diaphragm. As illustrated, the flange has an inner surface in the form of a truncated cone converging in the direction of the diaphragm. The bite valve 10 is of integral construction, being formed of rubber or other suitable resilient material.

The apparatus includes a mandrel 20 having a flat distal end 22. The mandrel is inserted into the interior of tubular-shaped element 12 with the distal end 22 engaging the bottom side of diaphragm 14.

The apparatus additionally includes another component which is for the purpose of engaging the top side of the diaphragm 14. More particularly, such component includes a tubular housing 24. Positioned in the interior of the housing 24 is a blade mount 26, the blade mount 26 being selectively releasably attached to the housing within the housing interior by a set screw 28.

Two cutting blades 30 are connected to blade mount 26 and project from the blade mount within the housing interior. The cutting blades are spaced and parallel to one another. Preferably, the cutting blades 30 are releasably attached to the blade mount 26. In the arrangement illustrated, the cutting blades 30 are located in parallel slots defined by the blade mount. A set screw 34 is employed to lock the blades in place, the set screw passing through aligned apertures formed in the blades.

The housing 24 and the blade mount 26 cooperate to define a recess 36 accommodating a resilient pad 38 formed of spongy rubber or the like. Two slits 40 are formed in resilient pad 38 which accommodate and are in alignment with cutting blades 30.

Fig. 2A shows the assembly just described in position over bite valve 10 supported by mandrel 20.

In Fig. 2B the assembly including the housing 24, the blade mount 26, the cutting blades 30, and the resilient pad 38 has been moved downwardly relative to the mandrel and bite valve and is in engagement with the bite valve. When the assembly is in the illustrated position shown in Fig. 2B the rigid end of housing 24 has engaged flange 16 and has deflected the flange downwardly as shown so that the resilient pad 38 is in engagement with the top side or surface of the-diaphragm 14.

Continued downward movement of the assembly will cause the diaphragm 14 to enter recess 36 as shown in Fig.

2C.

Engagement of the flange 16 by the housing 24 and downward deflection thereof as shown in Figs. 2B and 2C will cause the diaphragm to be stretched in radial fashion.

The mandrel 20 and relatively movable housing trap the bite valve therebetween and cause radial outwardly directed forces to be exerted on the diaphragm as illustrated diagrammatically in Fig. 4.

The resilient pad 38 and mandrel distal end 22 apply opposed clamping surfaces to the stretched diaphragm so that the diaphragm is in stretched condition when continued downward movement of blades 30 forms slits in the diaphragm.

These slits, which are designated by reference numeral 46 in Fig. 4, extend completely through the diaphragm from the top side to the bottom side thereof.

After the slits are cut, the upper assembly of the apparatus (as viewed in Figs. 2A-2C) is moved out of engagement with the bite valve. The bite valve is then removed from the mandrel. It has been found that cutting of the slits 46 in this manner provides a secure liquid- type seal at the locations of the slits until the bite valve is bit during use to open the slits.

Fig. 3 illustrates an alternative embodiment of the invention which is identical in all respects to the first embodiment discussed above except for the fact that housing 24A has two indents formed at the bottom thereof and in opposition to one another. Only one of the indents 50 is observable in Fig. 3, it being understood that an indent of like configuration is located in opposition thereto. The disclosed indents are beveled surfaces slanting inwardly toward the bottom end of the housing 24A.

If a housing of the nature of 24A is utilized as previously described with respect to housing 24 to engage bite valve 10, the stretching of the resilient diaphragm 14 will not be uniformly radial as was the case when housing 24, which is round at the workpiece engaging end thereof, is utilized, but rather the resilient diaphragm 14 will be stretched nonuniformly and primarily along a linear stretch axis. That is, the diaphragm will be stretched more at the locations where the housing 24A is rounded than where it is beveled. Fig. 5 depicts diagrammatically with arrows the stretch characteristics resulting from the use of a housing such as housing 24A. In this instance, the linear stretch axis is essentially orthogonal to the direction of slits 46. This would be accomplished by centering the blades 30 with the indents or bevels 50.

Figs. 6A-6C illustrate apparatus which is identical in all respects to the apparatus of the first embodiment described above except that only a single cutting blade 56 is connected to blade mount 26A. This will result in formation of only a single slit in diaphragm 14 after the diaphragm has been stretched and clamped as previously described.

Figs. 7A-7C show the apparatus of the first embodiment, i.e. the embodiment shown in Fig. 1, used to form two slits in a workpiece consisting of a tubular- shaped element 52 and a resilient diaphragm 54. This workpiece too, for example, may be a bite valve; however, it does not employ a flange.

Figs. 7A-7C show the sequential steps being carried out when forming two slits in resilient diaphragm 54. The housing and related structure are positioned over the mandrel 20 and the workpiece as shown in Fig. 7A and then the housing lower end is brought into engagement with the bite valve at the outer circular edge of the bite valve. Continued lowering of the housing and associated structure will stretch the diaphragm as previously described, the diaphragm then being clamped between resilient pad 38 and the mandrel distal end 22. While the diaphragm is in stretched condition, continued movement of the housing relative to the mandrel will cause the blades 30 to form two slits in the resilient diaphragm 54. The housing and structure connected thereto is then raised out of engagement with the bite valve and the diaphragm will return to its unstressed condition.

Figs. 8A-8C illustrate apparatus constructed in accordance with the teachings of the present invention being used to pierce a workpiece 60 which is constructed of rubber or other resilient material and normally has a planar configuration. For example, workpiece 60 may be a flat disc which may be subsequently used as a fluid control valve. The only difference between the illustrated apparatus shown in Figs. 8A-8C and that shown in Figs. 6A- 6C is that the mandrel 20A of the embodiment under discussion is shorter.

Fig. 8B illustrates the lower end of rigid housing 24 in engagement with the workpiece 60. Then as shown in Fig 8C continued downward movement of the housing and associated structure relative to the workpiece and mandrel 20A will serve to stretch the workpiece at the central diaphragm portion thereof positioned on mandrel 20A since the workpiece about the periphery of the central portion is pinched between the housing and mandrel and forced downwardly to some extent. The stretched central diaphragm portion of the workpiece is clamped between the resilient pad and mandrel and the blade 56 forms a slit passing through the central diaphragm portion of the workpiece before the housing and associated structure are withdrawn from the workpiece.